RS_PixelAsCentroids

Introduction: Returns a list of the centroid point geometry, the pixel value and its raster X and Y coordinates for each pixel in the raster at the specified band. Each centroid represents the geometric center of the corresponding pixel's area.

Format: RS_PixelAsCentroids(raster: Raster, band: Integer)

Return type: Array<Struct<geom: Geometry, val: Double, x: Integer, y: Integer>>

Since: v1.5.1

SQL Example

SELECT ST_AsText(RS_PixelAsCentroids(raster, 1)) from rasters

Output:

[[POINT (-13065222 4021263.75),148.0,0,0], [POINT (-13065151 4021263.75),123.0,0,1], [POINT (-13065077 4021263.75),99.0,1,0], [POINT (-13065007 4021261.75),140.0,1,1]]

Spark SQL example for extracting Point, value, raster x and y coordinates:

val pointDf = sedona.read...
val rasterDf = sedona.read.format("binaryFile").load("/some/path/*.tiff")
var df = sedona.read.format("binaryFile").load("/some/path/*.tiff")
df = df.selectExpr("RS_FromGeoTiff(content) as raster")

df.selectExpr(
  "explode(RS_PixelAsCentroids(raster, 1)) as exploded"
).selectExpr(
  "exploded.geom as geom",
  "exploded.value as value",
  "exploded.x as x",
  "exploded.y as y"
).show(3)

Output:

+----------------------------------------------+-----+---+---+
|geom                                          |value|x  |y  |
+----------------------------------------------+-----+---+---+
|POINT (-13095781.835693639 4021226.5856936392)|0.0  |1  |1  |
|POINT (-13095709.507080918 4021226.5856936392)|0.0  |2  |1  |
|POINT (-13095637.178468198 4021226.5856936392)|0.0  |3  |1  |
+----------------------------------------------+-----+---+---+