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Section 5: A nalyzing feature re lationsh ips

C hapter 12Analyzing spatialdata

B u f f e ri n g f e a t u r e sO v e r la y i n g d a t aCalculating attribute values

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314 eetivn 5 : A r^^rly^ziug Jedture rclatinrtships

Most othe problems you solve with GIS involve comparing spatial relationships amongfeatures-in one [ayer or in different layers-and drawing conclusions. Problem solving inGIS is called spatial analysis, and it can include everything from measuring the distantebetween points co modeling thc behavior of ecosystems.The geoprocessing tools in ArcToolbox not only help you prepare data, they also help youanalyze it spatially. In this chapter, you'11 work with two tools that are very' useful in spatialanalysis: buffers and overlays.A buffer is an area drawn at a uniform distante around a feature. Ir representa a critical zone,such as a floodplain, a protected species habitat, or a municipal service area. Features lyingincide the buffer have a different status from features lying outside thc buffer.

A 500-foot bu f fe r a rou nd a s chool def ines an ar ea whereb i l i board ad ver t is ing is p roh ib i ted .

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A nalyz i? , , , , spat ial dais 315

Overlays (union and intersect) identify overlaps between features in two layers, and create adataset in which the lines of overlap define new features. In a union overlay, nonoverlappingarcas are included in the output dataset. A union datases, then, has three types of features:those found only in the first input layer (with (ayer 1 attribute values), those found only inthe second input [ayer (with layer 2 attribute values), and those created by arcas of overlapbetween the two layers (with both layer 1 and layer 2 attribute values).In an intersect overla y, only che overlapping geometry is preserved, and features have attributesfrom both input layers.

Before overlayTwo layers, each withone featur e

After unionA n e w a y e r w i t h

t h r e e f e a t u r e s

Afte r in te rsectA new ayer wi tho n e f e a t u r e

Avocados Avocados

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316 Lectiorr 5: ia /y^z^ z^^ f i ^^z ture re l^r t innchip^

B uffering featuresBuffers are created as polygons in a new layer. Buffers can be drawn at a constant distante(for example, 100 meters) around every feature in a layer, or at a distance that vares accordingto attribute values. For example, buffers representing the range of radio signals from trans-mitters might vary according to an attribute describing the transmirrer strength. Buffers canalso be concentric rings representing multiple distances, such as the arcas within 100, 500,and 1,000 meters of a well.

P . - ^ o _ oC onstant distance

1 7, 1

If features are close together, their buffers may overlap. You can preserve the overlaps orremove them.

Overlaps preserved Multiple rings

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Analyzing spatial data 317

Ex e rc i s e 1 2 aYour goal is to determine the value of harvestable land in lease F so that your lumbercompany can make a bid. In chapter 11, you dissolved forest stands into leases. Thenyou clipped streams and selected goshawk nests within lease F. In this exercise, you'llbuffer the nest and stream layers to show where logging is prohibited. According togovernment regulations, no trees may be cut within 800 meters of a goshawk nest, therange of goshawk fledglings. Nor can trees be cut within 50 meters of a stream. Log-ging near streams leads to erosion of the stream banks, adding sediment to the water.Ihis kills aquatic plant life and disrupts the food chain. ' he prohibition on logging isincreased to 100 meters from streams where salmon spawn.

1 Star t ArcMa p. In the ArcM ap d ialog bo x, c l ick the opt ion to use an e xist ing m ap. In thel is t of ex is t ing maps, d ou b le-c l ick Browse for m aps. ( I f ArcMap is a l ready ru nning, c lickthe File menu and click Open.) Navigate to C: \ESRIPress \G T K A r C G I S \Chapter l2 . C l ickexl2a .mxd and cl ick Open.Fk* 6eodmarksIraerc eixaon iotl' WMbw tle4-u a11+I"J6SL

=. Nes[sf

!- Arennsf'^- ^ leeseF

j :2 1- 13 m ,' R?

et ldA Fa QokO A~dadasFE590938.8] 6[4655: 64 Mct^s

The map shows lease F, goshawk nests, and streams. You'11 begin by buffering thegoshawk nests using the ArcTToolbox Buffer tool.

2 On the Standard toolbar , c l ick Show/Hide ArcToolb ox Window b utton to open Ar cToolbox.

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318 ^cctlo^t 5: AnaIyzzng fc'atrtre relatiansbi/ r

3 In the ArcT oolbox window, click the plu s sign next to Analysis Tools. Click the plus signnext to Pr oximity. nnaysis Toolsfi Extract

Overday4o Proxenky

&tFerM u k i p l e R i n g B u f f e r

L'. Statistics ;^ Cartography Tods

C o n v e r s i o n T o d s. Data Management TOds+ . 9 1 1 1 G e o c o d i n g T o d s+ i> Linear Referencing Tods: Mohile Todo:. Mdtidmension Tods

S a m p l e slo ;^ Schematics TodoFI i4> Server TodsE; 5patial Statistics Todo

Pavones Irrdea Seach Resuks

4 Double-click the Buffer tool.

OK Cancel 1 Er nertr -11how Hek, You'll select the laver with the input features to be buffered, designate an output featureclass, enter a buffer distante, and select a dissolve option.

5 C l ick the Inpu t Features d rop-d own ar row and cl ick NestsF. (Alternat ively, d rag theNestsF layer f rom the ArcMap table of contents and d rop i t in this locat ion.)6 C l ick the Browse b u t ton next to the Outpu t Featu re C lass box. In the Outpu t Featu reC lass d ialog b ox, navigate to \GTKArcGIS \C h a p t e r l 2 \MyData and doub le-c l ickMyTongass.mdb.

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Analyz ing spatial rl,1 / 319

7 In the Name box, type NestBuf. Make sure your dialog box matches the followinggraphic, then click Save.

OutYtR Feature [Isu

LGos P-W Geoddabase Feat e ClassleaseFPersonal GeoddaaseFedeeC.,l o a s e s Fe, ond Ge o d a t a a s e F e a t u re C I a s s

J NeoF Pe, Geoddabese Peone CimSands z_ GmdataauFeature CassJ streye Pmsanal Geodataba e Federe Cass-J strwnn P e r s o n a l G e o d d e e e s e F e a t - c r o s s

The output feature class information is updated.Input FeaturesNestsF

O ea FeM,e essC:"IPresslGTKacGiS^Cnaoterl2yMyDda yroNws. mdbli esie

8 For the bu f fer d istance, make su re the Linear un i t opt ion is selected. In the Linear u ni tbo x, type 800.The neighboring drop-down list shows the type of units, which are meters.Distance [value or field]( Linear unit

1 800 Meters

9 Scrol l down i f necessary, c l ick the Dissolve Typ e dro p-down ar row and cl ick AH.M I T I T 1 1 7 -

i Te otionalEnd T e o tional

Dissolve Type o tional

Dissolve Field s o tionaluOEJECTIDuS h a p eu d

OK

_ u X

11

i_ l

Cancel Envoonments. Show Help

Wherever buffer polygons overlap each other, the overlapping boundaries will be dissolvedto make a single feature.

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320 5ectiorn 5: Arerrlyziug f'itr're reiitionships

10 C l ick OK.C o m o l e r a d

r C lase I has d ia loq w hen c ompb teo suL CeS S I Uy

Start Time : Fr Jun 20 10:46:59 2006Executed (Buffer ) s ssfully.End Tim : Fri Jun 20c 10:96:57 2008(Elapsed Time : 3.00 8820888)

1

The Buffer tool's progress is reported.11 When the operat ion is comp leted, c lick Clase on the window.

The new NestBuf layer is added to the map. Where buffers overlap, the barriers betweenthem have been removed, as you specified.

12 If necessar y, change the color of the b u f fers so they are v is ib le against theLeaseF background.

artwropxO08 0.00.08fsU[t

pxylTdtrc+,p^atysx^ncsC0050Vopby TOds

.. caerzon r0okpata ma,aga,t 0 Tods08000808 r0dsLinear 0.efer n ona iodo. Toba, rodsdOrococ,t r,o,

501200 00 5,000. Snob 5001:. 500)00 510)0)0, Tods

; o g5 el k?

D~LSnrej _Sdection favaees IMSearchReNS 04 Jravma - R u- A- :::: o am1-I 35- uzuA- -N- .i -

Hk Edo v_ .ew 0od,nar lu pse t `0p iac t l an Took W- '*

/3.63 naosz6bnws41

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Analyzing spatial dcrt,r 321

13 In the tab le of contents, r ight-c lick the NestBu f ayer and cl ick Open At t r ibu te Tab le. Athlbllte of NuWul

OR.IFCTID Shape` Shape_Le ngth15J41 894127

R e c o rd HLI 1NShow: P.II 5elected Recoids ( 0 o u t a l 1 S e le c t e d .) Options -The table contains just a single record. Buffers created with the dissolve ALL optionform a single feature called a multipart polygon (a polygon with discontinuous bound-aries). The attributes are the standard four for a geodatabase polygon feature class:OBJECTID, Shape, Shape_Length, and Shape_Area. Because of the dissolve, none ofthe NestF layer attributes are passed on to the output table.Now you'll buffer the Streams (ayer. The buffer sizes for this layer will vary according towhether or not salmon spawn in a stream.

14 Close the Attributes of NestBuf table. In the table of contents, right-click the StreamsFayer and click Open Attribute Table.

