112 lines
3.3 KiB
Java
112 lines
3.3 KiB
Java
package btools.mapcreator;
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import java.io.*;
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import btools.util.*;
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//
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// Encode/decode a raster
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//
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public class RasterCoder {
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public void encodeRaster(SrtmRaster raster, OutputStream os) throws IOException {
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DataOutputStream dos = new DataOutputStream(os);
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long t0 = System.currentTimeMillis();
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dos.writeInt(raster.ncols);
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dos.writeInt(raster.nrows);
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dos.writeBoolean(raster.halfcol);
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dos.writeDouble(raster.xllcorner);
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dos.writeDouble(raster.yllcorner);
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dos.writeDouble(raster.cellsize);
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dos.writeShort(raster.noDataValue);
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_encodeRaster(raster, os);
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long t1 = System.currentTimeMillis();
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System.out.println("finished encoding in " + (t1 - t0) + " ms");
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}
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public SrtmRaster decodeRaster(InputStream is) throws IOException {
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DataInputStream dis = new DataInputStream(is);
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long t0 = System.currentTimeMillis();
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SrtmRaster raster = new SrtmRaster();
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raster.ncols = dis.readInt();
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raster.nrows = dis.readInt();
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raster.halfcol = dis.readBoolean();
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raster.xllcorner = dis.readDouble();
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raster.yllcorner = dis.readDouble();
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raster.cellsize = dis.readDouble();
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raster.noDataValue = dis.readShort();
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raster.eval_array = new short[raster.ncols * raster.nrows];
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_decodeRaster(raster, is);
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raster.usingWeights = raster.ncols > 6001;
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long t1 = System.currentTimeMillis();
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System.out.println("finished decoding in " + (t1 - t0) + " ms ncols=" + raster.ncols + " nrows=" + raster.nrows);
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return raster;
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}
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private void _encodeRaster(SrtmRaster raster, OutputStream os) throws IOException {
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MixCoderDataOutputStream mco = new MixCoderDataOutputStream(os);
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int nrows = raster.nrows;
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int ncols = raster.ncols;
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short[] pixels = raster.eval_array;
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int colstep = raster.halfcol ? 2 : 1;
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for (int row = 0; row < nrows; row++) {
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short lastval = Short.MIN_VALUE; // nodata
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for (int col = 0; col < ncols; col += colstep) {
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short val = pixels[row * ncols + col];
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if (val == -32766) {
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val = lastval; // replace remaining (border) skips
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} else {
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lastval = val;
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}
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// remap nodata
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int code = val == Short.MIN_VALUE ? -1 : (val < 0 ? val - 1 : val);
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mco.writeMixed(code);
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}
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}
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mco.flush();
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}
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private void _decodeRaster(SrtmRaster raster, InputStream is) throws IOException {
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MixCoderDataInputStream mci = new MixCoderDataInputStream(is);
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int nrows = raster.nrows;
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int ncols = raster.ncols;
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short[] pixels = raster.eval_array;
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int colstep = raster.halfcol ? 2 : 1;
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for (int row = 0; row < nrows; row++) {
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for (int col = 0; col < ncols; col += colstep) {
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int code = mci.readMixed();
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// remap nodata
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int v30 = code == -1 ? Short.MIN_VALUE : (code < 0 ? code + 1 : code);
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if (raster.usingWeights && v30 > -32766) {
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v30 *= 2;
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}
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pixels[row * ncols + col] = (short) (v30);
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}
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if (raster.halfcol) {
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for (int col = 1; col < ncols - 1; col += colstep) {
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int l = (int) pixels[row * ncols + col - 1];
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int r = (int) pixels[row * ncols + col + 1];
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short v30 = Short.MIN_VALUE; // nodata
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if (l > -32766 && r > -32766) {
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v30 = (short) ((l + r) / 2);
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}
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pixels[row * ncols + col] = v30;
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}
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}
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}
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}
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}
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