QGIS training class 1

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Geographic Information SystemQGIS Introduction(1)

microbase.LLChttp://microgeodata.com/

http://microgeodata.com/

http://microgeodata.com/


Agenda

1st

2nd

3rd

W h a t ’s Q G I S ? B a s i c u s a g e B a s i c d a t a m a n a g e m e n t

S p a t i a l d a t a h a n d l i n g S p a t i a l A n a l y s i s

G e o c o rd i n g C re a t e Ve c t o r d a t a A b o u t c o o rd i n a t e s y s t e m C re a t e K M L d a t a U t i l i z e O S M d a t a


Contents Today

1st session

1 What’s QGIS?

2 Basic usage

3 Basic data management

4 Map design

Homework


What’s Quantum GIS (QGIS)?

• One of open source GIS software named FOSS4G (Free and Open Source Software for Geospatial)

• a user friendly GUI

• Multi-platform（Win, Mac OS X, Linux）

• Multi-language

• Rich functions for a function enhancement


What QGIS can do?

Create and edit GIS data

Display GIS data

(overlay, thematic map...)

Select / Join data GIS data analysis


Bas ic usage


2.1 Launch QGIS

• Double click the QGIS shortcut icon on desktop

• The window will open.


QGIS window will open like below.


toolbar menu

map viewLayer

map info / settings

topmenu


Ins ta l l P lug in

• Choose “Fetch Python Plugins...” from “Plugins” on the top menu and search “Table Manager” from Filter form in “Plugins” tab.

• “Table Manager” is a database management tool.

• Choose and install “Table Manager”.

• When installing plugin, internet environment is necessary.


• Choose “Manage Plugins...” from “Plugins” on the top menu and click the “Add Delimited Text Layer”.• “Add Delimited Text Layer” function is used for importing CSV format data.

• Checked function will be visible on the main menu and able to be used.

“Add Delimited Text Layer” will be visible.

Plugin Management


2.2 Add data

GIS data can be devided into 2 types..

• Raster type　　ex) JPEG, PNG, TIFF

• Vector type　 ex) Shape file(.shp)

For instance, imagine a river and bridge,

Raster typeaggregate of colored dots

Vector typeline data connecting starting points and end points


Exercise data

lecture1_data

tokyo23

homework1


About Shape f i le

• Vector type data mostly used in the world.

• Available in most GIS softwares.

• “Shape file” format is composed of more than 3 files as follows.

*.shp (geometry type and geographical coordinates)

*.dbf (attributes of features such as name and figure)

*.shx (relationship between shp and dbf)

*.prj (the coordinate system and projection info)

Shape file

same file name

These files must be put in same folder.


NAME AREA PERIMETER

0

1

2

3

4

5

AAA 18352 644

BBB 22496 756

CCC 22050 602

DDD 7548 352

EEE NA NA

FFF NA NA

*.shp *.dbf *.shx

CCC

AAA

DDD

BBB

Point Data ex) amedas data, shop data

Line Data ex) road data, railway data, river data

Polygon Data ex) city shape, building data

<Feature type>


1) Click “Add vector layer”

2) Browse file

3) Open

Add “ku.shp” in “tokyo23” folder.


※ Caut ion ※

• Japanese GIS data by Government such as National Land Numerical Information and census data tend to be recorded in Shift-JIS. If you use Mac OS or Unix, Check that the encoding is Shift-JIS before adding the data.

• Shift-JIS can be converted to UTF-8 later.


Tokyo special districts are displayed.


Disp lay a feature

1) Click “Identify Feature”

2) Click a feature


Shibuya info can be shown in a new window.


1) Click “Save Project”　(Ctrl + S or Command + S） 2) You can save it any name in any folder.

3) save a project as “.qgs” type

2 .3 Save a pro ject


Exerc ise1

Add following data in the folder “tokyo23”.

subway.shp (Line data: a subway in Tokyo Special district)

station.shp (Point data: a station in Tokyo Special district)

convenience.shp (Point data: a convenience store in Tokyo Special district)

elevation.shp　(Polygon data: an terrain data in Tokyo special

district)


Hint

You can select plural files while pushing Ctrl key ( or Command key).


