def test_elevation(self):
# Create a simple fake DEM
conn = connections[DEFAULT_DB_ALIAS]
cur = conn.cursor()
cur.execute('CREATE TABLE mnt (rid serial primary key, rast raster)')
cur.execute('INSERT INTO mnt (rast) VALUES (ST_MakeEmptyRaster(3, 3, 0, 3, 1, -1, 0, 0, %s))', [settings.SRID])
cur.execute('UPDATE mnt SET rast = ST_AddBand(rast, \'16BSI\')')
for x in range(1, 4):
for y in range(1, 4):
cur.execute('UPDATE mnt SET rast = ST_SetValue(rast, %s, %s, %s::float)', [x, y, x+y])
conn.commit_unless_managed()
# Create a geometry and check elevation-based indicators
p = Path(geom=LineString((1.5,1.5,0), (2.5,1.5,0), (1.5,2.5,0)))
self.assertEqual(p.ascent, 0)
self.assertEqual(p.descent, 0)
self.assertEqual(p.min_elevation, 0)
self.assertEqual(p.max_elevation, 0)
p.save()
self.assertEqual(p.ascent, 1)
self.assertEqual(p.descent, -2)
self.assertEqual(p.min_elevation, 3)
self.assertEqual(p.max_elevation, 5)
# Check elevation profile
profile = p.get_elevation_profile()
self.assertEqual(len(profile), 3)
self.assertEqual(profile[0][0], 0.0)
self.assertEqual(profile[0][1], 4)
self.assertTrue(1.4 < profile[1][0] < 1.5)
self.assertEqual(profile[1][1], 5)
self.assertTrue(3.8 < profile[2][0] < 3.9)
self.assertEqual(profile[2][1], 3)
def test_elevation_path(self):
# Create a geometry and check elevation-based indicators
p = Path(geom=LineString((1.5,1.5,0), (2.5,1.5,0), (1.5,2.5,0)))
self.assertEqual(p.ascent, 0)
self.assertEqual(p.descent, 0)
self.assertEqual(p.min_elevation, 0)
self.assertEqual(p.max_elevation, 0)
p.save()
self.assertEqual(p.ascent, 1)
self.assertEqual(p.descent, -2)
self.assertEqual(p.min_elevation, 3)
self.assertEqual(p.max_elevation, 5)
# Check elevation profile
profile = p.get_elevation_profile()
self.assertEqual(len(profile), 4) # minimum possible (since p.length < sampling resolution)
self.assertEqual(profile[0][0], 0.0)
self.assertEqual(profile[0][3], 4)
self.assertTrue(2.4 < profile[-1][0] < 2.5) # p.geom.length
self.assertEqual(profile[-1][3], 3)