OBJECTIO S

3 Poty4ne4 PoN4ne5 PcN4ne

50 No50 No50 Nc50 Nc

Shepe_Area73564075?4 57

4 692363202 8594584105 9877463 929858215 818805104.9993$4181 1845:8.543 863306341 973734

6 Poylyne501Na7 Poly4ne 1001Y..8Pone50No9Poyne50N -__-10PoN4ne--O - No

R e c o r d N_JI >1111 s h o w : All StGed Recdds ( Do u1o1358Seketed)_ 1

"Ihe HasSpawning field shows whether or not a stream has spawning salmon. The Distantefield values of 50 and 100 correspond to the No and Yes values in the HasSpawningfield. (Recall that logging is prohibited within 50 meters of streams, and within 100meters of streams where salmon spawn.)

15 C lose the table. In the table of contents, tu rn of f the NestBu f and Nes tsF layers.1 6 In t h e ArcToolb ox window, dou ble-cl ick the Buffer tool .17 C l ick the Input Featu res d rop-down ar row and c l ick StreamsF.18 C l ick the Browse bu tton next to the Outpu t Featu re C lass box. In the Outpu t Featu re

C lass d ialog b ox, navigate t o \ GT KA r c GI S \ Chapt er l2 \MyData and dou b le-c l ickMyTongass.mdb.

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322 Section 5: Aeialyzingfea r r ( r e r e1atioe5hip(

19 In the Name box, type St r e a mBu f . Make sure your d ia log box m atches the fo l lowinggraphic, then click Save.

[1Gosha,n4Nests P e r s o n a l G e o d a t a b a s e Feature ClassLeaseFPersonae o d a t a b a s e Feature ClassLeases Personal Geodatabase Feature Cass f NestB Personal Geodatabase Feature ClassIJNestsF Personal Geodatabase Feature Cass

25tands Personal Geodatabase Feature CassJ Streams P e r s o n a l G e o d a t a b a s e Feature ClassJ SreamsFPersonaG e o d a t a b a s e Feature Class

20 For the Buffer distante , click the Field option. Click the Field drop- d o w n a r r o w a n dclick Distance.Distance is the field in the StreamsF layer table that contains the values 50 and 100.This time you won't dissolve the stream buffers as you did with thc nest buffers.

21 Make sur e you r d ialog b ox matches the following graphic, then cl ick OK.

Iepo FeahresStreamsF

Output Featixe Class1 C\ESRIPress\GTKArcGIS\Chapter 12`MyData^Tongass. mdb}5tream8utDistante [value or W](- Linear rl

a

iOCance ErwiroraTon ts ... 5hav Help The Buffer tool's progress is reported.

C oap l ef ed C l o s e1r C l os e Ge G e o g o r l e n c a n p M O e d a c c e j yStars Time: Fri Jun 20 11:02:33 2008Executed ( BUtzerj ssfully.End Time: Fri Jun 20c 11: 02:30 2008(Elapsed Time : I.00 seconda)

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Analyzilag spatial d,,n,i 323

22 When the operat ion is completed, c l ick C lose on the window.The new StreamBuf layer is added to the map. At the current scale, however, you can'tget a good look at the stream buffers.

2 3 C l o s e t h e ArcToolbox window. C l ick the Boo kma rks m e nu a nd c l ick S t re a ms C los e up .

Now you can see the difference between the 50-meter buffers and the 100-meter huffers.24 In the tab le of contents, r ight-c lick the St reamB u f ayer and cl ick Open At t r ibu te Tab le.

AUi8i ss d Strear.BdOBJECTID ' Shd,& Dislaice 1 HasS Shape Lenglh S Ares1Poygon50No723165790283033388522Poygon50No32348834183176533773Poygon50N 71962673328128962878

4P 2yjgon 50 No

51241.597013 54 1 . 2 4 1 1 7 6

7Poygon50No 745.677197 29428.3809091Recorr 144l1r HShow. Selec1ed Recoids (0 aut o 358 Sdeded.) O p l ioff lIn addition to its standard attributes, the output table has attributes from the inputtable. (Because you did not dissolve the buffers, the output and input tables have thesame number of records-there is one buffer for each stream. This correspondencemakes it possible to copy attributes from one table to the other.)

25 C lose the tab le. Turn off the StreamsF ayer . Tu rn on the NestBu f ayer . In the tab le ofcontents, only the two bu ffer layers and the LeaseF ayer shou ld be tu rned on.

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324 ' ecton 5: rAealyzing f atore elatianships

2 6 In t h e t a b l e of contents, r ight-click the LeaseF ayer and click Zoom to Layer.

The two buffer layers define the arcas within which trees cannot be cut. In the nextexercise, you'll use overlays to define the arcas in which they can be cut.

27 If you want to sav e you r work, c l ick the Fi le menu and cl ick Save A s. Nav igate to\GTKArcGIS \C h a p t e r l 2\MyData . Rename the f i le my_exl2a .mxd and cl ick Save.28 If you are co nt inuing with the next exercise, leave A rcMap open. Otherwise, exit theappl icat ion. C l ick No i f prom pted to sav e you r changes.

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Analpzing spatial dar, 325

O v e r l a y i n g d a t aA union overlay combines the features in two input layers to create a new dataset. In thefollowing example, one polygon layer represents a land parcel and the other an oil spill. Partof the parcel lies outside the spill and part of the spill les outside the parcel; in the middle,the two layers overlap. When the layers are unioned, the two original polygons becomethree. The crea of overlap becomes a new feature, while the nonoverlapping areas becomemultipart polygons.

Parcel Oil spi l lE- OH spi l l and parceloverlap each otherTwo polygons

Oi l sp i ll and parcelo v e r la p e a c h o t h e r

One polygon One polygon Two polygons

The oi l spi ll and par cel layers are u nioned to create three new p olygons.

What kind of attributes does the union layer have? In addition to its own standard attributes,it includes all the attributes of both input layers. This doesn't mean, however, that everyrecord has a value for each attribute. In this example, Feature 1 in the output table has noSpill_Type value because it is outside the oil spill, while Feature 2 has no Owner or Landusevalues because it is outside the parcel. Only Feature 3, which spatially coincides with bothinput layers, has a value for every attribute.

Input tab lesu Atbibutnof OitSpil

SHAPE' 1 Date Spill_Type

R e c o r d j JF1_t tt ShowAll Selected AUribufes of Parco

SHAPE ' Owner Landuse

1Polygon Ryan ResidenlieI

,_J

R e c o r d: lr J 1J /l Shaw Al 5

Outpu t tab l esAttt Lides of OiSpilLUnion

1 ODiECTin SHAPE F I D P a re e 1 Owner Landuse FID OdSpill Date Spill_1poygon1PyanRe-_ e n h a l2Polgan-13 polygon 1 Ryan Residen[ra1

R e c o r d l J 111HShowAllSele 2 1142000 0,1cled Records [ 1 ou t o f 3 Selected)

The outpu t tab le conta ins the at tr i bu tes of both input layers. Ou tput featu r es get the at tr i bu tes va luesof input featu res w ith which they are spa tially coincident.

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326 ^cctinn 5: Ao/Iyzing je zture rehitionships

A complication arises with the identifier attribute. One of the standard attributes of theunion layer, assuming it is a geodatabase feature class, is the OBJEC'I'ID field, which assignsa unique ID number ro each feature. (With other data formats, the identifier attributeis called FID or OID.) In this case, both of the input layers also have OBJECTID fields.ArcMap doesn't want lo dclete these fields-they may be useful to you-but at the sametime, it doesn't want a table with thrce OBJECTID fields.To resolve the conflict, the OBJECTID fields from the input layers are renamed in cheunion layer. The new name consists of the prefix "FID_" followed by the input layer name.Thus, the parcel layer's identifier attribute is renamed "FID_Parcel" and the oil spill layer's isrenamed "FID_OilSpill."

Attr ibutes o ( OiISpil l t_ onPolygo,! 1 Ryen Resideriid -1 12.00:00

3 POlygan 11Ryen ^Resideriidj2 7 1412000 O2i

anooo al

Renamed OBJEC TID fields

In an intersect overlay, the process is a little simpler, since only the arca of overlap is preserved.An Intersect of che oil spill and parcel layers would consist of a single feature:Oi l sp i ll and p arcel Intersect ion over lay ofoil spill and parcel

One polygonTwo polygons

As with a union layer, an intersect layer includes its own standard attributes plus all theattributes of both input layers. In an intersect, each attribute is populated for every record.A union overlay requires that both input layers be polygon layers. In an intersect, the inputlayers can either be two polygon layers or a polygon layer and a line layer. In the larter case,the output is a line layer.

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Antalyzing spatial dc'.r 327

Ex e rc i s e 1 2 bIn this exercise, you'Il union the nest and stream buffer layers from the previous exerciseto create a single (ayer of che land that cannot be harvested. Then you'11 union thislayer with a layer of stands in lease F. Because new features will be created whereverstand polygons and buffer polygons overlap, every output feature will lic either entirelyinside or entirely outside a buffer. The set of features lying outside buffers representsharvestable land.

1 In ArcMap, open exl2b .mxd from the C: \ESRIPress \GTKArcGIS \C ha pte r l2 folder.

Thc map shows the buffers for streams and goshawk nests. The other layers are turned off.

2 O n t h e S t a n d a r d to o l b a r , c l ick Show/Hide ArcToolbox W indow b ut ton.3 In the Ar cToolbo x window, expand the Analysis Tools i f necessary, then cl ick the plussign next to Ov erlay.4 Double-click the Union tool.

You'll specifv the layers to overlay and designate an ou tput feature class.

