Introduction to post_gis

Intro to PostGis

For beginners

Alban de Lavenne

17 décembre 2012

How do you organise your data ?

The problem :

lots of di�erent �les, formats : csv, txt, xls, shp, asc ...

in di�erent folders more or less well organised and easy to �nd

lack of descriptions (source, stations, projection, last version ...)

reproducible science ?

easy sharing ?

easy backup ?

Do you need a database ?

not so di�cult to built

enforce you to organize you data

save you a lot of time in the long run

A. de Lavenne (INRA, Rennes) University of Trento 17 décembre 2012 2 / 25


The problem :





easy sharing ?

easy backup ?







The problem :





easy sharing ?

easy backup ?







The problem :





easy sharing ?

easy backup ?







The problem :





easy sharing ?

easy backup ?







The problem :





easy sharing ?

easy backup ?







The problem :





easy sharing ?

easy backup ?






What Is PostGIS ?

Open source object-relational database management system (ORDBMS)Widely considered as the most full-featured open-source database system.

PostGIS = database extender for the PostgreSQL Database Management System

open source, freely available, fairly OGC compliant

In a nutshell it adds spatial functions such as :

distance, area, union, intersection

specialty geometry data types to the database


Installing PostgreSQL with PostGIS Functionality

Install PostgreSQL �rst, then PostGIS extension (using Stack Builder)http://www.postgresql.org/download/

http://postgis.refractions.net/download/

Windows

http://www.postgresql.org/download/windows

Mac

http://www.kyngchaos.com/software:postgres

Ubuntu

sudo apt-get install postgresql postgis

psql -d template1 -c "alter user postgres with password 'postgres'"


http://www.postgresql.org/download/

http://postgis.refractions.net/download/

http://www.postgresql.org/download/windows

http://www.kyngchaos.com/software:postgres

Creating a database

Using pgAdminIII interface

Right clic on database

or using SQL query

CREATE DATABASE blavetWITH ENCODING='UTF8'

OWNER=postgresLC_COLLATE='fr_FR.UTF -8'LC_CTYPE='fr_FR.UTF -8'CONNECTION LIMIT=−1;


Adding spatial extension

Using pgAdminIII interface

Right clic on extensions

or using SQL query

CREATE EXTENSION postgisVERSION "2.0.1"

Check the table "spatial_ref_sys"Check also that you have lots of new functions


Organising a database

How would you organise a database ? Having :

Runo� time series of di�erent basins

Rainfall time series of di�erent raingauges

Spatial description of those measurements

Other spatial informations (like soil type, geology...)


Adding tables

Table of basins

CREATE TABLE basins(

id_basin serial NOT NULL ,name text ,city text ,altitude numeric ,area numeric ,x_lambert2e numeric ,y_lambert2e numeric ,CONSTRAINT basins_pkey PRIMARY KEY ( id_basin )

)WITH (

OIDS=TRUE) ;ALTER TABLE basins

OWNER TO postgres ;


Adding tables

Table of measures of runo�

CREATE TABLE measures_runoff(

id_runoff serial NOT NULL ,id_basin integer NOT NULL ,datehourmeasure timestamp with time zone NOT NULL ,runoff numeric ,timestep text ,unit text ,source text ,CONSTRAINT measures_runoff_pkey PRIMARY KEY ( id_runoff ,

id_basin , datehourmeasure ))WITH (

OIDS=FALSE) ;ALTER TABLE measures_runoff

OWNER TO postgres ;


Adding tables

Table of raingauges

CREATE TABLE raingauges(

id_raingauge serial ,id_meteofrance integer ,city text ,name_raingauge text ,altitude numeric ,type_raingauge text ,producer text ,latitude_dec numeric ,longitude_dec numeric ,CONSTRAINT raingauge_pkey PRIMARY KEY ( id_raingauge )

)WITH (

OIDS=TRUE) ;ALTER TABLE raingauges

OWNER TO postgres ;


