[SEDONA-271] Add raster function RS_SRID

common/src/main/java/org/apache/sedona/common/raster/Functions.java

@@ -18,30 +18,48 @@
 import org.geotools.coverage.grid.GridGeometry2D;
 import org.geotools.geometry.DirectPosition2D;
 import org.geotools.geometry.Envelope2D;
+import org.geotools.referencing.CRS;
+import org.geotools.referencing.crs.DefaultEngineeringCRS;
 import org.locationtech.jts.geom.*;
+import org.opengis.referencing.FactoryException;
+import org.opengis.referencing.crs.CoordinateReferenceSystem;
 import org.opengis.referencing.operation.TransformException;
 
 import java.awt.image.Raster;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 import java.util.function.DoublePredicate;
 import java.util.stream.Collectors;
 import java.util.stream.DoubleStream;
 
 public class Functions {
 
-    public static Geometry envelope(GridCoverage2D raster) {
+    public static Geometry envelope(GridCoverage2D raster) throws FactoryException {
         Envelope2D envelope2D = raster.getEnvelope2D();
 
         Envelope envelope = new Envelope(envelope2D.getMinX(), envelope2D.getMaxX(), envelope2D.getMinY(), envelope2D.getMaxY());
-        return new GeometryFactory().toGeometry(envelope);
+        int srid = srid(raster);
+        return new GeometryFactory(new PrecisionModel(), srid).toGeometry(envelope);
     }
 
     public static int numBands(GridCoverage2D raster) {
         return raster.getNumSampleDimensions();
     }
 
+    public static int srid(GridCoverage2D raster) throws FactoryException {
+        CoordinateReferenceSystem crs = raster.getCoordinateReferenceSystem();
+        if (crs instanceof DefaultEngineeringCRS) {
+            // GeoTools defaults to internal non-standard epsg codes, like 404000, if crs is missing.
+            // We need to check for this case and return 0 instead.
+            if (((DefaultEngineeringCRS) crs).isWildcard()) {
+                return 0;
+            }
+        }
+        return Optional.ofNullable(CRS.lookupEpsgCode(crs, true)).orElse(0);
+    }
+
     public static Double value(GridCoverage2D rasterGeom, Geometry geometry, int band) throws TransformException {
         return values(rasterGeom, Collections.singletonList(geometry), band).get(0);
     }

common/src/test/java/org/apache/sedona/common/raster/ConstructorsTest.java

@@ -16,6 +16,7 @@
 import org.geotools.coverage.grid.GridCoverage2D;
 import org.junit.Test;
 import org.locationtech.jts.geom.Geometry;
+import org.opengis.referencing.FactoryException;
 
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
@@ -25,7 +26,7 @@
 public class ConstructorsTest extends RasterTestBase {
 
     @Test
-    public void fromArcInfoAsciiGrid() throws IOException {
+    public void fromArcInfoAsciiGrid() throws IOException, FactoryException {
         GridCoverage2D gridCoverage2D = Constructors.fromArcInfoAsciiGrid(arc.getBytes(StandardCharsets.UTF_8));
 
         Geometry envelope = Functions.envelope(gridCoverage2D);
@@ -39,7 +40,7 @@ public void fromArcInfoAsciiGrid() throws IOException {
     }
 
     @Test
-    public void fromGeoTiff() throws IOException {
+    public void fromGeoTiff() throws IOException, FactoryException {
         GridCoverage2D gridCoverage2D = Constructors.fromGeoTiff(geoTiff);
 
         Geometry envelope = Functions.envelope(gridCoverage2D);

common/src/test/java/org/apache/sedona/common/raster/FunctionsTest.java

@@ -18,6 +18,7 @@
 import org.locationtech.jts.geom.Geometry;
 import org.locationtech.jts.geom.GeometryFactory;
 import org.locationtech.jts.geom.Point;
+import org.opengis.referencing.FactoryException;
 import org.opengis.referencing.operation.TransformException;
 
 import java.util.Arrays;
@@ -29,11 +30,13 @@
 public class FunctionsTest extends RasterTestBase {
 