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328 tiection 5: Awalyz ing/eaxture relationships

5 C l ick the Input Features drop-d own arrow and cl ick NestBuf.I n p u t F e a t u r e s

F e a t t a e s-NestBuf

1 , 1Output Featu re Clase

_l

1JC ^ E S R l P r e s s ` G T K A r c G I S \ C h a p t e r 1 2 1 D a t a \ Tongass.mdb\NestBuf _Urnon Gol j

OK Cancel j E r v n r o n r n e n t s . . . ShowHelppa>

The selected ayer is added to the list of layers that will be unioned.6 C l ick the Inpu t Featu res d rop-down ar ro w again and c l ick St reamBu f .7 Click the Browse button next to the Output Feature Class box. In the Output FeatureClass dialog box, navigate t o \ G T K A r c G I S \Chapterl2\M y D a t a and double-clickM y T o n g a s s . m d b .8 In the Name box, type NoCutArea . Make sure your d ia log box m atches the fo l lowinggraphic, then click Save.

outatrt Festine ~

Goshosn NestsMLeas.F;i9] Lesas' 1NestButJNestsFstandsJ StreamBuf^tjStreams]StreamsF

Name. NoCutAeaSane es lype. Feature Gasees

r x

Personal Geodatabase Feature CiasePersonal Geodatabase Feature ClassPersonal Geodatabase Feature ClasePersonal Geodatabase Feature ClasePersonal Geodatabase Feature ClasePersonal Geodatabase Feature ClassPersonal Geodatabase Feature ClasePersonal Geodatabase Feature ClassPersonal Geodatabase Feature Class

By default, the output layer attribute table contains its standard attributes plus theattributes from both input layers. Optionally, you can omit the input layer identifierattributes. Alternatively, you can omit all input attributes except the identifiers. Thiscreates a smaller output Cable and is convenient if you don't nccd to work with attri-butes. (If you later decide that you do need the input attributes, you can join or relateback to the input ayer tables using the common identifier attribute.)Right now, all you need are the identifier attributes.

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Analyzinag spatial diu,i 329

9 C l ick the JoinAt tr ibu tes d rop -down ar ro w and cl ick ONLY_FID. (You might have to scrol ldown in the dialog bo x to see it.)

1 0 M a k e s u r e your dialog box matches the following graphic, then click OK.

FaNes. Nesteost-eercB

L. 1JwweFaNaaw_C.{ESFIF.ess1GTKAr[,15'{[hap:e l.1T'YCa[ei,MYtangass.ndb 'NCC utAre%

B0 YSSR t r4 u t e s I o nCNIY FIDk Y Ta lvanc e o t ime Mefes -r Gaps Abwed^500sr$

Cercel^ Errvkemnnts... Sh o w H e l p ?a

11 When the operat ion is completed, c lose the progress window.FA. Era V- @,0100.05 1 ert Seh ban Iooa p(nmw 9010

'.176274

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S a mp b sSde00KS Tm1,+. Server T..5

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.._$00041 15 5.a968E.Y]Mtars _- _- - - - - - - - ---------The NoCutArea layer is added to the map. The new layer , consisting of all bufferedarcas from the two input layers, defines the zone where no trees may be harvested.

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330 5crtion 5: Analyzing f'atnrc Iationl7i^s

12 In the table of contents, right-click the NoCutArea ayer and click Open Attribute Table.o e . H C T I O S n . a n o _ s 4 ,-letr 1 xe.1e 1 1 st~J4.tgm1 1 , 4 1 .

Polyg8o -2 Paygon_-.

101 1

-1I

9 9 9 1 1 5 90 8432 ng4224

14189 9145984705804606

3 Paygpn 12 -I 72. 384012 288379 5520264 Pdygon 13 -, 836 042854 33950 4578085Potygon 141 -1 355 953218 9943 3914056 P.~ 15 -1 710 344284 34399 9931116 P0Fyg0n 19 1 -1 L 527 779116 15245 2222616 PMgon 20 -1 --- 749351306 167603317619'Pdy9m 21 I

-11340 782361 59211 602459

10 Pdyg00 221 -1 106 241728 291 609820R e c a e 14 JJ,1Shaw I S e i= _ d e d R e c a d o 1 0 ou t o [-2 t6 Seba ted ) p p o n s

The table contains the four standard polygon feature class attributes (OBJECTID,Shape, Shape_Length, and Shape_Area). It also contains the renamed identifier attributesfrom the input layers: FID_StreamBuf and FID_NestBuf.In the exercise introduction , you saw that attributes are not populated for every recordin a Union attribute table. Identifier attributes , however, are completely populated.Every record ti the Attributes of NoCutArea has not only an OBJECCTID value, butalso an FID_StreamBuf value and an FID_NestBuf value-regardless of which inputfeature is spatially coincident with the output feature.For example, the first record in the NoCutArea table has an OBJECTID value of 1.This value is the feature's new identifier. The record's FID_StreamBufvalue is 10. Thismeans that the feature coincides spatially with the feature that has the OBJECTID of10 in the StreamBuf table. The record's FID_NestBuf value is -1. The -1 value meansthat the feature does not coincide spatially with any feature in the NestBuf ayer.Later in this exercise, you will see how to use this information to your advantage.

1 3 C l o s e t h e table. Turn on the StandsF ayer.E d e E d Y w @ e 4 o o . s 4 (9808 $ele [[bn Tads 99daw LbbOo h+n-4

z- u 9

8 keMfuD Lao eF

an0pno=-inOroe10010BxoattOver lay%s l n l e rs e ctJ 0#480

^ 8,0x15[96Jfer 1 4 J p b 0 ,0 9 Bu f f e r

e44-9 T0010 C9800 roan Todo. 0988 Men8gHner 1000

00000Mn91001,Urea 6so 5 09 T001

M]bde T0Ok. Oltidmenv ,1001,05500ea 5c here& rc s T001s

SOrve^ l0o^s SPa6a1510 ,050,1001

.414 M- k ?

DiW4y Sauce 50109805 F4va4e, IMaI S4aphRwea0.nJ4ra.:w - R u A.. onda

568138 08 6249778.55 901980

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A n a l y z ing spatial clan, 331

To find the harvestable land, you will union the NoCutArea layer with StandsF. Afterthe overlay, you will be able to select the polygons that represent harvestable areas.

14 In the ArcToolbox window , dou b le-c l ick the Union tool.15 C l ick the Inpu t Features d rop-down ar row and cl ick NoC u tArea to add i t to the lis t ofinput layers. Do the same for StandsF.16 C l ick the Browse b u t ton next to the Ou tput Featur e C lass box. In the Ou tput Featur e

C lass d ialog b ox, navigate to \GTKArcGIS \C ha pte r l2 \MyData and doub le-c l ickMyTongass.mdb.17 In the Name box, type F ina l . Ma ke s u r e your dialog box matches the following graphic,then click Save.

output Featewe cILookin ' MyTongassmdbNameL] GoshawkNestsJ LeaseFJ Leases

N e s t B u fJ NestsF

NoCu tAr ea]Stands

J StreamBufJ StreamsJ StreamsFName; FinalS a n e a s t y p e . F e a lu re d a s s e s

P e rs o n a l G e o d a t a b a s e F e a t u re C la s sP e rs o n a l G e o d a t a b a s e F e a t u re C la s sP e rs o n a l G e o d a t a b a s e F e a t u re C la s sP e rs o n a l G e o d a t a b a s e F e a t u re C la s sP e rs o n a l G e o d a t a b a s e F e a t u re C la s sP e rs o n a l G e o d a t a b a s e F e a t u re C la s sP e rs o n a l G e o d a t a b a s e F e a t u re C la s sP e rs o n a l G e o d a t a b a s e F e a t u re C la s sP e r s o n a l CF!?dot ns n =eature C assPersonal Ssada'et^ae^. Feature Class

01

_ JSane

Cancel

Leave the Join Attributes dro p-down list set to ALL. This time you will include all inputattributes in the Union layer. ( You will need attributes like StandValue and ValuePerM eterto recalculate the stand va lues in the next exercise.)

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332 Sectzon 5: Analyz ing fature rrlarion hips

1 8 M a k e s u r e your d ia log b ox matches the fo l lowing graphic , then c l ick OK.

0 ~~J reahae Can'.,fSRIPess'. GK _G Cnaoter 361DBZ,N330011.fl \=irat eAL

%Y Tdrarca (lymw)

J

19 When the operat ion is completed, c l ick C lase on the progre ss window.E de 01l Vb w 50o15oe o 9 40111 361003064 30010 96111010 Calp

L a r e r a1 -PIMi- 0 N0003Area- ! so-ea,^BJDrveste0f0a O Nes3S F

] :.' :-4su :- R4

-'. u SbeemS aC on Og r aphy 00dz^ C6nverslon T641s Data Manegesnent Toda

m SeM Geoco n q 1 0 1 1 5fJ L4ear Referencnq TodaLea eF Mdxle Tods MO A i d u n 1 0 00 0 T o d a' Samples aY S c l g m a t i c s T o d a Servn 16010

Dapby 56wce BelxGm- wrAea Irle- 5ewd R-A 1. 0 e sbaW q-RA

3 r ]! Ah1585153 17 6236139 7M .-

The Final layer, which has more than 5,000 features, is added to the rnap. At thisscale, it's hard to tell if you're looking at the result of a spatial analysis or just a plate ofspaghetti. In a moment, you'II zoom in, but first you'11 look at the actribute table of theFinal layer.

