Paul Ramsey

Build your own MapQuest!

Adding Spatial Smarts to PostgreSQL with PostGIS

Paul RamseyRefractions Research

Paul Ramsey

http://mq-mapgend.websys.aol.com:80/mqmapgend?MQMapGenRequest=FDR2dmwjDE%3byt29%26FDJnci4Jkqj%2cMMCJ%3aHOEvq%3bwy5lab%3a%29uaxlw1w%26%40%24%3a%26%40%24s%26wzx%26a8x%26ESEKGF%3dTPWIK%2crgqabx%26%3d2llarwh%40%24%3a%26%40%24%3a%26a2%3a

Paul Ramsey

On-the-Fly Cartography

GIS DataCartography

EngineColorfulPicture

Paul Ramsey

GIS Data

• File Formats

• Data Organization

• Coordinate Projections

• Data Access

• Data Quality

Don’t Panic

Paul Ramsey

File Formats

• At least one per vendor– ESRI : Shape, Coverage, E00, GeoDatabase– CAD : DXF, DGN– Government : SDTS, TIGER, DLG– MapInfo : MIF/MID, TAB– Standards : GML

• Open source conversion– OGR (gdal.maptools.org/ogr)

Paul Ramsey

Data Organization

• By Administrative Unit– Counties, States

• By Gridding Unit– USGS 24K Quads, NTS Mapsheets

• By Natural Unit– Watersheds

Paul Ramsey

Coordinate Projections

1859612,511175-114.068,49.000

GeographicLongitude / Latitude

Albers Equal AreaOrigin -126,0

Parallels 58.5,50.0Offsets 1000000,0

Paul Ramsey

Coordinate Projections

• United States– UTM (Universal Transverse Mercator)– “Stateplane”

• Lambert• Transverse Mercator

– Geographic

• Always Find Out the Projection of Your Data– .prj file

Paul Ramsey

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Data Access

• United States– Mostly Free Federal Data

• www.geodata.gov• tiger.census.gov• www.fgdc.gov• transtats.bts.gov• geonames.usgs.gov• www.fws.gov/data

– Some Free State Data– Little Free County / Municipal Data

Paul Ramsey

Data Acce$$

• Commercial Providers– NavTeq– TeleAtlas ( + GDT )– MapInfo– DigitalGlobe– SpaceImaging

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QuickTime™ and aTIFF (Uncompressed) decompressor

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QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Paul Ramsey

Data QualityUSGS DLG TIGER Census

Paul Ramsey

Cartography Engine

ProprietaryArcIMSMapExtreme

Open SourceGeoServerDeeGreeUMN Mapserver

Paul Ramsey

UMN Mapserver

• mapserver.gis.umn.edu• Multiple Format Support

– Shape, TAB, Coverage, DGN, PostGIS, More…

• Multiple Projection Support• Standards Support

– OpenGIS Web Map Server– OpenGIS Web Feature Server– OpenGIS Styled Layer Descriptor

Paul Ramsey

UMN Mapserver

Format AProjection 1

Format BProjection 1

Format CProjection 2 “Map File”

ourmap.map

Mapserver

Paul Ramsey

MAP EXTENT 1192130 379840 1199560 385520 SIZE 400 400 SHAPEPATH "/Users/pramsey/Sites" PROJECTION "init=epsg:42102" # BC Albers END LAYER NAME "Lakes" STATUS ON DATA "lakes" TYPE POLYGON PROJECTION "init=epsg:42102" # Geographic END CLASS NAME "Lakes" COLOR 205 223 255 END ENDEND

Paul Ramsey

UMN Mapserver & PostGIS

PostGIS / PostgreSQL

SpatialDatabase

“Map File”

ourmap.map

Mapserver

Paul Ramsey

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This is your Database…

• “Is there a Main Street?”• “How many patients does the prenatal

center serve?”• “How many buildings in the city have

more than two stories?” • “What is the total amount of cash

withdrawals for customer X?”

Paul Ramsey

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This is your Database on Spatial…

• “What is the total length of Main Street?”

• “What is the total number of patients within 3 miles of the prenatal center?”

• “How many buildings of more than 2 stories are along the parade route?”

• “Have all the cash withdrawals for customer X been within 50 miles of her primary residence?”

