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Merge pull request #553 from zod/elev-source-cleanup
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Cleanup hgt reader
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@afischerdev
afischerdev committed May 17, 2023
2 parents 0388d55 + 53a5f44 commit 11a9843
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Showing 2 changed files with 46 additions and 335 deletions.
112 changes: 46 additions & 66 deletions brouter-map-creator/src/main/java/btools/mapcreator/ConvertLidarTile.java
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Original file line number Diff line number Diff line change
Expand Up @@ -5,22 +5,26 @@
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

public class ConvertLidarTile {
public static int NROWS;
public static int NCOLS;
public static int ROW_LENGTH;
private static int NROWS;
private static int NCOLS;

public static final short NODATA2 = -32767; // hgt-formats nodata
public static final short NODATA = Short.MIN_VALUE;

public static final int SRTM3_ROW_LENGTH = 1200; // number of elevation values per line
public static final int SRTM1_ROW_LENGTH = 3600; //-- New file resolution is 3601x3601
private static final String HGT_FILE_EXT = ".hgt";
private static final int HGT_BORDER_OVERLAP = 1;
private static final int HGT_3ASEC_ROWS = 1201; // 3 arc second resolution (90m)
private static final int HGT_3ASEC_FILE_SIZE = HGT_3ASEC_ROWS * HGT_3ASEC_ROWS * Short.BYTES;
private static final int HGT_1ASEC_ROWS = 3601; // 1 arc second resolution (30m)

static short[] imagePixels;

Expand All @@ -30,8 +34,8 @@ private static void readHgtZip(String filename, int rowOffset, int colOffset) th
for (; ; ) {
ZipEntry ze = zis.getNextEntry();
if (ze == null) break;
if (ze.getName().endsWith(".hgt")) {
readHgtFromStream(zis, rowOffset, colOffset, 1200);
if (ze.getName().toLowerCase().endsWith(HGT_FILE_EXT)) {
readHgtFromStream(zis, rowOffset, colOffset, HGT_3ASEC_ROWS);
return;
}
}
Expand All @@ -40,20 +44,20 @@ private static void readHgtZip(String filename, int rowOffset, int colOffset) th
}
}

private static void readHgtFromStream(InputStream is, int rowOffset, int colOffset, int row_length)
private static void readHgtFromStream(InputStream is, int rowOffset, int colOffset, int rowLength)
throws Exception {
DataInputStream dis = new DataInputStream(new BufferedInputStream(is));
for (int ir = 0; ir < row_length + 1; ir++) {
for (int ir = 0; ir < rowLength; ir++) {
int row = rowOffset + ir;

for (int ic = 0; ic < row_length + 1; ic++) {
for (int ic = 0; ic < rowLength; ic++) {
int col = colOffset + ic;

int i1 = dis.read(); // msb first!
int i0 = dis.read();

if (i0 == -1 || i1 == -1)
throw new RuntimeException("unexcepted end of file reading hgt entry!");
throw new RuntimeException("unexpected end of file reading hgt entry!");

short val = (short) ((i1 << 8) | i0);

Expand Down Expand Up @@ -191,80 +195,56 @@ public static void main(String[] args) throws Exception {
}

public SrtmRaster getRaster(File f, double lon, double lat) throws Exception {
long fileSize;
InputStream inputStream;

if (f.getName().toLowerCase().endsWith(".zip")) {
ZipInputStream zis = new ZipInputStream(new BufferedInputStream(new FileInputStream(f)));
try {
for (; ; ) {
ZipEntry ze = zis.getNextEntry();
if (ze == null) break;
if (ze.getName().toLowerCase().endsWith(".hgt")) {
if (ze.getSize() > ((SRTM3_ROW_LENGTH + 1) * (SRTM3_ROW_LENGTH + 1) * 2)) {
ROW_LENGTH = SRTM1_ROW_LENGTH;
} else {
ROW_LENGTH = SRTM3_ROW_LENGTH;
}
// stay a 1x1 raster
NROWS = ROW_LENGTH + 1;
NCOLS = ROW_LENGTH + 1;

imagePixels = new short[NROWS * NCOLS]; // 650 MB !

// prefill as NODATA
for (int row = 0; row < NROWS; row++) {
for (int col = 0; col < NCOLS; col++) {
imagePixels[row * NCOLS + col] = NODATA;
}
}
readHgtFromStream(zis, 0, 0, ROW_LENGTH);
break;
}
for (; ; ) {
ZipEntry ze = zis.getNextEntry();
if (ze == null) {
throw new FileNotFoundException(f.getName() + " doesn't contain a " + HGT_FILE_EXT + " file.");
}
if (ze.getName().toLowerCase().endsWith(HGT_FILE_EXT)) {
fileSize = ze.getSize();
inputStream = zis;
break;
}
} finally {
zis.close();
}
} else {
if (f.length() > ((SRTM3_ROW_LENGTH + 1) * (SRTM3_ROW_LENGTH + 1) * 2)) {
ROW_LENGTH = SRTM1_ROW_LENGTH;
} else {
ROW_LENGTH = SRTM3_ROW_LENGTH;
}
// stay a 1x1 raster
NROWS = ROW_LENGTH + 1;
NCOLS = ROW_LENGTH + 1;

imagePixels = new short[NROWS * NCOLS]; // 650 MB !
fileSize = f.length();
inputStream = new FileInputStream(f);
}

// prefill as NODATA
for (int row = 0; row < NROWS; row++) {
for (int col = 0; col < NCOLS; col++) {
imagePixels[row * NCOLS + col] = NODATA;
}
}
FileInputStream dis = new FileInputStream(f);
try {
readHgtFromStream(dis, 0, 0, ROW_LENGTH);
} finally {
dis.close();
}
int rowLength;
if (fileSize > HGT_3ASEC_FILE_SIZE) {
rowLength = HGT_1ASEC_ROWS;
} else {
rowLength = HGT_3ASEC_ROWS;
}

System.out.println("read file " + f + " rl " + ROW_LENGTH);

boolean halfCol5 = false; // no halfcol tiles in lidar data (?)
// stay at 1 deg * 1 deg raster
NROWS = rowLength;
NCOLS = rowLength;

imagePixels = new short[NROWS * NCOLS];

// prefill as NODATA
Arrays.fill(imagePixels, NODATA);
readHgtFromStream(inputStream, 0, 0, rowLength);
inputStream.close();

SrtmRaster raster = new SrtmRaster();
raster.nrows = NROWS;
raster.ncols = NCOLS;
raster.halfcol = halfCol5;
raster.halfcol = false; // assume full resolution
raster.noDataValue = NODATA;
raster.cellsize = 1. / (double) ROW_LENGTH;
raster.cellsize = 1. / (double) (rowLength - HGT_BORDER_OVERLAP);
raster.xllcorner = (int) (lon < 0 ? lon - 1 : lon); //onDegreeStart - raster.cellsize;
raster.yllcorner = (int) (lat < 0 ? lat - 1 : lat); //latDegreeStart - raster.cellsize;
raster.eval_array = imagePixels;

return raster;

}

}
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