RS_Values - Wherobots

Returns the values at the given points or grid coordinates in the raster. If no band number is specified it defaults to 1. RS_Values is similar to RS_Value but operates on an array of points or grid coordinates. RS_Values can be significantly faster since a raster only has to be loaded once for several points.

Since v1.5.1, if the coordinate reference system (CRS) of the input points geometries differs from that of the raster, then points will be transformed to match the CRS of the raster. If the raster or points doesn’t have a CRS then it will default to 4326/WGS84.

Integer grid coordinates are 1-based: (1, 1) is the upper-left pixel. When migrating from a runtime with zero-based grid coordinates, add 1 to both the column and row. Geometry coordinates and band indices are unchanged. See Geometry and raster API migration.

Signatures

RS_Values (raster: Raster, points: ARRAY[Geometry])

RS_Values (raster: Raster, points: ARRAY[Geometry], band: Integer)

RS_Values (raster: Raster, xCoordinates: ARRAY[Integer], yCoordinates: ARRAY[Integer], band: Integer)

Parameters

Raster

required

The input raster.

ARRAY[Integer]

The 1-based pixel columns.

ARRAY[Integer]

The 1-based pixel rows.

Integer

The band index.

ARRAY[Geometry]

The points value.

Return type

An array of double values.

Examples

For Array of Point geometries:

SELECT RS_Values(raster, Array(ST_Point(-1307.5, 400.8), ST_Point(-1403.3, 399.1)))
FROM raster_table

For Arrays of grid coordinates:

SELECT RS_Values(raster, Array(5, 6), Array(4, 3), 1) FROM raster_table

Array(5.0, 3.0)

Spark SQL example for joining a point dataset with a raster dataset:

val pointDf = sedona.read...
val rasterDf = sedona.read.format("binaryFile").load("/some/path/*.tiff")
  .withColumn("raster", expr("RS_FromGeoTiff(content)"))
  .withColumn("envelope", expr("RS_Envelope(raster)"))

// Join the points with the raster extent and aggregate points to arrays.
// We only use the path and envelope of the raster to keep the shuffle as small as possible.
val df = pointDf.join(rasterDf.select("path", "envelope"), expr("ST_Within(point_geom, envelope)"))
  .groupBy("path")
  .agg(collect_list("point_geom").alias("point"), collect_list("point_id").alias("id"))

df.join(rasterDf, "path")
  .selectExpr("explode(arrays_zip(id, point, RS_Values(raster, point))) as result")
  .selectExpr("result.*")
  .show()

+----+------------+-------+
| id | point      | value |
+----+------------+-------+
|  4 | POINT(1 1) |   3.0 |
|  5 | POINT(2 2) |   7.0 |
+----+------------+-------+

​Signatures

​Parameters

​Return type

​Examples

Signatures

Parameters

Return type

Examples