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Analyzing spatial datn 333

2 0 In t h e t a b l e of contents, r ight-c lick the Final ayer and c l ick Open Att r ibu te Tab le. A t t H b u t e s o f F i n a l

OBJECTID' Shape FID NutArea 1 FID NestBuf FID StreamBuf FID Stand*F I.^ 1Poa_on11_1121pgn210-1Poygon4 - 12-1Polygon 1 35 Polygon -1 1 4 -16 Polygon 10 -1 2 1

7 Polygon 14 -1 2 7 -18 Polvoon 18 -1 33. -1

R e c o rd : NJ 1 f ^ I Show: All 5elected Records ( 0 o u t o f *2000 Selected) 11The FID_NoCutArea attribute is the renamed OBJECTID from the NoCutArea ayer. Ifa record has a value other than -1 in this field, it means the output feature coincides spa-tially with a buffer feature; in other words, it's not harvestable. If a record has the value -1,it means the output feature does not coincide with a buffer and therefore is harvestable.The harvestable area of lease F, therefore, is the area composed of all polygons in theFinal ayer that have the value -1 in the FID_NoCutArea field.

21 C lose the At tr ibu tes of Final table. C lose ArcToo lbox. In the table of contents, tu rn o f fal layers except Final.

22 Cl ick the Bookmarks menu and c l ick C loseup.FM. [d4 Y- eooknuru t n s m , 1*M . n Lwis 1~14 1

-D

ONe*F

=i O 0mmsF=. O 5ter1 F7LL. O LeaseO

591628.St 6245594.; Matas

334 Section 5: Anrtlyz ing frtture relationsbips

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To see which areas can be harvested, you will turn on labels.23 In the table of contents, dou b le-click the Final ayer . On the Layer Pro per t ies d ialogb ox, c lick the Lab eis tab. C heck the "Lab el featu res in this layer" check b ox. C l ickthe Label Fie ld drop-down ar row and c l ick FID_NoCutArea. Make sure your d ia log boxmatches the following graphic, then click OK.

1. S""Labd F,,1

loAii . rTJ-) HP(_yl -

ona. pt i Retidr dLZbdstykP lmer n r A Piapalros .. 5cdevga J Laid59

On the map, polygons labeled -1 represent harvestable arcas,aJ-1 i.-am -1 I+ ',

flan R - u-A on t0-aqA-!h. ^$91010 66 6245551 9] Ma ers

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A n a ly z in g sp a tia l d ^ ^ ^ . : 335

It would be easier to read the map if you used colors instead of labeis. Applyingsymbology is not part of this exercise, but you are welcome to do it on your own, usingwhat you learned in chapter 5. Your result might look like this:

9a Ede exw @oewnena Itrwt ki t L Lw t I *

-F.wF1o neGaaea

l & v e s t a d e- uMCArea

w

swrca san Irn.O A oaid

ii :S! .'- t3 u - R?

5 271,71 6?9.8I4

In the next exercise, you will recalculate the Final layer's StandValue attribute to get anaccurate total value for harvestable land.24 I f you want to save you r work, save i t as my _ exl2b . mxd in the \GT KAr c GI S \ Chapt er l2\M yData folder.2 5 If y o u a r e continu ing with the next exercise, leave A rcMap o pen. Otherwise, exit theappl ication. C l ick No if prompted to save you r changes.

336 tiertiosl 5: Arzaiyzirrtrfatrare relationships

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C alculating attribute valuesYou can write an expression to calculate attribute values for al] records in a table or just forselected ones. For numeric attributes, the expression can include constants, functions, orvalues from other fields in the table. For text attributes, the expression can include characterstrings that you type or text values from other fields.

E x e r c i s e 1 2 c'The graph you made in chapter 11 showed the timber value of lease F to be about1.5 billion dollars. In this exercise, you'11 adjust that value to take into account onlyharvestable arcas. You'lI creare a definition query to display these arcas, then vou'11recalculate stand values to determine how much the total harvestable arca is worth.

1 In ArcMap, open exl2c.mxd from the C : \ E S R I P r e s s \G T K A r c G I S \Chapterl2 fo lder ,Eb E& ~~

~ ki - Ioots Wn tlmP00la a

o----zlsox1Pr~n - R u - A- ''.. P-de

- :?.. - 4 0 . !?

5902.2262199)23 Metas _.

The map contains the Final layer you created in the last exercise.In the last exercise, you saw that harvestable arcas have the value -1 in theFID_NoCutArea field. Using that value, you will creare a definition query to displayonly the harvestable arcas.

2 In the tab le of contents , doub le-c l ick the Fina l ayer . In the Layer P roper t ies d ia log b ox,cl ick the Def init ion Q u ery tab .

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Analyzing spatinl ,,a r,i 337

3 C l ick Query Bu i lder to open the Query Bu i lder d ia log b ox.[ DGJECTIDI[FID SiandsF[[ LeDSeIDI,SImdVluel[ValuePeMetei[, S I a n d I D l

DI([ NX

T_ ri

"1Gel U--- Velues GoTO F-SELECT' FRDM Fne l WHERE 1

_Heb Los 1DK

4 In the Fie lds b ox, sc ro ll down and dou b le-c l ick [FID_NoC u tAreal to add i t to theexpress ion b ox. C l ick the equals (=) bu tton, then c l ick Get Unique Va lues. In theUnique Values l ist, double-click -1. Make sure your expression matches the followinggraphic, then click OK.F I D _ N o C u t A r e a ] = -1

The query displays in the Definition Query box.G m m d 1 S a u c e 1 S ~ - D p W y 1 s y o b o b . 1 Fi d d s D~- auo,y l Labdo 1 Joms & Rewe:1 HTML Popo 1

D ef i r n - Qa yiDJ:oD.u?peal=-1

G u e r y Budtio__

yzing f ^ a tu re r e la t iOl s h /p s38 s ction 5: Anal

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mxNC)(D

C- )dciy

U C ID l1rto -cC D DncCD

5 C lick OK on the Layer Pr operties dialog box.

On the map, only features satisfying the query are displayed. The layer attribute tablewill show only the records corresponding to these features.Now you'll update the StandValue attribute for these features.

6 In the table of contents, r ight-cl ick the Final ayer and cl ick Open At t r ibu te Tab le.OBC17MShepe m~LeweU!o~1YYUdnMeas~MoCMFe

1 807404 1 F 5 38561 63 305 -12 807404 2 1 4 41475 2J 3l9 -13 Pd5904 3 F 310103 64 32 8 -14 Po ' 4 4 F 4.93165 52 338 15 P0580n 5F 06950251 26 337 -16 P345840 6 F 2401891 25 345 -1e P0 440 0 8 F 321903 21 364 19 500400 9F 486889: 42 358

08086 t4 _ 0 9 n Show l A S~ed R e o o , d e ( 0 oU o 3 7 2 Sekcted( Optima -

The table shows 372 records, rather than the original 5,439.The values in the StandValue field need to be updated. Although some of the originalstand polygons were preserved intact in the Final layer (and still Nave correct standvalues), many other stands-all those that were overlapped by a nest or streambuffer-were split in the last overlay. The resulting smaller polygons have correct areavalues because ArcMap automatically updates the Shape_Area attribute, but their standvalues, which were simply copied over from the StandsF table, are wrong. To correct chestand values, you will multiply the area of cach feature by its value per meter.

7 Right-click the field name StandValue and click Field Calculator. Click Yes on themessage warning you that you cannot undo the calculation.The Field Calculator dialog box opens.

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Anza)yzing spatial data 339

8 In the Fields b ox, dou b le-click Shape_Area to add it to the expression b ox. Click themultiplication (*) button. Again in the Fields box, double-click ValuePerMeter.mTYPe: Fu888rrOBECTDY' b Ab)Nurti erFID_RmdsFeaseDT51dn9A l , 1 }c o z ( )

5tand0aWe 6xP Uc Date Fx ( 1Stand[D ^W( 1FID_NOCdpfeaFID 5treerndf Sm i.70x1 ) JFf0_Nest01SapeAea 1 1 1 2 j5 t a d , e = r - 1 J - Jr5hape _ A reaj ' rva wMeter]

5 a . e . . . I1

a 1This expression will give you the updated stand values in dollars. In the table, however,the stand values are expressed in millions of dollars.

9 C l ick at the b eginning of the expres sion and type a n open ing paren thesis " ( " fol lowedby a space. C l ick at the end of the express ion and type a sp ace fo llowed b y a c los ingpare nthesis " )". C l ick the d iv is ion ( /) b u t ton. Type a s pace an d type 1000000. Makesure your expression matches the one in the following graphic, then click OK.Sanddaue=- Advanced( [Shape_Alea] [ValuePerMeter ] 1 1 1000000

The values in the StandValue field are recalculated.sAtH.dn 81 Final

OB.BCT8Y Shape FD_S nd F Leasew _ S 1a11d04b e FIDNoC.W- C1 Pd,9on 5.36561 63 3052 P d y 9 00 2F 441476 27 3083 Po40 on 3 F 310103 64 32 81P~ 4F 493265 52 3 385 P01yg0n SF 0645025 26 33 76 PoIygon 6; F 240189 25 34 57. Pdygan 7F 7.33754 27 3605 Pdy9an 8F 3 21903 21 36 49 PdY9nn 9IF 486689 421 358 1

4] ]Retad 14 4 0 J rl Show A9 Sebded Recado (0 x i d 3725ekctedl

340 S ect ioz z 5 : A z u t l yz i z z g f ^u z tur e r e la t io t t+hi j s

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10 Rig ht -click the StandValue field name and click Statistics.FX

F i e l d

5 tatistir_sCount: 372M n i m u m . 0.013003M a x i m u m 11111355Sum 1052 08379Mean 2.828182Standard D eviation: 2.078342

LJ

Frequency Dis t r ibut ion

The sum of the values is 1,052.08379. The harvestable value of lease F is therefore justover a billion dollars-about two thirds of the original calculation shown in your graphfrom exercise llb, step 10.