Paul Ramsey

PostGIS / PostgreSQL

• Extension to PostgreSQL– src/contrib/

• GEOMETRY– Point, Line, Polygon, Multi*– Functions– Indexes

• http://postgis.refractions.net

Paul Ramsey

PostGIS Types

• POINT• LINESTRING• POLYGON• MULTIPOINT• MULTILINESTRING• MULTIPOLYGON• GEOMETRYCOLLECTION

.

..

Paul Ramsey

PostGIS Types

id | geometry | name ------+---------------------------+-------------- 1294 | POINT(1199437.8 382509.2) | Brighton Ave 1295 | POINT(1199369.3 382741.7) | York Pl 1296 | POINT(1199494.8 382751) | Prospect Pl

Paul Ramsey

PostGIS Functions

• Single Geometry– Float : Length(Geometry)– Float : Area(Geometry)– Integer : NumGeometries(Geometry)– Integer : NumPoints(Geometry)– Geometry : Buffer(Geometry,Float)– Point : PointN(Geometry)– Text : AsText(Geometry)– ByteA : AsBinary(Geometry)

Paul Ramsey

PostGIS Functions

• Multiple Geometry– Float : Distance(Geometry,Geometry)– Boolean : Touches(Geometry,Geometry)– Boolean : Intersects(Geometry,Geometry)– Boolean : Disjoint(Geometry,Geometry)– Geometry : Intersection(Geometry,Geometry)– Geometry : GeomUnion(Geometry,Geometry)– Geometry : Difference(Geometry,Geometry)

Paul Ramsey

PostGIS Indexes

• Geometries Require Special Index– Sortable in two dimensions– Cover range of values

• R-Tree Index (GiST Implementation)• Linear Time Picksplit Algorithm• http://postgis.refractions.net/rtree.pdf

Paul Ramsey

Paul Ramsey

Paul Ramsey

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Get on with it!!Get on with it!!

Paul Ramsey

Our Architecture

PostGIS / PostgreSQL

SpatialDatabase

Map File

ourmap.map

Mapserver

GIS Data

Paul Ramsey

Our Steps

1. Install / Setup• Mapserver, PostGIS• GDAL, OGR, PROJ4, GD

2. Acquire GIS Data3. Load GIS Data PostGIS4. Write Map File for Mapserver5. …6. Profit!

Paul Ramsey

Acquire Data

• For demo, hunted down Oregon data:

1981636 Jul 28 12:02 OR_deci.zip 564501 Jul 28 11:55 county.zip34729355 Jan 9 2003 hydrogm020.tar.gz62246216 Jul 28 11:55 gdt.zip 1853534 Jul 28 11:55 railroads.zip 3293501 Jul 28 12:42 s_12my03.zip

Paul Ramsey

Load Data

• Load names data with perl script:

"OR","4H Camp","locale","Coos",41,011,"431355N","1235945W",43.23194,-123.99583,"","",,,216,,"","Dora"

INSERT INTO names VALUES

(1,'OR','4H Camp','locale','Coos','SRID=4269;POINT(-123.99583 43.23194)',216,NULL,'Dora’

);

Paul Ramsey

Load Shape Files

• PostGIS includes Shape loader utility:

shp2pgsql -s 200000 \counties.shp counties | psql demo-oregon

Paul Ramsey

Write Map File

• Good computer cartography is the artful combination of elements, styles, colors and data at appropriate scales.

• MapQuest is an example of excellent cartography.

• So is a National Geographic Atlas of the World.

Paul Ramsey

LAYER TEMPLATE template.html DUMP TRUE NAME "States" METADATA "wms_title" "States" END STATUS ON DATA "the_geom from states" TYPE POLYGON CONNECTIONTYPE POSTGIS CONNECTION "user=pramsey dbname=demo-oregon" PROJECTION "init=epsg:4269" END CLASSITEM "admin_name" CLASS NAME "States" COLOR 255 255 230 OUTLINECOLOR 20 20 20 EXPRESSION "Oregon" END CLASS NAME "States" COLOR 240 240 240 OUTLINECOLOR 20 20 20 END END

Paul Ramsey

Paul Ramsey

Demonstration

• iBook G3 800Mhz 128MB– PostGIS / PostgreSQL, Mapserver, Apache

• Roads• States• Counties• Geographical Names• Water Features