Adding tables

Table of measures of rainfall

CREATE TABLE measures_rainfall(

id_rainfall serial ,id_raingauge integer ,datehourmeasure timestamp with time zone ,rainfall numeric ,timestep text ,unit text ,CONSTRAINT rainfall_pkey PRIMARY KEY ( id_rainfall ,

id_raingauge , datehourmeasure ))WITH (

OIDS=FALSE) ;ALTER TABLE measures_rainfall

OWNER TO postgres ;


Adding tables

Table of antilope points

CREATE TABLE antilope_points(

id_point numeric NOT NULL ,x_lambert2e numeric ,y_lambert2e numeric ,CONSTRAINT antilope_points_pkey PRIMARY KEY ( id_point )

)WITH (

OIDS=TRUE) ;ALTER TABLE antilope_points

OWNER TO postgres ;


Adding tables

Table of measures of antilope points

CREATE TABLE measures_rainfall_antilope(

id_measure serial ,id_point integer ,datehourmeasure timestamp with time zone ,rainfall numeric ,units text ,CONSTRAINT measures_rainfall_antilope_pkey PRIMARY KEY (

id_measure ))WITH (

OIDS=FALSE) ;ALTER TABLE measures_rainfall_antilope

OWNER TO postgres ;


Filling tables

Import �les to database

COPY basins ( id_basin , name , city , altitude , x_lambert2e , y_lambert2e )FROM '.../ Intro_to_PostGIS/basins.csv' with delimiter ';' ;

COPY measures_runoff ( id_basin , datehourmeasure , runoff , timestep ,unit ) FROM '.../ Intro_to_PostGIS/runoff.csv' with delimiter ';' ;

COPY raingauges ( id_raingauge , id_meteofrance , city , name_raingauge ,altitude , latitude_dms , longitude_dms , type_raingauge , producer ,latitude_dec , longitude_dec ) FROM '.../ Intro_to_PostGIS/raingauges.csv' with delimiter ';' ;

COPY measures_rainfall ( id_raingauge , datehourmeasure , rainfall ,timestep , unit ) FROM '.../ Intro_to_PostGIS/rainfall.csv' withdelimiter ';' ;

COPY antilope_points ( id_point , x_lambert2e , y_lambert2e ) FROM '.../Intro_to_PostGIS/antilope_points.csv' with delimiter ';' ;

COPY measures_rainfall_antilope ( id_point , datehourmeasure , rainfall, units ) FROM '.../ Intro_to_PostGIS/antilope_rainfall.csv'with delimiter ';' ;


Adding internal spatial information

AddGeometryColumn

AddGeometryColumn ( schema_name , table_name , column_name , srid ,type , dimension )

(Source : JUMP, Technical Report)



(Source : OpenGIS Simple Features Speci�cation for SQL)


Geometry Constructors and Geometry Accessors

ST_MakePoint

ST_MakePoint ( x , y , z )

Full list here : Geometry Constructors

ST_X, ST_Y and ST_Z

ST_X ( geometry )ST_Y ( geometry )ST_Z ( geometry )

Full list here : Geometry Accessors


http://www.postgis.org/docs/reference.html#Geometry_Constructors

http://www.postgis.org/docs/reference.html#Geometry_Accessors

Geometry Editors

ST_SetSRID

ST_SetSRID ( geom , srid )

ST_Transform

ST_Transform ( geom , srid )

Full list here : Geometry Editors

A Spatial Reference System Identi�er (SRID) is a unique value used to unambiguouslyidentify projected, unprojected, and local spatial coordinate system de�nitions.

