Database Reference
In-Depth Information
radians(0)::numeric, radians(heading)::numeric,
radians(roll)::numeric,radians(40)::numeric,
radians(50)::numeric, 1000::numeric) AS the_geom
FROM chp07.uas_locations
WHERE fileName = 'IMG_0512.JPG';
To intersect this with our footprints, our terrain model will need to be a volumetric.
We can make it so using
ST_Extrude
.
CREATE TABLE chp07.lidar_tin_extruded AS
SELECT ST_Extrude(the_geom, 0,0,1) AS
the_geom FROM
chp07.lidar_tin;
CREATE INDEX
chp07_lidar_tin_extruded_the_geom_3dx ON
chp07.lidar_tin_extruded USING gist(the_geom
gist_geometry_ops_nd);
We complete the operation by calculating the intersection with our footprints.
DROP TABLE IF EXISTS chp07.viewshed_true;
CREATE TABLE chp07.viewshed_true AS
SELECT
ST_3DIntersection(ST_SetSRID(v.the_geom, 3734),
ST_SetSRID(t.the_geom, 3734))
FROM chp07.viewshed v,
chp07.lidar_tin_extruded t
WHERE
ST_3DIntersects(ST_SetSRID(v.the_geom, 3734),
ST_SetSRID(t.the_geom, 3734));
Whencomparedwithanaïveun-intersectedestimateofafootprint(anewlycalcu-
latedfootprintinblueandanoldoneingreen),wefindalargeimprovementinthe
intersection.
