[SEDONA-446] Add floating point datatype support in RS_AsBase64 (apac…

…he#1146)

Co-authored-by: John Bampton <jbampton@users.noreply.github.com>

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

@@ -135,7 +135,11 @@ public static byte[] asArcGrid(GridCoverage2D raster) {
     public static String asBase64(GridCoverage2D raster) throws IOException {
         ByteArrayOutputStream out = new ByteArrayOutputStream();
         RenderedImage renderedImage = raster.getRenderedImage();
-        ImageIO.write(renderedImage, "png", out);
+        if (RasterUtils.isDataTypeIntegral(RasterUtils.getDataTypeCode(RasterBandAccessors.getBandType(raster)))) {
+            ImageIO.write(renderedImage, "png", out);
+        } else {
+            ImageIO.write(renderedImage, "tiff", out);
+        }
         return Base64.getEncoder().encodeToString(out.toByteArray());
     }
 

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

@@ -23,9 +23,11 @@
 import org.junit.Test;
 import org.opengis.referencing.FactoryException;
 
+import javax.imageio.ImageIO;
 import java.io.File;
 import java.io.IOException;
 import java.net.URLConnection;
+import java.util.Arrays;
 
 
 import static org.junit.Assert.*;
@@ -42,6 +44,15 @@ public void testAsBase64() throws IOException {
         assertTrue(resultRaw.startsWith("iVBORw0KGgoAAAANSUhEUgAABaAAAALQCAMAAABR+ye1AAADAFBMVEXE9/W48vOq7PGa5u6L3"));
     }
 
+    @Test
+    public void testAsBase64Float() throws IOException {
+        double[] bandData = {202.125, 101.221, 7.468, 27.575, 18.463, 106.103, 80.995, 213.73, 249.73, 147.455, 202.669, 223.379, 6.898, 64.108, 81.585, 51.162, 198.681, 147.957, 14.233, 14.146, 209.691, 121.825, 197.658, 235.804, 129.798};
+        GridCoverage2D raster = RasterConstructors.makeNonEmptyRaster(1, "d", 5, 5, 1, 1, 1, 1, 0, 0, 4326, new double[][] {bandData});
+
+        String resultRaw = RasterOutputs.asBase64(raster);
+        assertTrue(resultRaw.startsWith("TU0AKgAAAAgADQEAAAMAAAABAAUAAAEBAAMAAAABAAUAAAECA"));
+    }
+
     @Test
     public void testAsPNG() throws IOException, FactoryException {
         String dirPath = System.getProperty("user.dir") + "/target/testAsPNGFunction/";

docs/api/sql/Raster-visualizer.md

@@ -4,7 +4,10 @@ Sedona offers some APIs to aid in easy visualization of a raster object.
 Sedona offers APIs to visualize a raster in an image form. This API only works for rasters with byte data, and bands <= 4 (Grayscale - RGBA). You can check the data type of an existing raster by using [RS_BandPixelType](../Raster-operators/#rs_bandpixeltype) or create your own raster by passing 'B' while using [RS_MakeEmptyRaster](../Raster-loader/#rs_makeemptyraster).
 
 ### RS_AsBase64
-Introduction: Returns a base64 encoded string of the given raster. This function internally takes the first 4 bands as RGBA, and converts them to the PNG format, finally produces a base64 string. To visualize other bands, please use it together with `RS_Band`. You can take the resulting base64 string in [an online viewer](https://base64-viewer.onrender.com/) to check how the image looks like.
+Introduction: Returns a base64 encoded string of the given raster. If the datatype is integral then this function internally takes the first 4 bands as RGBA, and converts them to the PNG format, finally produces a base64 string. When the datatype is not integral, the function converts the raster to TIFF format, and then generates a base64 string. To visualize other bands, please use it together with `RS_Band`. You can take the resulting base64 string in [an online viewer](https://base64-viewer.onrender.com/) to check how the image looks like.
+
+!!!Warning
+    This is not recommended for large files.
 
 Format: `RS_AsBase64(raster: Raster)`