Large database of SRID created by the European Petroleum Survey Group (EPSG) iswidely used.


http://www.postgis.org/docs/reference.html#Geometry_Editors

Spatial Relationships and Measurements

Spatial Relationships and Measurements

ST_Area ( geometry )ST_Centroid ( geometry )ST_Contains ( geometry , geometry )ST_Distance ( geometry , geometry )

Full list here : Spatial Relationships and Measurements

Geometry Processing

ST_Buffer ( geometry , radius_of_buffer )ST_Union ( geometry set g1field )ST_Union ( geometry , geometry )ST_Intersection ( geometry , geometry )

Full list here : Geometry Processing


http://www.postgis.org/docs/reference.html#Spatial_Relationships_Measurements

http://www.postgis.org/docs/reference.html#Geometry_Processing


Adding geometry columns

−−Adding geometry columnsSELECT AddGeometryColumn ( 'basins ' , 'outlet_lambert2e ' , 27572 , '

POINT' , 2 ) ;SELECT AddGeometryColumn ( 'basins ' , 'outlet_lambert93 ' , 2154 , '

POINT' , 2 ) ;SELECT AddGeometryColumn ( 'basins ' , 'limits_lambert2e ' , 27572 , '

POLYGON ' , 2 ) ;SELECT AddGeometryColumn ( 'basins ' , 'limits_lambert93 ' , 2154 , '

POLYGON ' , 2 ) ;SELECT AddGeometryColumn ( 'raingauges ' , 'raingauges_lambert2e ' ,

27572 , 'POINT' , 2 ) ;SELECT AddGeometryColumn ( 'raingauges ' , 'raingauges_lambert93 ' ,

2154 , 'POINT' , 2 ) ;SELECT AddGeometryColumn ( 'antilope_points ' , '

antilope_points_lambert2e ' , 27572 , 'POINT' , 2 ) ;SELECT AddGeometryColumn ( 'antilope_points ' , '

antilope_points_lambert93 ' , 2154 , 'POINT' , 2 ) ;



Filling geometry columns

−−F i l l geometry columnsUPDATE basins SET outlet_lambert2e=st_setsrid ( st_makepoint (

x_lambert2e , y_lambert2e ) , 27572) ;UPDATE basins SET outlet_lambert93=st_transform ( outlet_lambert2e

, 2154 ) ;UPDATE raingauges SET raingauges_lambert2e=st_transform (

st_setsrid ( st_makepoint ( longitude_dec , latitude_dec ) , 4326),27572) ;

UPDATE raingauges SET raingauges_lambert93=st_transform (st_setsrid ( st_makepoint ( longitude_dec , latitude_dec ) , 4326),2154) ;

UPDATE antilope_points SET antilope_points_lambert2e=st_setsrid (st_makepoint ( x_lambert2e , y_lambert2e ) , 27572) ;

UPDATE antilope_points SET antilope_points_lambert93=st_transform( st_setsrid ( st_makepoint ( x_lambert2e , y_lambert2e ) , 27572),2154) ;


Adding external spatial information

Using graphical interface

Using Quantum-GIS extension (like QGIS spit)pgShapeLoader...

Using command line with shp2pgsql

shp2pgsql -iIDd -s 2154 -W utf8 basins_lambert93.shp basins_polygon > import.sql

psql -U postgres -W -h localhost -p 5432 -d blavet -f import.sql

OR

shp2pgsql -iIDd -s 2154 -W utf8 basins_lambert93.shp basins_polygon |

psql -U postgres -W -h localhost -p 5432 -d blavet

Filling geometry columns

UPDATE basins SET limits_lambert93=st_geometryn ( geom , 1 )FROM basins_polygonWHERE basins_polygon . id_basin=basins . id_basin ;

and limits_lambert2e ...


Exemple SQL of query

Select a chronique of runo�Calculate the area of one basinSelect raingauges inside one basinSelect average antilope rainfall time serie for each basinsImport shape�le geology and get a table of statistics of geology for each basinCheck if there is double measures in runo� and rainfall


Visualizing your data

Using Qgis to vizualize your dataPlugin in Qgis for query and shape�le creationPlugin in Qgis for importing data


Connect to your database with R


Connect to your database with R


Date post:	12-Apr-2017
Category:	Education
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Introduction to post_gis

Education