Database Reference
In-Depth Information
UAV photogrammetry in PostGIS - DSM
creation
Thephotogrammetryexamplewouldbeincompleteifwedidnotproduceadigitalter-
rainmodelfromourinputs.Afullyrigoroussolutionwheretheinputpointcloudwould
beclassifiedintogroundpoints,buildingpoints,andvegetationpointsisnotfeasible
here,butthisrecipewillprovidethebasicframeworkforaccomplishingsuchasolu-
tion.
In this recipe, we will create a 3D TIN, which will represent the surface of the point
cloud.
Getting ready
Before we start,
ST_DelaunayTriangles
is available only in PostGIS 2.1 using
GEOS3.4.Thisisoneofthefewrecipesinthisbooktorequiresuchadvancedver-
sions of PostGIS and GEOS.
How it works...
ST_DelaunayTriangles
will calculate a 3D TIN with the correct flag: geometry
ST_DelaunayTriangles
(geometry g1, float tolerance, int4 flags).
CREATE TABLE chp07.uas_tin AS
WITH tin AS
(
SELECT
ST_DelaunayTriangles(ST_Union(the_geom), 0.0, 2)
AS the_geom FROM
chp07.uas
)
SELECT the_geom FROM tin;
Now, we have a full TIN of a digital surface model at our disposal.