Answer


The order of layer on TOC can be altered by drag and drop.

Front

Back

2.4 Change an order of each layer


A layer can be h idden without check ing a check box of layer.

Only subway and station layer can be seen on map view.


Delete a layer

Delete other than “ku” layer.

# This function doesn’t delete a file itself in the file directories.


Bas ic data management


What ’s an “at t r ibute”?

NAME AREA PERIMETER

0

1

2

3

4

5

A棟 18352 644

B棟 22496 756

中庭 22050 602

生協購買 7548 352

ポスト NA NA

道路 NA NA

中庭

A棟生協購買

B棟

・ポスト

attribute table

“Attribute” means an property of each feature such as a name and an area. In case a shape file is used, the attribute is saved into a dbf file and can be edited.

The feature “0” has a name of “A building” and an area of 18,352 square meters, perimeter of 644 meters.


Open Attr ibute table

See an attribute table of “ku” layer.

• Add “ku.shp” on layer and open its attribute table.

field

Each line links to vecoter on map.

Click “ku” layer on the right mouse and choose “Open Attribute Table”.


If you choose a line from attributes, the linked map feature also be chosen.

If you choose a map feature on map view, the linked line also be chosen in the similar way.

click a line number which you’d like to choose.

Choose “Select Single Feature” and click a map feature on map view.


Se lect layer by at t r ibute

Select a city which has more than 20 km2 in area from attribute table.

About fields

• KU : city id

• NAME : city name

• PERIMETER [ m]

• AREA [m2]

1) Click “Advanced Search”.


Input a condition expression on “SQL where clause”.

If you click, item will be added to “SQL where clause”.

“Test” show you whether the condition expression is correct or not, and the number of matched features

Input “AREA >= 20,000,000”( m2 -> km2 )


12 cities are selected.

Deselect


Se lect features under p lur a l condi t ions

AND and OR enable to se lect features under p lur a l condi t ions .

case1 : ku which has more than 10 km2 and less than 20km2 in area

AREA >= 10000000 AND AREA < 20000000

AREA < 10000000 OR AREA >= 20000000

Also, NOT i s use fu l when you ’d l i ke to se lect features under

oppos i te condi t ions .

case3 : ku which doesn ’ t have not less than 20km2

NOT AREA < 20000000

case2 : ku which has less than 10 km2 or more than 20 km2


Exerc ise 2

1) Select city features which has more than 50km in “PERIMETER” and doesn’t have less than 50km2 in “AREA”

2) Save the selected features as “large_wards.shp” in “tokyo23” folder.

3) Open “large_wards.shp” in QGIS


Answer

PERIMETER >= 50000 AND NOT AREA < 50000000


Jo in table

“Join table” is to combine different table based on a key field in common.

This function is very useful when you combine GIS data with others or external data such as csv and dbf data.

NAME AREA

0

1

2

Hokkaido 83456.38

Aomori 8918.45

Iwate 15278.85

PREF POP

0

1

2

Hokkaido 5506419

Aomori 1373339

Iwate 1330147

NAME AREA PREF POP

0

1

2

Hokkaido 83456.38 Hokkaido 5506419

Aomori 8918.45 Aomori 1373339

Iwate 15278.85 Iwate 1330147

name, area name,population

add pop field into the target table based on the prefecture name.


The column “pop” has population data in Tokyo in 2010.

Load “ku_pop.csv” in “tokyo23” into QGIS.

“Layer” > “add vector” > import csv


CSV data has been added.


Join population data in Tokyo special districts into “ku” layer.

Choose a “join” tab above menu of the layer property “ku” layer

csv layer

Use city name as a key field

shp csv


You can join / unjoin other data more.

“ku_pop” layer is joined to “ku” layer.


“ku_pop” at t r ibutes has been jo ined .

Attributes of “ku” Attributes of “ku_pop”


Decide where one wants to save the files.

Save the joined layer as “ku_pop.shp” in “tokyo23”.


Open “ku_pop.shp” and check that the attribute table is joined one or not.


Calcu late f ie ld

“Calculate field” enable to handle field values at once.

Calculate a population density in each area using “pop” and “AREA” fields in the attribute of “ku”.