11 C lose the Stat ist ics windo w and the tab le.Your company will use this information to make a competitive bid. It's a big investment,but tree harvesting is expensive. You Nave to move heavy equipment finto the arca, supplythe labor force, and eonstruct roads.A more detailed analysis would consider additional factors, such as the locations of existingroads, the slope of the land, and other protected arcas like stands of old-growth trees.

12 If you want to save you r work, save i t as my _ex l2c .mxd in the \ GTKArcGIS \C h a p t e r l 2\M yData folder.In the next chapter, you'll launch ArcMap from ArcCatalog. So even if you are continuing,you should exit ArcMap now.

13 Close ArcMap. Cl ick No i f prompted to save your changes.

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Analyzin^l spatial da,! 341

B u i ld i n g a s p a t ia l m o d e lIn chapters 11 and 12, you carried out many spatial analysis operations, such as Dissolve,C lip, Buffer, and Union, using ArcToolb ox. These operations were not ends in themselv es,b u t steps in a larger a nalytical process. Before u nder taking a similarly complicated GISproject, you might find it useful to draw a flowchart or diagram that identif ies the goaland the analytical steps that lead to it. What data will you need? What geoprocessing willbe requi red? Which outputs wi ll become inpu ts to new operat ions?In ArcGIS Desktop 9, ModelBuilder is available to help you do that. ModelBuilder providesa des ign window where spat ia l analys is operat ions can b e def ined, sequ entia lly con-nected, and carried out, al with the use of drag-and-drop icons. ModelBuilder is both aworkf low d iagram ming tool and a pro cessing env i ronment. It keeps t rack of the opera-t ions that you r un , thei r resu l ts, and thei r interdepend encies. It gives you a conv enientway to bu i ld a large project from i ts component parts and ru n i ts processes sep aratelyor together. Your model can b e changed at any t ime to incorporate new d ata, add newcondit ions, or try different assumptions (best case, worst case, what i f. . .).Chapter 20 in this book revisits the Tongass Forest Lease analysis and shows you howto design and execute the same project in ModelBuilder.

+ H aweat Profd ab i i tyModel Edd View Wmdow Help

e , ^ e r ( z )

ipBulle,

sueanB: 1f f

_ u x

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Section 5: Analyz ing fea ture re la t ionships

C h a p t e r 1 3P r o j e c t i n g d a t ai n A r c M a pP r o j e c t in g d a t a o n t h e f lyD e f in i n g a p r o j e c t io n

k

344 lectiott 5: Analyzrng fainre relationshiPs

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L o c a t i o n s o n t h e e a r t h ' s s u r f a c e a r e d e f i n e d w i th r e f e r e n c e t o l in e s o f l a t it u d e a n d l o n g i t u d e .Latitude unes, or para llels , run paral lel to the equator and m easure how far north or southyou are of the equator. Longitude unes, or meridians, run from pole to pole and measurehow far east or west you are o f the prime meridian ( the meridian that passes throughGreenwich, England).

The mesh of in te rsect ing para l le isand m er id ians is ca l led a g ra t icu le .

Athens, GreeceLatitude = 3756' north ( o f t h e e q u a t o r )Longitude = 2339' eas t ( o f t h e p r i m e m er i d ian )

Latitude and longitude are m easurements of angles , not of distances . Latitude is the anglebetween the point you are locating , the center of the earth , and che equator. Iongitude isthe angle between the prime meridian, the center of the earth, and the meridian on whichthe point you are locating l ies. Because lati tude and longitude are an gles , their values areexpressed in degrees , minutes , and seconds.

N

450' 0' N lat i tude60 0' 0 " E long itudeWhy use angles instead of distances? B ecause as mer id iansE c o n v e r g e t o w a r d th e p o t e s , the d is tance between themshrinks . At the equator , a d e g r e e o f l o n g i t u d e is a b o u t 6 9m i l e s ; a t t h e 4 5t h p a r a l l e l , i t ' s about 49 mi les ; a t t h e n o r t hpole, i t 's zero . In o ther words , there is no constan t d is tancev a l u e t o r e p r e s e n t t h e s p a c i n g b e t w e e n a p a i r o f m e r i d ia n s .T h e a n g l e b e t w e e n a p a i r o f m e r i di a n s , o n t h e o t h e r h a n d ,s t a y s t h e s a m e .

Starting from the equator , latitude values go to +90 at the north pote and to -90 at thesouth pole . Starting from the prime meridian , longitude values go to +180" castward and to

-180 westward. (1he +180 and -180 meridians are the same.)

Projecting data in ArcMii, 345

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Latitude and longitude are the basis of a geographic coordinate system, a system that defineslocations on the curved surface of the earth. Because different estimates have been made ofthe earth's shape and sine, there are a number of different geographic coordinate systems inuse. Although they are similar, the precise latitude-longitude coordinates assigned to locationsvary from one system to the next.

Some geograp hic coordinatesystems are based on theassu mption that the earth is asphere. This s imple mod el isadequate for many purposes.

Most geographic coordnate systemsare b ased on the assum ption thatthe earth is a spheroid. (A sp heroidis to a sphere as an ov al is to aci rc le.) This is a more accur atemode l becau se the ea r th bu lgessl ightly at the equator and isf lattened at the potes. H istor ical ly,severa) spheroids of varyingdimensions have been calculated.(This picture greatly exaggeratesthe flattening, which is really only afract ion of a percen t.)

To make a map , the earth mu st be represented on a flat surface . This i s accomplished by amathematical operation called a map projection.

A m ap pr oject ion f lat tens the earth. Locat ions on the earth are system atically assigned to newposit ions on the map. This can b e don e b y many dif ferent me thods ( inf ini tely many, in fact) .

346 5ce ct io rr 5: Aricr ly z i rr ,^^ature relatioustips

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Locations on a m ap are defined w ith reference to a grid of intersecting straight unes . Oneset of unes run s parallel to a horizontal x-axis ; the other ser run s parallel to a vertical y-axis.The coordinares of any point are expressed as a distance value along the x-axis and a distantevalue along the y- axis (from the intersection of the axes).

10

-10

-15-10-50 5 10 15

A t h e n s , G r e e c ex = 2,633,000 meters ( along the x-axis)y = 4,436,000 meters ( along the y-axis )

On a f at map, coordinate valuesrepresent d istantes rather thanangles. Here, the u nits are mil l ionsof meters.

A projected coordinate system, a system that defines locations on a flat map, is based on x,ycoordinares. The x,y coordinares of any given point, such as Athens, depend on the mapprojection being used, the units of measure (meters, feet, or something else), and on wherethe map is centered. lf Athens is made the center of che map, for example, its x,y coordinareswill be 0,0. Thus, the number of possible projected coordinate systems is unlimited.Since the world is more or less round and maps are flat, you can't go from one to the otherwithout changing the properties of features on the surface. Every map projection distorts thespatial properties of shape, area, distante, or direction in some combination.

The Mercator projection preserves The sinusoidal projection preserves area butshape but distorts area. On the map, distorts shape. The proportional sizes of GreenlandGreenland is much larger than Brazil, and Brazil are correct, but not their shapes.but on the earth it is smaller.

P r o j e c t i ng d a t a i n A r c A l , , i , 347

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The W inkel tr ipel project ion balances d istort ion.No s ing le proper ty is fa ith fu l ly p reserv ed , b utnone is excessively distorted.

The azimuthal equid istant project ionpreserves t rue distance and di rect ionf rom a single point ( in this case, Athens)to al l other locat ions on the map.

Your choice of map projection lets you control the type of distortion in a map for your areaof interest. If you are mapping an area the size of a small country, and using an appropriateprojection, the effects of distortion will be insignificant. If you are mapping the whole world,distortion will always be noticeable, but you can reduce or eliminate certain types of distortionaccording to your purpose.For more information about coordinate systems and map projections, click the Contents tabin ArcGIS Desktop Help and navigate to Mapping and visualization > UsingArcMap> A bout coordinate syste nz s and map project ions.

348 )eetiort 5: Aoalyzia^ f^^trure reI itii i l3hips

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P rojecting data on the f lyEvery spatial dataset has a coordinare system. lf it's a geograph ic coordinare system, its featuresstore latitude-longitude values . If it 's a projected coordinare system, its features store x , y values.Besides storing feature coordinares, a datases contains other coordinate system information.The definition of a geographic coordinare system, for example, includes the dimensions of thesphere or sph eroid it's based on and other details. The definition of a projected coordinate sys-tem includes the projection it's based on , the measurem ent units, and other details. Each pro-jected coordinare system is also associated with a particular geographic coordinare system, sinceits x,y coordinares were at som e time projected from a set of latitude -ongitude coordinares.You can find the coordinare system of a dataset by clicking the metadata tab in ArcCatalog.You ca n also find it in ArcM ap by clicking the Source tab of che Layer Properties d ialog box.

C o r t e n t s 1 R e v i e w M e t a d a t a

World Countries ( Generalized)S h a p e f i l e

D e s c r i p t i o n At t r ibut esHorizontal coordinate system

projected coordinate system flama World_Miller_CylindricalGeographic coordinate system namer GCS_WGS_1984Details

Bounding coordinatesHorizontalIn decimal degrees

West -179.999989

This World C ountr ies shapef i le hasa projected coord inate system. Youalso see the geographic coordinatesystem from which the projectedcoordinates were der ived .

When you first add a layer to a data frame in ArcMap, it displays according to the coordinatevalues of its features-geographic or projected, as the case may be.What happens when you add a second layer to the data frame? If it has the same coordinatesystem as the first layer, there's no problem. But what if its coordinate system is different?Since coordinates tell ArcMap where to draw features, there is a potential conflict.ArcMap resolves this conflict automatically. You already know rhat a map projection is amath operation that changes geographic coordinares to projected coordinares. ArcMapknows the equations (forward and backward) for hundreds of projections. So when the sec-ond layer you add has a different coordinate system from che first, ArcMap changes Layer 2'scoordinares to match Laver ]'s. This process is called on-the-fly projection.

