How to overlay a Shapefile on a WMS layer using Geotools?

Question

I am trying to overlay a shp file on wms layer using the example http://docs.geotools.org/latest/userguide/tutorial/raster/image.html.

Each time I want to read the format of the file to get a reader I get this error :

Exception in thread "main" java.lang.UnsupportedOperationException: Trying to get a reader from an unknown format.
at org.geotools.coverage.grid.io.UnknownFormat.getReader(UnknownFormat.java:62)
at com.qedrix.map.maplotr.Demo1.displayLayers(Demo1.java:127)
at com.qedrix.map.maplotr.Demo1.main(Demo1.java:260)

My code follows:

public class Demo1 {
private AbstractGridCoverage2DReader reader = null;
private StyleFactory sf = CommonFactoryFinder.getStyleFactory();
private FilterFactory2 ff = CommonFactoryFinder.getFilterFactory2();
/**
 * This method examines the names of the sample dimensions in the provided
 * coverage looking for "red...", "green..." and "blue..." (case insensitive
 * match). If these names are not found it uses bands 1, 2, and 3 for the
 * red, green and blue channels. It then sets up a raster symbolizer and
 * returns this wrapped in a Style.
 * 
 * @return a new Style object containing a raster symbolizer set up for RGB
 * image
 */
private Style createRGBStyle() {
 GridCoverage2D cov = null;
 try {
 cov = reader.read(null);
 } catch (IOException giveUp) {
 throw new RuntimeException(giveUp);
 }
 // We need at least three bands to create an RGB style
 int numBands = cov.getNumSampleDimensions();
 if (numBands < 3) {
 return null;
 }
 // Get the names of the bands
 String[] sampleDimensionNames = new String[numBands];
 for (int i = 0; i < numBands; i++) {
 GridSampleDimension dim = cov.getSampleDimension(i);
 sampleDimensionNames[i] = dim.getDescription().toString();
 }
 final int RED = 0, GREEN = 1, BLUE = 2;
 int[] channelNum = { -1, -1, -1 };
 // We examine the band names looking for "red...", "green...",
 // "blue...".
 // Note that the channel numbers we record are indexed from 1, not 0.
 for (int i = 0; i < numBands; i++) {
 String name = sampleDimensionNames[i].toLowerCase();
 if (name != null) {
 if (name.matches("red.*")) {
 channelNum[RED] = i + 1;
 } else if (name.matches("green.*")) {
 channelNum[GREEN] = i + 1;
 } else if (name.matches("blue.*")) {
 channelNum[BLUE] = i + 1;
 }
 }
 }
 // If we didn't find named bands "red...", "green...", "blue..."
 // we fall back to using the first three bands in order
 if (channelNum[RED] < 0 || channelNum[GREEN] < 0 || channelNum[BLUE] < 0) {
 channelNum[RED] = 1;
 channelNum[GREEN] = 2;
 channelNum[BLUE] = 3;
 }
 // Now we create a RasterSymbolizer using the selected channels
 SelectedChannelType[] sct = new SelectedChannelType[cov.getNumSampleDimensions()];
 ContrastEnhancement ce = sf.contrastEnhancement(ff.literal(1.0), ContrastMethod.NORMALIZE);
 for (int i = 0; i < 3; i++) {
 sct[i] = sf.createSelectedChannelType(String.valueOf(channelNum[i]), ce);
 }
 RasterSymbolizer sym = sf.getDefaultRasterSymbolizer();
 ChannelSelection sel = sf.channelSelection(sct[RED], sct[GREEN], sct[BLUE]);
 sym.setChannelSelection(sel);
 return SLD.wrapSymbolizers(sym);
}
public void displayLayers() {
 File rasterFile = fetchWmsImage();
 AbstractGridFormat format = GridFormatFinder.findFormat(rasterFile);
 this.reader = format.getReader(rasterFile);
 // Initially display the raster in greyscale using the
 // data from the first image band
 Style rasterStyle = createRGBStyle();
 // Create a basic style with yellow lines and no fill
 Style shpStyle = SLD.createPointStyle("point", Color.YELLOW, Color.GRAY, 0.0f, 1.5f);
 MapContent map = new MapContent();
 map.setTitle("ImageLab");
 MapViewport vp = new MapViewport();
 org.geotools.map.Layer rasterLayer = new GridReaderLayer(reader, rasterStyle);
 map.addLayer(rasterLayer);
 saveImage(map, "final.jpeg", 583);
}
public File fetchWmsImage() {
 URL url = null;
 try {
 url = new URL("http://184.106.187.247:8080/geoserver/rg/wms?version=1.1.0");
 } catch (MalformedURLException e) {
 // will not happen
 }
 WebMapServer wms = null;
 try {
 wms = new WebMapServer(url);
 WMSCapabilities capabilities = wms.getCapabilities();
 Layer[] layers = WMSUtils.getNamedLayers(capabilities);
 GetMapRequest request = wms.createGetMapRequest();
 request.setFormat("image/png");
 request.setDimensions("583", "420");
 request.setTransparent(true);
 request.setSRS("EPSG:900913");
 request.setBBox("-13019428.542822,3922163.1648461,-13013051.407366,3929863.8567165");
 //request.setProperty("isBaseLayer", "false");
 //request.setProperty("opacity", ".2");
 for (Layer layer : WMSUtils.getNamedLayers(capabilities)) {
 if (layer.getName().equals("rg:parcels"))
 request.addLayer(layer);
 }
 System.out.println(request.getFinalURL());
 GetMapResponse response = (GetMapResponse) wms.issueRequest(request);
 BufferedImage image = ImageIO.read(response.getInputStream());
 File rasterFile = new File("C:\\Users\\samabhik\\Workspace\\MAP\\data\\out.png");
 ImageIO.write(image, "png", rasterFile);
 try{
 Thread.sleep(2000);
 }catch(InterruptedException e){}
 return rasterFile;
 } catch (ServiceException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 } catch (IOException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 } finally {
 }
 return null;
}
public void saveImage(final MapContent map, final String file, final int imageWidth) {
 GTRenderer renderer = new StreamingRenderer();
 renderer.setMapContent(map);
 Rectangle imageBounds = null;
 ReferencedEnvelope mapBounds = null;
 try {
 mapBounds = map.getMaxBounds();
 double heightToWidth = mapBounds.getSpan(1) / mapBounds.getSpan(0);
 imageBounds = new Rectangle(0, 0, imageWidth, (int) Math.round(imageWidth * heightToWidth));
 } catch (Exception e) {
 // failed to access map layers
 throw new RuntimeException(e);
 }
 BufferedImage image = new BufferedImage(imageBounds.width, imageBounds.height, BufferedImage.TYPE_INT_RGB);
 Graphics2D gr = image.createGraphics();
 gr.setPaint(Color.WHITE);
 gr.fill(imageBounds);
 try {
 renderer.paint(gr, imageBounds, mapBounds);
 File fileToSave = new File(file);
 ImageIO.write(image, "jpeg", fileToSave);
 } catch (IOException e) {
 throw new RuntimeException(e);
 }
}
public static void main(String[] args) {
 Demo1 demo = new Demo1();
 demo.displayLayers();
}