Population density = Population / Area [pop / km2]


Togg le ed i t mode

Toggle edit mode before calculate field.


Click “calculate field”.

Ca lcu late f ie ld

“pop” field is loaded as string. the field in CSV are all regarded as string.

Caution:“calculate field can’t be conducted when string and figure data coexist together.


to int ( ) = ( ) 内のフィールド値を整数に変換

Fill as above


Jo ined ! !


Map Des ign


Exerc ise1

Add following data in the folder “tokyo23”.

subway.shp (Line data: a subway in Tokyo Special district)

station.shp (Point data: a station in Tokyo Special district)

convenience.shp (Point data: a convenience store in Tokyo Special district)

elevation.shp　(Polygon data: an terrain data in Tokyo special

district)

Again


Change point s ty les

Click “Property” on the right mouse button station(or double click the layer).


Open the window “ layer proper ty” and choose “sty le” tab.


“Symbol proper t ies” window wi l l open .

1) Change symbol layer type to “SVG mar ker”

2) Choose a mar k of “ t r a in” f rom the image l i s t .


The stat ion symbol has changed .


Uncheck the check box other than “elevation” layer and open its properties(or double click the layer).

Change polygon sty les


Change a co lor of “e levat ion layer” accord ing to e levat ion va lue .

Low High

Genera l ly, h igher area co lor s warm color(ex . red ,ye l low) . Lower area co lor s co ld co lor(ex . blue ,green) .


1) Choose “Graduated”. 2) Choose a column “ELEV” which has elevation value.

3) Choose any color ramp. An original color ramp can be made.

4) Choose a number of classed and a classification mode.

5) Finally, click “Classify”. Then the classification result will be displayed above.

If you’d like to arrange your way, just click “Symbol color”, “Range” and “Label”.


Resu l t


Change par t ia l symbol s ty les

show different markers depending on attributes.


1) Choose “Graduated”.

2) Choose and double click a rule row which you’d like to change. Then the rule property will open.(Default setting has no rule)


4) Input “CNAME LIKE ‘Circle%’ on “Expression” form. (or “CNAME = “circleK”)

‘LIKE’ : partial matching‘=‘ : perfect matching

3)Input any name in “Label” form. Click “...” next to “Filter” form.

5) Marker type can be chosen as mentioned before.

A filter rule can be input from “Expression string builder”.


Existing rule has been edited.

If you’d like to add an another rule or delete


Only “Circ leK” has been d isp layed .


Disp lay a labe l

1) Choose “Label” tab from tab menu in Properties “ku”

2) check the checkbox of “Display labels”.

3) Choose “NAME” in “Field containing label” form.


The name of “ku” has been d isp layed as a labe l on the polygon data .


Exerc ise 2

1) Delete the label “ku”.

2) Add pop.shp(population on street scale).

3) Classify poplation in 1995(“P1995”) into 4 categories as follows.

class 1 : 0 ～ 1000 (blue)

class 2 : 1001 ～ 2500 (green)

class 3 : 2501 ～ 5000 (yellow)

class 4 : 5001 ～ (red)


Hint


Answer


Map Expor t

Export your map an imagery file for printing. QGIS has an additional function such as adding a direction symbol and a scale bar for printing.

Click “New print composer” icon from toolbars.

Add a map, symbols and others to Initial screen from the menu.


1) Click “Add new map” icon

Add a map into composer screen

2) Drag at any place on the composer screen while choosing “Add new map” icon

map size and other settings can be adjusted freely.


Those elements can be modified from “Item Properties” at the right side

Add icon and pictures.

Add Label

Add legend

Export as an imagery, PDF, SVG.


Contents Today

1st session

1 What’s QGIS?

2 Basic usage

3 Basic data management

4 Map Design


HOMEWORK


DATA

homework1

pref_pop.csv

Japan_pref.shp


(1) Add “Japan_pref.shp” and “pref_pop.csv” on layer.

(2) Join “Japan_pref” layer with “pref_pop” and save it as “Japan_pref_new.shp”.

(3) Calculate population density in all prefecture using both “pop2010” and “pop2035” field.

(4) Classify the poplation density in 2010 and 2035 into 5 categories.

Education

QGIS training class 1