Into the Nth Dimension - PostGIS - page 378

UAV photogrammetry in PostGIS -

point cloud

Wewillusethetechniqueswe'veusedinapreviousrecipe, Creating arbitrary 3D ob-
jects for PostGIS , of this chapter, to learn how to create and import a UAV-derived
point cloud in PostGIS.

One caveat before we begin is that while we will be working with geospatial data,
we will be doing so in relative space, rather than a known coordinate system. In
otherwords,thisapproachwillcalculateourdatasetinanarbitrarycoordinatesystem.
ST_Affine could be used in combination with the field measurements of locations
totransformourdataintoaknowncoordinatesystem,butisbeyondthescopeofthis
book.

Getting ready

Much like with the recipe, Creating arbitrary 3D objects for PostGIS , we will be
taking an image series and converting it into a point cloud. In this case, however,
our image series will be from UAV imagery. Download the image series from ht-
tp://www.packtpub.com/support and feed it into http://my3dscanner.com or a local
Bundler/PMVS solution, returning a point cloud, uas_points.ply .

TheinputtoPostGISisthesameasbefore.Deletethefirst14lines(header)ofthe
ply file and create a PostGIS table to accept the point cloud.

CREATE TABLE chp07.uas (
x double precision,
y double precision,
z double precision,
red integer,
green integer,
blue integer

);

Dependingonwhatsoftwareconstructedyourpointcloud,yourspecificcolumnsmay
vary.