Using PostGIS To Add Some Spatial Flavor To Your Application

Using PostGIS to add some spatial flavor to your applications Steven Citron-Pousty Developer Evangelist deCarta

Agenda ,[object Object],[object Object],[object Object],[object Object],[object Object]

Assumptions about you ,[object Object],[object Object],[object Object],[object Object],[object Object]

What is PostGIS ,[object Object],[object Object],[object Object]

Competitive Offerings ,[object Object],[object Object],[object Object],[object Object],[object Object]

Installing ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Other Steps ,[object Object],[object Object],[object Object]

Two more things you need to understand Almost there – I promise

Shapefiles when is a file not a file

More Projection Goodness ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Projecting using ogr2ogr ,[object Object],[object Object],[object Object]

Now let’s make some SQL ,[object Object],[object Object],[object Object]

Y’all know what to do with SQL ,[object Object],[object Object]

Let’s get this party started ,[object Object],[object Object],[object Object],WTF!

Well Known Text (WKT) ,[object Object],[object Object],[object Object],[object Object]

Lesson Learned ,[object Object],[object Object],[object Object],SELECT asKML(the_geom) FROM watercourses WHERE gid = 17;

Inserting a new record ,[object Object],INSERT INTO firestations(station_na, the_geom) VALUES('Best LittleFire House in CA', ST_SetSRID(ST_MakePoint(-119.5, 34.5), 4326) );

Distance ,[object Object],SELECT gid FROM waterbodies WHERE ST_DWithin('SRID=4326;POINT (-119.103762382096 35.4122898449297)', the_geom, 0.005); gid ----- 4 5 6 7 8

Let’s find all the parcels in Agricultural Zones SELECT p.gid FROM parcels AS p, zoning AS z WHERE z.comb_zn LIKE 'A%' AND ST_Within(p.the_geom, z.the_geom);

Do something with the geometry after selection

Calculating Area SELECT sum(ST_Area(z.the_geom)) FROM zoning AS z WHERE z.comb_zn LIKE 'NR%'; sum -------------------- 0.0131834159551545

Turn polygons into points SELECT gid, asText(ST_Centroid(the_geom)) FROM waterbodies WHERE gid = 124; gid | geometry -----+------------------------------------------- 124 | POINT(-118.427120958287 35.6702299014044) SELECT gid, asText(ST_PointOnSurface(the_geom)) FROM waterbodies WHERE gid = 124; gid | geometry -----+------------------------------------------- 124 | POINT(-118.449967685908 35.6911672413056)

Create new tables using a select CREATE TABLE biglake WITH OIDS AS SELECT gid, the_geom FROM waterbodies WHERE gid = 124; SELECT ST_AREA(the_geom) FROM biglake; st_area --------------------- 0.00313986591299908

Some SQL to buffer SELECT ST_Area(ST_Buffer(the_geom, 0.1)) FROM biglake; st_area -------------------- 0.0718529848413709 Remember that is used to be 0.003

Clip to the bounding box SELECT gid, ST_Intersection(the_geom, 'SRID=4326;MULTIPOLYGON((( -119.5 35.0, -119.0 35.0, -119.0 35.5, -119.5 35.5, -119.5 35.0)))') FROM watercourses WHERE ST_Intersects(the_geom, 'SRID=4326;MULTIPOLYGON((( -119.5 35.0, -119.0 35.0, -119.0 35.5, -119.5 35.5, -119.5 35.0)))');

Simplifying geometries ,[object Object],[object Object],[object Object]

Select ST_NPoints(the_geom) FROM watercourses WHERE gid IN (12, 14, 17); st_npoints ------------ 265 68 48

SELECT ST_NPoints(ST_Simplify(the_geom, 0.00001)) FROM watercourses WHERE gid IN (12, 14, 17); st_npoints ------------ 65 19 18

SELECT ST_NPoints(ST_Simplify(the_geom, 0.0001)) FROM watercourses WHERE gid IN (12, 14, 17); st_npoints ------------ 18 6 7

So how do you bring this together in an app ,[object Object],[object Object],[object Object]

Where do you go now - PostGIS ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Where to get Data ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Map API to use ,[object Object],[object Object],[object Object],[object Object]

Using PostGIS To Add Some Spatial Flavor To Your Application

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Using PostGIS To Add Some Spatial Flavor To Your Application

Ähnlich wie Using PostGIS To Add Some Spatial Flavor To Your Application (20)

Mehr von Steven Pousty

Mehr von Steven Pousty (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Using PostGIS To Add Some Spatial Flavor To Your Application