Return the instants of a trajectory where the sampled raster value falls inside a float range

atRasterValue(tgeompoint,raster,floatspan,band integer DEFAULT 1) → tgeompoint

Evaluates raster_value at every instant of traj and returns the sub-trajectory restricted to the times when the pixel value lies within vspan. Returns NULL when no instant satisfies the condition.

WITH rast AS (
  SELECT ST_SetValues(
    ST_AddBand(
      ST_MakeEmptyRaster(3, 3, 0.0, 3.0, 1.0, -1.0, 0.0, 0.0, 4326),
      '32BF'::text, 0.0::float8, NULL::float8),
    1, 1, 1,
    ARRAY[[10.0::float4, 20.0::float4, 30.0::float4],
          [40.0::float4, 50.0::float4, 60.0::float4],
          [70.0::float4, 80.0::float4, 90.0::float4]]) AS r
)
SELECT asText(atRasterValue(
  tgeompoint 'SRID=4326;[POINT(0.5 2.5)@2000-01-01,
                          POINT(1.5 1.5)@2000-01-02,
                          POINT(0.5 0.5)@2000-01-03]',
  r, floatspan '[40, 90]'))
FROM rast;
-- {[POINT(1.5 1.5)@2000-01-02 00:00:00+00], [POINT(0.5 0.5)@2000-01-03 00:00:00+00]}

Return the instants of a trajectory where the sampled raster value falls outside a float range

minusRasterValue(tgeompoint,raster,floatspan,band integer DEFAULT 1) → tgeompoint

The complement of atRasterValue: returns the sub-trajectory restricted to the times when the pixel value lies outside vspan. Returns NULL when every instant satisfies the condition.

-- Keep only the instant whose raster value (10) is below 40
SELECT asText(minusRasterValue(traj, elev_raster, floatspan '[40, 9999]'))
FROM trips, elevation_raster;

Return true if the trajectory ever samples a raster pixel value inside a float range

eRasterValue(raster,tgeompoint,floatspan,band integer DEFAULT 1) → boolean

Returns true when at least one in-extent instant of traj samples a pixel value within vspan, false otherwise. Returns NULL only when the input is NULL.

-- Trips that ever crossed terrain above 200 m
SELECT tripid
FROM trips, elevation_raster
WHERE eRasterValue(elev_raster, trip4326, floatspan '[200, 9999]');

Return true if every in-raster-extent instant of the trajectory samples a pixel value inside a float range

aRasterValue(raster,tgeompoint,floatspan,band integer DEFAULT 1) → boolean

Returns true when every in-extent instant of traj samples a pixel value within vspan, false when at least one does not. Returns NULL only when the input is NULL.

-- Trips that stayed entirely below 100 m elevation
SELECT tripid
FROM trips, elevation_raster
WHERE aRasterValue(elev_raster, trip4326, floatspan '[0, 100]');