Hi, I read this just by chance.
I had no answer from Sextante community then. I had to implement my own
version of the algorithm. However, I ended up not using it since it was no
longer necessary for my project -neither Sextante-.
I sent this implementation to Victor but had no answer. I post it here since
it may be useful to you. However, keep in mind a few considerations:
- I didn't implement it having efficiency in mind. It takes twice or more
than the original implementation to run the algorithm.
- I didn't test it very well since I didn't have to use it at the end.
Hope it helps.
Fernando
--------------
package com.example;
import java.awt.geom.Point2D;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.CoordinateFilter;
import com.vividsolutions.jts.geom.Envelope;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.Polygon;
import com.vividsolutions.jts.operation.union.CascadedPolygonUnion;
import es.unex.sextante.core.GeoAlgorithm;
import es.unex.sextante.core.Sextante;
import es.unex.sextante.dataObjects.IRasterLayer;
import es.unex.sextante.dataObjects.IVectorLayer;
import es.unex.sextante.exceptions.GeoAlgorithmExecutionException;
import es.unex.sextante.exceptions.RepeatedParameterNameException;
import es.unex.sextante.exceptions.UnsupportedOutputChannelException;
import es.unex.sextante.outputs.OutputVectorLayer;
import es.unex.sextante.rasterWrappers.GridExtent;
public class VectorizeAlgorithmReimplementado extends GeoAlgorithm {
public static final String LAYER = "LAYER";
public static final String RESULT = "RESULT";
private IRasterLayer m_Input;
private IVectorLayer m_Polygons;
public void defineCharacteristics() {
setName(Sextante.getText("Vectorizar_capa_raster"));
setGroup(Sextante.getText("Vectorizacion"));
setGeneratesUserDefinedRasterOutput(false);
try {
m_Parameters.addInputRasterLayer(LAYER,
Sextante.getText("Capa_de_entrada"), true);
addOutputVectorLayer(RESULT, Sextante.getText("Resultado"),
OutputVectorLayer.SHAPE_TYPE_POLYGON);
} catch (RepeatedParameterNameException e) {
Sextante.addErrorToLog(e);
}
}
public boolean processAlgorithm() throws GeoAlgorithmExecutionException
{
String sFields[] = new String[2];
Class<?> types[] = { Integer.class, Double.class };
m_Input = m_Parameters.getParameterValueAsRasterLayer(LAYER);
m_Input.setFullExtent();
sFields[0] = "ID";
sFields[1] = m_Input.getName();
m_Polygons = getNewVectorLayer(RESULT,
Sextante.getText("Resultado"),
IVectorLayer.SHAPE_TYPE_POLYGON, types, sFields);
createPolygons();
return !m_Task.isCanceled();
}
private void createPolygons() throws UnsupportedOutputChannelException {
double dValue;
int m_iNX = m_Input.getNX();
int m_iNY = m_Input.getNY();
Map<Double, List<Polygon>> classes = new HashMap<Double,
List<Polygon>>();
Map<Double, Integer> ids = new HashMap<Double, Integer>();
GeometryFactory gridGeometryFactory = new GeometryFactory();
int id = 0;
for (int y = 0; y < m_iNY && setProgress(y, m_iNY); y++) {
for (int x = 0; x < m_iNX; x++) {
dValue = m_Input.getCellValueAsDouble(x, y);
Polygon square = (Polygon) gridGeometryFactory
.toGeometry(new Envelope(x, x + 1, y, y + 1));
List<Polygon> clazz = classes.get(dValue);
if (clazz == null) {
clazz = new LinkedList<Polygon>();
ids.put(dValue, id);
classes.put(dValue, clazz);
id++;
}
clazz.add(square);
}
}
final GridExtent wge = m_Input.getWindowGridExtent();
final double halfCellSize = wge.getCellSize() / 2;
for (Map.Entry<Double, List<Polygon>> entry : classes.entrySet()) {
double value = entry.getKey();
List<Polygon> clazz = entry.getValue();
CascadedPolygonUnion cascadedPolygonUnion = new
CascadedPolygonUnion(
clazz);
Geometry classGeometry = cascadedPolygonUnion.union();
classGeometry.apply(new CoordinateFilter() {
@Override
public void filter(Coordinate arg0) {
Point2D translated = wge.getWorldCoordsFromGridCoords(
(int) arg0.x, (int) arg0.y);
arg0.x = translated.getX() - halfCellSize;
arg0.y = translated.getY() + halfCellSize;
}
});
Object values[] = new Object[2];
values[0] = ids.get(value);
values[1] = value;
m_Polygons.addFeature(classGeometry, values);
}
}
}
Hi list,
>
> Last March a user called Fernando had a problem with vectorize
> algorithm (see below). I would like to know
> if there is any solution because I have had the same problem.
>
> Thank you,
>
> Ibon
>
> 2011/3/14 Fernando Barbat <fbar...@gmail.com>:
> > Hi list,
> >
> > I am trying to use VectorizeAlgorithm of Sextante 0.6 to vectorize a
> raster
> > (using plain Java and GeoTools 2.6). However, the resulting shapefile is
> not
> > what one would expect. It has two polygons which are not vectorized
> > properly.
> >
> > I can share both raster and Sextante-vectorized version if someone is
> > interested.
> >
> > Any idea?
> >
> > Thanks.
> >
> > Fernando
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