Pr o je ct io g data in ArcNLrp 349

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How does it work? Suppose you add a layer of world countries to a data frame. Say it's inthe Miller cylindrical projected coordinate system. ArcMap stores the information aboutthis coordinate system (and the geographic coordinare system it's based on) as a property ofthe data frame. Suppose you next add a layer of world capitals in the sinusoidal projectedcoordinate system. ArcMap checks the data frame properties and knows it can't display thislayer according to its sinusoidal coordinates-it has to change them to Miller cylindricalcoordinares. To do Chis, it looks at the geographic coordinate system that the world capitalslayer is based on, "unprojects" the sinusoidal coordinates to latitude-longitude coordinates,and then projects these latitude-longitude coordinates to Miller cylindrical coordinates. Theresult is that the capitals display in their correct relationship to the countries.Now suppose you add a third layer of world rivers that is in a geographic coordinare system.The process is simpler. All ArcMap has to do is project the latitude-longitude coordinates toMiller cylindrical coordinates. All three layers now occupy the same "coordinate space" anddisplay in correct spatial alignment, even though the coordinates stored with the features aredifferent for each layer.

Source dataCountries in Miller cyl indr ica l PC S

R ive r s i n GCS

JaJ1JThe data f ram e adop ts the coordinate system of the fi rst ayer add ed to i t( in this case, Mil ler cylindr ical). Layers add ed su b sequ ent ly are projectedon the fly to this coordinate system.You don ' t have to u se the coord inate system of the fi rs t ayer you add-this is just the ArcMap d efaul t . You can assign any coordinate systemyou want to the data f rame (ev en one that none of the layers have) andal layers wi l l be pr ojected to match i t .

On-the-fly projection doesn't change the feature coordinates of the datases on disk, or thedataset's coordinate system information. On-the-fly projection has effect only within a singledata frame. If you were to add these same three layers to another data frame in the samemap document-but if you added the world capitals layer first-all the layers would displayin the sinusoidal projected coordinate system.

350 Section 5: Atzalyrzing leatzzre reIatinaz.;hips

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On-the-fly projection works best when layers are based on the same geographic coordinaresystem. If Laycr 2 has a different geographic coordinare system fi-om Layer 1, you'll get amessage like this:

Warning:The following ayer: citieshas a geographic coordinate system that differs from other data in the mapo from the current map projection.

You may need to select a different geographic transformation than the oneautomatically chosen for you in order to avoid alignment o accuracyproblems with the data.OK OK lo all

r Don ' t warn me a g a i n i n C h i s s e s s i o nr Don' t warn me again ever

Ik

"Ihe message rells you that ArcMap can display the ]ayer, but that the spatial alignmentprobably won't be just right. That's because ArcMap can't convert one geographic coordinatesystem to another without some help from you. Without that help, the data will be mis-aligned to the extent that the geographic coordinare systems differ from each other. This dif-ference is usually too small to notice at the scale of a world map, or even a continental map.But if you are making a map that demands highly accurate feature positioning, or if vou aregeoprocessing the data, vou will first want to convert one layer's geographic coordinare systemto that of the other.This operation is called a geographic coordinare system transformation (or a datumtransformation). ArcMap supports it, but the process is not described in Chis book. Formore information, click the Contents tab in ArcGIS Desktop Help and navigate to Mapprojection and coordinate systems > Geographic transformations.

Exerc ise 1 3aYou work for the U.S. Census Bureau and are creating a map of the United Statesthat shows population chango between 1990 and 2000. The map will have three dataframes: one for che lower forte-eight states, one for Alaska, and one for Hawaii. 'Ihesame shapefile of U.S. states (in a geographic coordinare system) will be used in allthree data frames. You'll set a different projected coordinate system for each data frameand ArcMap will project thc data en the fly.Why use three data frames instead of just one? Showing all fifty states in the same dataframe would mean including all the space that separares Hawaii and Alaska from thecontiguous forty-eight states. You would have to zoom out so far that little states wouldbe har to see. By putting Alaska and Hawaii in their own data frames, however, youcan zoom in on them and move them close to the other forty-cight srares.

Projecting data in A rcltl,r,') 351

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U.S. Populat ion Growth1 9 9 0 - Z o o sc_y.

The United Sta tes drawn in a s ing le da ta f rame.

U.S. Population Growth1 9 9 090-zoco

The United States drawn in three data frames.Alaska and Hawaii aren't shown in trueproportion or at true distance from the lowerforty-eight states, but that isn't important tothe purpose of your map.

You will use three versions of the Albers equal area conic projection. This is an excellentgeneral-purpose projection for arcas in middle latitudes, especially those having aneast-west orientation. It preserves the spatial property of area, which means that mapfeatures are displayed at their true proportional size. Shapes are only minimally distortedfor an area the size of the United States.

1 Star t ArcC atalog. In the ArcC atalog t ree, dou b le-click the connect ion t o C : \ESR IPr e s s\GTKArcGIS . Dou b le-cl ick the Chap ter l 3 folder. Double-click t he Dat a folder.FM E8 0io So rauk Wkrdon H*ss - x4C k?l vLocabore C -1ESFIPress\v T lacGISICt.piet131Da

s

Ca Ie * , 1 Pwvw 1 Mdadata 1j o C : 1i C:W5RNk asicrenr.c l5 N- fyp.J ch al F a s t c . n e s H r L a y e ,J Chapt I ..WFastCk 1," SFa d

.:J QiapteAS Statez.h, L"f l J Q hapter0 5 E]Rat-hP 5f reJ Crupter07

[tl 'J ChaPt ioJch eoeu J oiaotwD J chapterl1J J Chaptdl2- J Ch~13

352 Seection 5: Ana1yzing fature relationsbips

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There are two shapefiles: FastCities and States. Each has a corresponding ]ayer file. Inthis exercise, you'11 use the States data. (You'll work with FastCities, which contains thefastest-growing city in each state, in the next exercise.)

2 In the catalog window, click S t a t es . Iy r and c l ick the P rev iew tab.

Montana

T e x a s

The layer has been symbolized with a color ramp that shows population change. Thestates, displayed according to their geographic coordinates, are distorted both in shapeand arca. The northern boundary of the United States appears to be a straight line, forinstance, while Alaska looks stretched out. Montana seems to be roughly the same sizeas Texas, while in reality Texas is nearly twice as large.

3 C l ick the P rev iew d rop-down ar row and c l ick Tab le. Scro l l to the r ight.C~44 P49)W 1 Metadala

~M POP2000 Nn1nCN4n0E P44Ch~ 1 -4866692 707851E 1027429 21 1799065 902197 103130 12,912279281 127492" 3.86388001 642200 3400 0. 5596004; 754644 58840 6. 54535881 7078515t 4091169 7076516 40194a 1906 899. 61006749 1293953 287204 26 55627581 608827 46069 824375099i 4919479 544380 1242842321; 3421399 579078 2041109252 1235766 1265342776755 2926324 149569 586 0 16 425 5349)07 332672 SSu

Recad. J4i 111 l Sh- Al RA (,4SMOPThe table has 1990 and 2000 population figures for each state, as well as the populationchange in raw numbers and percentages. Every state grew during the decade. 'Ihe layeris classified and symbolizcd on the PctChange attrihute.You'll confirm that the States shapefile has a geographic coordinare system.

Projee t in g d a ta in A rcvA LI / 353

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4 In the catalog tree, click States .shp. In the display, cl ick the Metadata tab.5 In the metadata window, cl ick the Sp a t ia l ta b . ( I f you don ' t s e e the b lue ta b s in your

m et ad at a , display the Metadata toolbar i f necessary, c l ick the Sty lesheet drop-downarrow and cl ick FGDC ESRI.)C o n t e n t s i P r e v i e w M e t a d a t a ,

StatesShapefile

i

D e s c r i p t i o n

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ArcMap opens in layout view.Eb Edt ~ @oabnar0s lasas daaoa Took W.do.o tmp

0lO L o . .e r 4 e

53 :P..+-4o R?

U.S. Popu lation GrowthP l a s k a 1990- 2000

Lower 48

Hawai)^ .a.. ,

o^cw soy sd ao ^a'o . J - iiJLkar: u - R '1 u - A

0890,010

The map contains three empty data frames: Alaska, Hawaii, and Lower 48. Lower 48 isactive. A titie and legend have already been added to the map.You'1l add the States ayer to each data frame, zoom in appropriately, and apply mapprojections to che data frames.

7 Pos i t ion the ArcC ata log and ArcMap windows so you can see the cata log t ree and theArcMap tab le of contents.8 In the catalog tree, click States.lyr and drag it to the bottom of the ArcMap table of

contents. Click the ArcMap title bar to bring ArcMap forward.

r -J Chapter03jChapterO4.8J J Chaple,05J ChpterO6+: J ChaptecO7+ J ChpterO8+ _J ChapterO9

+ J Chapleri O+ _J Chaptertl+ J Chapterl2- J Chapterl3

J Data0 FaoICitieoJyrF a s t Cit ies . shp^0 Stales.ohp

Li Li MyData4aj ..13e rood,L111 ..1 3b ..d. J Chapter14o J Chapterl5:. J Chapte,16 -J

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The layer is added to the table of contents and displays in the data frame. It looks asit did when you previewed it in ArcCatalog. You'll use a bookmark to zoom in to thelower forty-eight states.