     @Test
-    public void envelope() {
+    public void envelope() throws FactoryException {
         Geometry envelope = Functions.envelope(oneBandRaster);
         assertEquals(3600.0d, envelope.getArea(), 0.1d);
         assertEquals(378922.0d + 30.0d, envelope.getCentroid().getX(), 0.1d);
         assertEquals(4072345.0d + 30.0d, envelope.getCentroid().getY(), 0.1d);
+
+        assertEquals(4326, Functions.envelope(multiBandRaster).getSRID());
     }
 
     @Test
@@ -42,6 +45,12 @@ public void testNumBands() {
         assertEquals(4, Functions.numBands(multiBandRaster));
     }
 
+    @Test
+    public void testSrid() throws FactoryException {
+        assertEquals(0, Functions.srid(oneBandRaster));
+        assertEquals(4326, Functions.srid(multiBandRaster));
+    }
+
     @Test
     public void value() throws TransformException {
         assertNull("Points outside of the envelope should return null.", Functions.value(oneBandRaster, point(1, 1), 1));

docs/api/sql/Raster-operators.md

@@ -35,6 +35,24 @@ Output:
 4
 ```
 
+### RS_SRID
+
+Introduction: Returns the spatial reference system identifier (SRID) of the raster geometry.
+
+Format: `RS_SRID (raster: Raster)`
+
+Since: `v1.4.1`
+
+Spark SQL example:
+```sql
+SELECT RS_SRID(raster) FROM raster_table
+```
+
+Output:
+```
+3857
+```
+
 ### RS_Value
 
 Introduction: Returns the value at the given point in the raster.

sql/src/main/scala/org/apache/sedona/sql/UDF/Catalog.scala

@@ -173,6 +173,7 @@ object Catalog {
     function[RS_FromGeoTiff](),
     function[RS_Envelope](),
     function[RS_NumBands](),
+    function[RS_SRID](),
     function[RS_Value](1),
     function[RS_Values](1)
   )

sql/src/main/scala/org/apache/spark/sql/sedona_sql/expressions/raster/Functions.scala

@@ -855,6 +855,29 @@ case class RS_NumBands(inputExpressions: Seq[Expression]) extends Expression wit
   override def inputTypes: Seq[AbstractDataType] = Seq(RasterUDT)
 }
 
+case class RS_SRID(inputExpressions: Seq[Expression]) extends Expression with CodegenFallback with ExpectsInputTypes {
+  override def nullable: Boolean = true
+
+  override def eval(input: InternalRow): Any = {
+    val raster = inputExpressions(0).toRaster(input)
+    if (raster == null) {
+      null
+    } else {
+      Functions.srid(raster)
+    }
+  }
+
+  override def dataType: DataType = IntegerType
+
+  override def children: Seq[Expression] = inputExpressions
+
+  protected def withNewChildrenInternal(newChildren: IndexedSeq[Expression]) = {
+    copy(inputExpressions = newChildren)
+  }
+
+  override def inputTypes: Seq[AbstractDataType] = Seq(RasterUDT)
+}
+
 case class RS_Value(inputExpressions: Seq[Expression]) extends Expression with CodegenFallback with ExpectsInputTypes {
 
   override def nullable: Boolean = true

sql/src/test/scala/org/apache/sedona/sql/rasteralgebraTest.scala

@@ -290,6 +290,17 @@ class rasteralgebraTest extends TestBaseScala with BeforeAndAfter with GivenWhen
       assert(result == 1)
     }
 
+    it("Passed RS_SRID should handle null values") {
+      val result = sparkSession.sql("select RS_SRID(null)").first().get(0)
+      assert(result == null)
+    }
+
+    it("Passed RS_SRID with raster") {
+      val df = sparkSession.read.format("binaryFile").load(resourceFolder + "raster/test1.tiff")
+      val result = df.selectExpr("RS_SRID(RS_FromGeoTiff(content))").first().getInt(0)
+      assert(result == 3857)
+    }
+
     it("Passed RS_Value should handle null values") {
       val result = sparkSession.sql("select RS_Value(null, null)").first().get(0)
       assert(result == null)