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Add resampling code

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This commit is contained in:
Gareth Evans
2017-06-01 22:03:50 +01:00
parent d2919ece4d
commit 9fa61bc68d
4 changed files with 98 additions and 6 deletions
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74
inputs.cc
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@@ -9,6 +9,78 @@
#include "main.hh"
#include "tiles.hh"
/*
* resample_data
* This is used to resample tile data. It is particularly designed for
* use with LIDAR tiles where the resolution can be anything up to 2m.
* This function is capable of merging neighbouring pixel values
* The scaling factor is the distance to merge pixels.
* NOTE: This means that new resolutions can only increment in multiples of the original
* (ie 2m LIDAR can be 4/6/8/... and 20m can be 40/60)
*/
int resample_data(int scaling_factor){
short **new_data;
/* Tile width and height is guaranteed to be IPPD.
* We now need to calculate the new width and height */
size_t new_ippd = ((IPPD+1) / scaling_factor);
max_elevation = -32768;
min_elevation = 32768;
for (int indx = 0; indx < MAXPAGES; indx++) {
/* Check if this is a valid tile. Uninitialized tiles have this default value */
if (dem[indx].max_el == 32768)
continue;
/* Now we allocate the replacement data arrays */
if ((new_data = new short *[new_ippd]) == NULL) {
return ENOMEM;
}
for (size_t i = 0; i < new_ippd; i++) {
if ((new_data[i] = new short[new_ippd]) == NULL) {
return ENOMEM; // If this happens we will leak but thats ok because we must bail anyway
}
}
/* Nearest neighbour normalization. For each subsample of the original, simply
* assign the value in the top left to the new pixel */
for (size_t x = 0, i = 0; i < new_ippd; x += scaling_factor, i++) {
for (size_t y = 0, j = 0; j < new_ippd; y += scaling_factor, j++){
// fprintf(stderr,"[%d,%d,%d,%d] => %d\n", dem[indx].data[x][y], dem[indx].data[x][y+1], dem[indx].data[x+1][y], dem[indx].data[x+1][y+1], dem[indx].data[x][y]);
new_data[i][j] = dem[indx].data[x][y];
}
}
/* We need to fixup the min/max elevations */
for (size_t i = 0; i < new_ippd; i++) {
for (size_t j = 0; j < new_ippd; j++) {
if (new_data[i][j] > dem[indx].max_el)
dem[indx].max_el = new_data[i][j];
if (new_data[i][j] > max_elevation)
max_elevation = new_data[i][j];
if (new_data[i][j] < dem[indx].min_el)
dem[indx].min_el = new_data[i][j];
if (new_data[i][j] < min_elevation)
min_elevation = new_data[i][j];
}
}
/* Resampling complete, delete the original and assign the new values */
for (size_t i = 0; i < IPPD; i++)
delete [] dem[indx].data[i];
delete [] dem[indx].data;
dem[indx].data = new_data;
}
/* Report to the user */
fprintf(stderr, "Resampling IPPD %d->%d min/max el %d/%d\n", IPPD, new_ippd, min_elevation, max_elevation);
/* Finally, set the new IPPD value */
IPPD = new_ippd;
ippd = IPPD;
ARRAYSIZE = (MAXPAGES * IPPD) + 50;
return 0;
}
int loadClutter(char *filename, double radius, struct site tx)
{
@@ -291,7 +363,7 @@ int loadLIDAR(char *filenames)
return errno;
fseek(fd, tiles[indx].datastart, SEEK_SET);
if (debug)
fprintf(stderr, "readLIDAR(fd,%d,%d,%d,%.4f,%.4f,%.4f,%.4f)\n", height, width, indx, yur, xur, yll, xll);
fprintf(stderr, "readLIDAR(fd,%d,%d,%d,%.4f,%.4f,%.4f,%.4f)\n", tiles[indx].height, tiles[indx].width, indx, tiles[indx].yur, tiles[indx].xur, tiles[indx].yll, tiles[indx].xll);
readLIDAR(fd, tiles[indx].height, tiles[indx].width, indx, tiles[indx].yur, tiles[indx].xur, tiles[indx].yll, tiles[indx].xll);
}