}

My pom dependency looks like this:

<dependency>
 <groupId>org.geotools</groupId>
 <artifactId>gt-shapefile</artifactId>
 <version>${geotools.version}</version>
 </dependency>
 <dependency>
 <groupId>org.geotools</groupId>
 <artifactId>gt-swing</artifactId>
 <version>${geotools.version}</version>
 </dependency>
 <dependency>
 <groupId>org.geotools</groupId>
 <artifactId>gt-epsg-hsql</artifactId>
 <version>${geotools.version}</version>
 </dependency>
 <dependency>
 <groupId>org.geotools</groupId>
 <artifactId>gt-geotiff</artifactId>
 <version>${geotools.version}</version>
 </dependency>
 <dependency>
 <groupId>org.geotools</groupId>
 <artifactId>gt-image</artifactId>
 <version>${geotools.version}</version>
 </dependency>
 <dependency>
 <groupId>org.geotools</groupId>
 <artifactId>gt-wms</artifactId>
 <version>${geotools.version}</version>
 </dependency>
 <dependency>
 <groupId>org.geotools</groupId>
 <artifactId>gt-coverage</artifactId>
 <version>${geotools.version}</version>
 </dependency>
 <dependency>
 <groupId>org.geotools</groupId>
 <artifactId>gt-imageio-ext-gdal</artifactId>
 <version>${geotools.version}</version>
 </dependency>

I am using geotools version 9-SNAPSHOT

I have added the native libraries from gdal in java classpath in eclipse.

I am totally stuck and don't know what's wrong.

I even tested the geoserver WMS URL and it works:

http://184.106.187.247:8080/geoserver/rg/wms?SERVICE=WMS&LAYERS=rg:parcels&ISBASELAYER=false&FORMAT=image/png&OPACITY=.2&HEIGHT=420&TRANSPARENT=TRUE&REQUEST=GetMap&BBOX=-13019428.542822,3922163.1648461,-13013051.407366,3929863.8567165&WIDTH=583&STYLES=&SRS=EPSG:900913&VERSION=1.1.1

Just ran gdalinfo.exe to read the image content and it follows:

Driver: PNG/Portable Network Graphics
Files: ..\..\Workspace\MAP\data\out2.png
Size is 583, 420
Coordinate System is `'
Image Structure Metadata:
 INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left ( 0.0, 0.0)
Lower Left ( 0.0, 420.0)
Upper Right ( 583.0, 0.0)
Lower Right ( 583.0, 420.0)
Center ( 291.5, 210.0)
Band 1 Block=583x1 Type=Byte, ColorInterp=Red
 Mask Flags: PER_DATASET ALPHA
Band 2 Block=583x1 Type=Byte, ColorInterp=Green
 Mask Flags: PER_DATASET ALPHA
Band 3 Block=583x1 Type=Byte, ColorInterp=Blue
 Mask Flags: PER_DATASET ALPHA
Band 4 Block=583x1 Type=Byte, ColorInterp=Alpha

• R.K.: Is that the whole code? The imports are missing.
• R.K.: Are you using Maven?
• Qedrix: Yes using maven. I intentionally left out the imports.

Answer 1

I think the answer is to use a WMSMapLayer instead of saving the map to disk and trying to reload it.

 MapContext mapcontext = new DefaultMapContext();
 mapcontext.setTitle( wms.getCapabilities().getService().getTitle() );
 for( Layer wmsLayer : wmsLayers ){
 WMSMapLayer displayLayer = new WMSMapLayer(wms, wmsLayer );
 mapcontext.addLayer( displayLayer );
 }
 // Now display the map
 JMapFrame.showMap(mapcontext);

See this tutorial for more details.