Ek dt Yrew Ooc0rn rks l t 5elucmn 1ook ~troin - + 1 sa7z156 :P. t& al in: k?

-1-2-, 110.......

U.S. Population Growth1990. 2000

Hawai l

rl u - A - jo anal 10- a ! uA-

9 Click the Bookmarks menu and click Lower 48.U.S. Population GrowthPaska 19902000

Hawao

356 ' eet io n 5: A nalyzing f atuve relat ionships

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10 In the C ab le of contents, dou b le-click the Lower 48 data frame. In the Data FrameProper ties dialog box, cl ick the C oordinate System tab.~M-Gramos EaerIR~Frene

General 1 Dat,F,ame Cond4te System I I^mndonCvrert coadnate syst em:GCS_eMf^AmerKet_ I 9> dDats,e U_N0rth_Wncrrm_1983

L5dect e rar3wtesystem.

J F a t o r t es+ -1 Preirt dJ Latees- '.j ustan>

SeeedPo teon 1Sed. 1 M. Cache

TN9 W

A& T. F~

By default, the data frame is set to the coordinate system of the first layer added to it.As you saw in step 5, that is GCS_North_American_1983.11 In the Select a coord inate system b ox, c lick the plu s s ign next to Pre def ined.

J E vJ Predefixd'.. J Geo4~ Coadnale SyskmsJ P e a ie d e d C m u t e S y s t a n aJ Lqe sJ

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A8 on Gto501 , Edenl Rect98 s Fleme Sien and PoslrnGe n e ra l Gala Faene CowdnAeSYSkmIluniW qn GW. 1M,Cechacuren rowena< e:yaem:USA Cun[guous A l b e r s E W a l , f r e a C o r t l ePro98tm AbersFakeEastrO : 0.000000Falce Mrllinq : 0.000050Cer d r a l M endan :-96.000770S ta rderd P ma1e1 1: 29 .500000Standard Per d 2:45.500500Latdude Of igin: 37.500000Linear 1910: Meter

Clear

LGCS Ng r th Anwkm 1983Dato,,: 0_Nerth_Anean_1963JJ Trarsfwmatnee... 1seled a caudnete ey:

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contents, r ight-c lick the H awaii data f rame and cl ick P aste Layer(s) . Again in the tableof contents, r ight-click the Alaska data frame and click Paste Layer(s).Efe dk V. Boohnarks ;nsert lekctl n Iods wndwr ryepu l u , {. z' 7975[ E10A61=

vucUx G,owu,IJI-1010-20X20-67

- O Hawa- States

Percent Growth1-10

10-20s 20-67

0 tewe aeMPe rce rc Gro wt h

.1 10U 10- 20U20-6]

D,:dar iE J s d e ^ a n i i Dt 11-2 ra wi n 0 R u - A- . loAsid

i :z s_*m R?

2.20 0 30 0

The States layer now displays in all three data frames.16 In the table of contents, right-click the Alaska data frame and click Activate.17 In the table of contents, double-click the Alaska data frame. In the Data FrameProperties dialog box, click the Coordinate System tab if necessary.

Amolaban G 2o2P 6 Edent 076 r0177 Frame 0ra and Po6 rGe n m a l 1 Da l a F ra m e CO~ SYNem l Ipunnatgn G,,& 1 M70 CacheCvreM c oordna te sY s tem' .GCS_North_Amerkan_1983D 0 1 2 r r : L_bHh grnerpen_1903

S e lec l a c aadna te s rs tem' ,J FavontesJ [727,2< es tom>

Medir..

1

JJ

Add Ta Favorkes 1

-7-1 C..

OK

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As before, the data frame's coordinare system is set to GCS_North_American_1983.You'll ser an Albers projection developed for Alaska.

18 In the Select a coord inate system b ox, c lick the plus s ign next to Pred ef ined, the pluss ign next to Projected C oord inate Systems, the p lus s ign next to Cont inental , and theplus s ign next to Nor th Am er ica.19 C l ick Alaska Albers E qual Area C onic. Make sure that your d ia log box m atches thefollowing graphic, then click OK.

A letion Grows 1 Extent Reot~ Frene Size and Po,U nGened 1 Data FrenM Cooidnte SYsl,n ( ilumndion Grids 1 Mae Cache 1C w t c o o r d i n a r e s y s t e m ' :NAD 1983 Alaska _AEers j Cba,Pratxtion: Al-a d s e . N o r l h l J: Oa.ac 7FC81 o JOr t nd .o O.000DJO^ C e r t rd Mariden: I 0000055.. StaMard_Peallel I: 55O000cSte+ded i_O,,l 2: OS.CQOLm0La W~lnea U^ UnJ T ' , W~M et er

GC5_Fbth h_ Ann 1983D a t u n : D N w N A m e r i c a r r_ 1 9 83iranstormatpns... I

5d o t a co wd a > e t e zy s t m n :J Asia Mody...J Ewope_j N o r th A mer n a

C a n a d a A b e rs Ep u a l A r f a C O n , cI a V O r t

C a n a d a l a m p e a r r a , F O r m a l C o r n c JH a wa i i A l b e s E, ,d A re a C o n i cNAD 1983 Srear alts Basen Alb,r Add To FayttResNAD 1983 c rea L ak es and S t L aoN o r t h A m e -K a A br a s E dua l A r ea C

.': North Amenca EASJ&ant Cono J

OK cancd APDO l

The layer is projected on the fly. Notice that the lower forty-eight states are set at an oddangle. The projection minimizes distortion for Alaska, but other areas may be severelydistorted. You won't show these areas in the data frame, so it doesn't master.

20 C l ick the Bookmarks me nu and cl ick Alaska.

21 In the sab le of contents, r ight-c l ick the Hawaii data f rame an d cl ick Act vate.

360 Sfectron 5. A r^^ r lyz irr , t^r turr reh^ t iorrships

22 Fol lowing the same steps you u sed for the other data f rames, set the coord inate system

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of the Hawai i data f rame to Hawai i A lbers Equ al Area C onic.23 C l ick the Bookmarks me nu a nd cl ick Hawaii .

U.S. Population Growthi99n- 1nan

Each of the three data frames now has a different projected coordinare system. (All usethe Albers equal area conic projection, but the projection settings are customized ineach case to represent the area of interest as accurately as possible.)

24 If you want to save your work, click the File menu and click Save As. Navigate to\G T K A r c G I S \Chapterl3 \M y D a t a . Rename the f i l e m y _ex l 3 a . m x d and click Save.2 5 If y o u a r e cont inuing with the next exercise, keep Ar cMap open; otherwise, exit theappl ication. C l ick No if prompted to save you r changes.26 C lose A rcCata log .

Projecting data in ArcALr,, 361

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D e f i n i n g a p r o j e c t io nFeatures in a dataset never lose their coordinares, but the dataset may not have the informationthat identifies its coordinare system. This can happen in particular with shapefiles, where thecoordinate system information is stored as a separare file (with the extension .prj).If you add a layer that is missing its coordinate system information, ArcMap will look at thefeature coordinate values before proceeding. If it sees that all the values are between 0 and180, it knows that the data is in a geographic coordinate system. It won't know which one,but it will make a default assumption that enables it to display the ]ayer with other layersalready in the data frame. (The spatial alignment probably won't be exact-just as when youadd layers that have different geographic coordinate systems-but it will usually be acceptablefor small-scale maps.)If ArcMap sees that the coordinate values are big six- or seven-digit numbers, it knows thatthe data is in a projected coordinate system, but again, it doesn't know which one. You'll geta message similar to this one:A Unknown Spatial RetereMe ? , x

T he lofowing data sou rces you a dded are miss ing spat ia l referenteinformation. This data can be drawn in ArcMap, but cannot be projected:FastCties.lyr

Li

2

JJ

The message tells you that the layer can't be projected on the fly. In other words, ArcMapcan add the layer to the data frame, but it can't change che layer's coordinates to match thedata frame's coordinate system. The result is often a serious display problem, because verydifferent sets of coordinates are trying to fit in the same map space. For example, if the dataframe is set to a geographic coordinate system, the unknown layer probably won't be visible(its projected coordinates are roo far apart from latitude-longitude values). If the data frameis set to a projected coordinate system, the unknown layer may display, but will probably beseriously misaligned. Sometimes you get lucky, though. If the data frame happens to havethe same projected coordinate system as the unknown ]ayer, the data will line up correctlyon its own.If a dataset is missing its coordinate system information, you should try to find out whatit is. This may involve contacting the data provider or looking through files for supportingdocumentation. Once you know the coordinate system, you can assign it to the dataset usingArcToolbox. This process is called defining a projection.

362 5ection 5: Arialyzin , t i1 f atuve re lh t t in i zsh ip1Exercise 1 3b

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In this exercise, you'll add a layer of the fastest-growing cities in each state to your map.From a colleague at the Census Bureau, you have acquired a shapefile of projected dataalong with a corresponding ayer file. Unfortunately, the shapefile is missing its projec-tion (.prj) file. This means that ArcMap can't recognize the coordinare system and isunable to project che data on the fly.After e-mailing your colleague, you have received the following reply:"Sorry that the projection wasn't defined. "Ihe FastCities shapefile is in the NorthAmerica Lambert conformal conic projected coordinare system."You'll add Chis coordinare system information to the shapefile with the Define Projectiontool in ArcFoolbox.

1 In ArcMap, open exl3b . m xd f rom C : \ E S RI P r ess \GT KAr c GI S \ Chapt er l3 .F1e [8 y~ Boc&n ks Irsert ddatl,n tods Yfu , ndp

cent G,owth1-102020-62

.- - + 7 61 017-1% .J

U.S. Population GrowthA13ska 1990. 2000

Hwam

o,Duce ,eka onI. oJr-9 - R O - A - d a W FBt.-. .- IA dJ

_, ,... 5% 8 93 ln

The map opens in data view. The Lower 48 data frame is active.2 On the Standard toolbar, click the Add Data button,

Projecting data in A rcMaf 363

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3 In the Add Data dialog box, navigate to \ G T K A r c G I S \ C h a p t e r l 3 \ D a t a and clickFastCi t ies .Iyr, as shown in the following graphic. Click Add.Rdd DataLook in: J pala

jFastCities.shp4 States.lyrM 5tates.shp

N e m e: FastCties.lyi

LayerShapefi leLayerShapefi le

S h o w o f t y p e : Dataseisnd Lay ers ('.Iyr]

ri

AddC a n c e l

ArcMap warns you that the layer is missing spatial referente information.A Unknown Spatial Referente

1-1 t'=-1 3 1 - Qq

xThe following data sources you added are missing spatial referenteinformation. This data can b e drawn inArcMap, bu ( cannot be projected:

FastCities.lyr

u-

If you don't see the warning, that's okay. In your ArcGIS past, you may have comeacross the Warning dialog box shown on page 350 and checked its Don't warn me againever box. If you would like coordinare system warnings to appear again, run the Ad-vancedArcMapSettings.exe executable file, which is located in the Utilities folder of yourArcGIS installation. On the Advanced ArcMap Settings dialog box, click the Miscella-neous tab and uncheck Skip datum check.

364 ^ ( r t i o n 5 . i r tr ^ p z i rr g f e ^ 7 t r r^ e r ^ l a t i o n s f ^ r p 3

4 Click OK on the warning message.

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ArcMap adds the FastCities layer. At first glance, things appear normal. If you take acloser look, though, you'11 see that some cities are lying outside the U.S. boundary.The data frame's current coordinate system is the USA contiguous Albers equal areaconic (the one you set in the last exercise). From your colleague, you now know that thecoordinare system of the FastCities layer is North America Lambert conformal conic.ArcMap, however, does not know this.Because it couldn't project the FastCities layer on the fty, ArcMap simply drew thefeatures where their Lambert coordinares said they should go. But since these Lambertnumbers were being plugged finto Albers coordinare space, the locations are wrong. (It'ssort of like digging for buried treasure in the right place on the wrong stand.)As it happens, the Albers and Lambert coordinares for the United States are not hugelydifferent; therefore, although the layers don't align correctly, you can at least see themboth together.

i You'11 zoom in for a closer look.

5 Click the Bookmarks menu and click Southeast.Among other problems , Myrtle Beach is in the ocean ; Grand Rapids , Michigan, is inIndiana ; Columbus, Ohio, is in Kentucky; and Nashville, Tennessee, is in Alabama.

G r a n d R a p ldsElkhar t

o 0 tf9^c.. W w YorkrdoDes Mones oYorkooC o l u m b u soo l n i r^ o.. Parkarsbura

, Charlottesville

Fortunately, you can use ArcToolhox to add the missing coordinare system information.Once you do that, ArcMap will be able to reproject the FastCities layer, and you'll seethe cities display in their correct locations.

Projecting data in ArcM i ' 365

6 On the Standa rd toolbar , c lick the Show/Hide ArcTo olbox Wind ow b ut ton.

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7 In the ArcToolbo x Window, c l ick the plus s ign next to Data Manageme nt Tools. C l ickthe p lus s ign next to Pr ojections and T ransformations.1 4 f$ Analysis Tools

C ar t o g r ap h y T o o l sC o n v e rs io n T o o lsD a t a M a n a g e m e n t T o o l s

D a t a C o m p e n s a n ^ Database

G lb Domainso t & Feature ClassiR FeaturesE7 lb FeldsO ko F i l e Geod atab aseE$1 General+ O l b G e n e r a l iz ationO IndexesE Joinso. Layers and Table Viewsp P rojections and Transforrr

E. FeatureE. Raster

ji Create Custom Geogrj% Define Projection+ Raster41 1 ! J

Pasantes Index Search ResuRs

8 Double -click the Define P rojection tool to ope n it .9 C l ick the Input Dataset or Featu re C lass drop-down ar row and cl ick FastC ities. lyr .

a D~ 1Proje WnInpc Dataset or Feature Classi FastCities.lyrC o o r d m a t e S y s t e m

Unknown

_ u XGi

OK Cancel Environments... S h o w l t e l e

You see that the layer' s coordinate system is Unknown.

366 Sectzolz 5: / l ualyzi fzg f 'a t i re re lrationsbip^

10 C l ick the P roper t ies bu t ton next to the C oord inate System b ox.

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5Rettel Rdercnee PraRafies

_xe J seectaoredef-d-~e:taa.Impon a coordiate system and X z a n d M

Lrpxt"' I dra aros H. an existinggmdatasetfeatue dataset, fearuedaaa, raster).Mew ' I Creare a new coordinare system.

Edt the popentiess of the currently safectedoto, tate system.

In the Spatial Referente Properties dialog box, you can select from coordinate systemsalready defined by ArcGIS, import a coordinate system from another dataset , or crearean entirely new coordinate system. (You might do Chis, for example , if you were mak-ing a map of a newly discovered planet, lince ArcGIS only has predefined coordinatesystems for planets in our solar system.)The Lamben conformal conic for North America, however, is defined by ArcGIS.

11 C l ick Select .12 In the Browse for C oord inate System d ialog bo x, dou ble-cl ick the Pr ojected C oord inateSystems folder , the C ont inental folder , and the North Amer ica folder . C l ick NorthAmer ica Lamber t C onforma) C on ic.p r j. (You may need to widen the Name header tosee the fu l l project ion nam es.) Make cure that your d ialog box m atches the fol lowinggraphic, then cl ick Add .

Projecting data in Arc11' ti 1 367

B r e w o e r a r [ o c n l 1 e s m e m x

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Look ro J NorthAmerica : - ] j^JNAD 1963 Great Lekes Bas in Albers . prj Coordnate System

^'North Amer ica Albers Equa l A tea Conk.prjtNor th Amer ica Equ chstan t Conlc.pr jj? a la th A e a Lamber t =onhx eral Cer^i

Coordnate SystemCoordinate SystemCoordnate System

US National Atlas Equal Area . prj Coordnate SystemOUSA Contiguous Abers Equal Area Corec . p r j C o o rd in a t e S y s t e m.yi USA Cont iguoUS Abers Equa l Area Conlc U... Coordna te 5ys temFUSA Corltiguous Egodistant Coree.prj Coordlnate 5ystemFU SA Con t i guous Lambert Conforma ) Conic.prj Coordna te Sys tem

N a r r eShow o l type

North Amel ica Lambert Cordormal Con lc p r iCocenete Systeens

fo o

A d dCancel

The Spatial Reference Properties dialog box is updated with the coordinate system details.

) t COOrdlaate 5ystem 12 C o a r re ce Sy s t e mN e n e : North Nraire ldrbert Cmformal CaricD eta l l :

P r oj ec t 'w n : L a m b e r t C r A t e r r i C O M eFalse_Eerrrn9: n000000Fa l l e North : D . OW W OCentral Mandan: - 96.000000St a n d a rd _Paral lel _ 1: 20.000000S >

The coordinate system information will be written to a projection file (.prj) associatedwith the FastCities shapefile.

368 Section 5: ,4nalyzing featnre re la tioris l l ip . s

14 C lick OK.

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The Define Projection tool runs and you see a progress report.15 C l ick Close on the progress repor t . C lose the ArcToolbox window.

*Des Moins Blomingtoni C o l u m u sBaltnor ! ver

Park burga OCharlott, sville

With the correct coordinate system information, ArcMap reprojects the FastCities layerfinto the Albers equal anea conic projection. The cities appear in their correct positions.16 From the Bookmarks m enu , c lick Lower 48 af ter Project ion.

You will copy the FastCities layer to the other two data frames.17 On the View menu, click Layout View.1 8 In t h e t a b l e o f contents, r ight-c lick FastC ities. lyr a nd cl ick C opy.

Projecting data in A rcMlrp 369

19 In the table of contents, r ight-click the Hawaii data frame and click Paste Layer(s).Again in the table of contents, r ight-click the Alaska data frame and click Pa ste Layer(s).

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Honolulu and Anchorage appear in their respective data frames.

E E ~6x&204207i 1006W~He9PG B 99 S .1 - + 1 21 793515

F O O O C e s . l 4 eP c t G r mvM. 01020201040

401084RdesP or0m0 0 ,0 ,06000, lol00020201067

f Fa#CBes.lyrPe0G00M. 00020 2000404000 84

f- ', Ra[ezP0010 Gow1A

COlo 10[01020200067

-J :jl o-ib Cl r R?

U.S. Popu lat ion Growth1 9 9 0 -9 0 . 1002 0 0 0

p,gyy souce sdeaim ^ J 21 e 0nR u - A,-I olAZ- ,aBLS A- - -d. -3.64 6.650n

In the Alaska data frame, the FastCities layer is reprojected to Alaska Albers equal areaconic. In the Hawaii data frame, it is reprojected to Hawaii Albers equal area conic.Your map shows which states and cities have experienced the most growth between1990 and 2000.

20 If you want to sav e you r work, save i t as my_exl3b.mxd in the \GTKA rcGIS \C ha pte r l3\M yData folder.In the next chapter, you will work exclusively with ArcCatalog, so you'll exit ArcMap now.

21 Close ArcMap. C l ick No if prompted to sav e your changes.

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