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flightgear/Tools/Lib/DEM/dem.cxx

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// dem.cxx -- DEM management class
//
// Written by Curtis Olson, started March 1998.
//
// Copyright (C) 1998 Curtis L. Olson - curt@flightgear.org
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <Include/compiler.h>
#include <ctype.h> // isspace()
#include <stdlib.h> // atoi()
#include <math.h> // rint()
#include <stdio.h>
#include <string.h>
#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h> // stat()
#endif
#ifdef FG_HAVE_STD_INCLUDES
# include <cerrno>
#else
# include <errno.h>
#endif
#ifdef HAVE_UNISTD_H
# include <unistd.h> // stat()
#endif
#include <Misc/fgstream.hxx>
#include <Misc/strutils.hxx>
#include <Include/fg_constants.h>
#include "dem.hxx"
#define MAX_EX_NODES 10000
#if 0
#ifdef WIN32
# ifdef __BORLANDC__
# include <dir.h>
# define MKDIR(a) mkdir(a)
# else
# define MKDIR(a) mkdir(a,S_IRWXU) // I am just guessing at this flag (NHV)
# endif // __BORLANDC__
#endif // WIN32
#endif //0
FGDem::FGDem( void ) {
// cout << "class FGDem CONstructor called." << endl;
dem_data = new float[DEM_SIZE_1][DEM_SIZE_1];
output_data = new float[DEM_SIZE_1][DEM_SIZE_1];
}
FGDem::FGDem( const string &file ) {
// cout << "class FGDem CONstructor called." << endl;
dem_data = new float[DEM_SIZE_1][DEM_SIZE_1];
output_data = new float[DEM_SIZE_1][DEM_SIZE_1];
FGDem::open(file);
}
// open a DEM file
int
FGDem::open ( const string& file ) {
// open input file (or read from stdin)
if ( file == "-" ) {
printf("Loading DEM data file: stdin\n");
// fd = stdin;
// fd = gzdopen(STDIN_FILENO, "r");
printf("Not yet ported ...\n");
return 0;
} else {
in = new fg_gzifstream( file );
if ( !(*in) ) {
cout << "Cannot open " << file << endl;
return 0;
}
cout << "Loading DEM data file: " << file << endl;
}
return 1;
}
// close a DEM file
int
FGDem::close () {
// the fg_gzifstream doesn't seem to have a close()
delete in;
return 1;
}
// return next token from input stream
string
FGDem::next_token() {
string token;
*in >> token;
// cout << " returning " + token + "\n";
return token;
}
// return next integer from input stream
int
FGDem::next_int() {
int result;
*in >> result;
return result;
}
// return next double from input stream
double
FGDem::next_double() {
double result;
*in >> result;
return result;
}
// return next exponential num from input stream
double
FGDem::next_exp() {
string token;
token = next_token();
const char* p = token.c_str();
char buf[64];
char* bp = buf;
for ( ; *p != 0; ++p )
{
if ( *p == 'D' )
*bp++ = 'E';
else
*bp++ = *p;
}
*bp = 0;
return ::atof( buf );
}
// read and parse DEM "A" record
int
FGDem::read_a_record() {
int i, inum;
double dnum;
string name, token;
char c;
// get the name field (144 characters)
for ( i = 0; i < 144; i++ ) {
in->get(c);
name += c;
}
// clean off the trailing whitespace
name = trim(name);
cout << " Quad name field: " << name << endl;
// DEM level code, 3 reflects processing by DMA
inum = next_int();
cout << " DEM level code = " << inum << "\n";
if ( inum > 3 ) {
return 0;
}
// Pattern code, 1 indicates a regular elevation pattern
inum = next_int();
cout << " Pattern code = " << inum << "\n";
// Planimetric reference system code, 0 indicates geographic
// coordinate system.
inum = next_int();
cout << " Planimetric reference code = " << inum << "\n";
// Zone code
inum = next_int();
cout << " Zone code = " << inum << "\n";
// Map projection parameters (ignored)
for ( i = 0; i < 15; i++ ) {
dnum = next_exp();
// printf("%d: %f\n",i,dnum);
}
// Units code, 3 represents arc-seconds as the unit of measure for
// ground planimetric coordinates throughout the file.
inum = next_int();
if ( inum != 3 ) {
cout << " Unknown (X,Y) units code = " << inum << "!\n";
exit(-1);
}
// Units code; 2 represents meters as the unit of measure for
// elevation coordinates throughout the file.
inum = next_int();
if ( inum != 2 ) {
cout << " Unknown (Z) units code = " << inum << "!\n";
exit(-1);
}
// Number (n) of sides in the polygon which defines the coverage of
// the DEM file (usually equal to 4).
inum = next_int();
if ( inum != 4 ) {
cout << " Unknown polygon dimension = " << inum << "!\n";
exit(-1);
}
// Ground coordinates of bounding box in arc-seconds
dem_x1 = originx = next_exp();
dem_y1 = originy = next_exp();
cout << " Origin = (" << originx << "," << originy << ")\n";
dem_x2 = next_exp();
dem_y2 = next_exp();
dem_x3 = next_exp();
dem_y3 = next_exp();
dem_x4 = next_exp();
dem_y4 = next_exp();
// Minimum/maximum elevations in meters
dem_z1 = next_exp();
dem_z2 = next_exp();
cout << " Elevation range " << dem_z1 << " to " << dem_z2 << "\n";
// Counterclockwise angle from the primary axis of ground
// planimetric referenced to the primary axis of the DEM local
// reference system.
token = next_token();
// Accuracy code; 0 indicates that a record of accuracy does not
// exist and that no record type C will follow.
// DEM spacial resolution. Usually (3,3,1) (3,6,1) or (3,9,1)
// depending on latitude
// I will eventually have to do something with this for data at
// higher latitudes */
token = next_token();
cout << " accuracy & spacial resolution string = " << token << endl;
i = token.length();
cout << " length = " << i << "\n";
inum = atoi( token.substr( 0, i - 36 ) );
row_step = atof( token.substr( i - 24, 12 ) );
col_step = atof( token.substr( i - 36, 12 ) );
cout << " Accuracy code = " << inum << "\n";
cout << " column step = " << col_step <<
" row step = " << row_step << "\n";
// dimension of arrays to follow (1)
token = next_token();
// number of profiles
dem_num_profiles = cols = next_int();
cout << " Expecting " << dem_num_profiles << " profiles\n";
return 1;
}
// read and parse DEM "B" record
void
FGDem::read_b_record( ) {
string token;
int i;
int last;
// row / column id of this profile
prof_row = next_int();
prof_col = next_int();
// printf("col id = %d row id = %d\n", prof_col, prof_row);
// Number of columns and rows (elevations) in this profile
prof_num_rows = rows = next_int();
prof_num_cols = next_int();
// printf(" profile num rows = %d\n", prof_num_rows);
// Ground planimetric coordinates (arc-seconds) of the first
// elevation in the profile
prof_x1 = next_exp();
prof_y1 = next_exp();
// printf(" Starting at %.2f %.2f\n", prof_x1, prof_y1);
// Elevation of local datum for the profile. Always zero for
// 1-degree DEM, the reference is mean sea level.
token = next_token();
// Minimum and maximum elevations for the profile.
token = next_token();
token = next_token();
// One (usually) dimensional array (prof_num_cols,1) of elevations
last = 0;
for ( i = 0; i < prof_num_rows; i++ ) {
prof_data = next_int();
// a bit of sanity checking that is unfortunately necessary
if ( prof_data > 10000 ) { // meters
prof_data = last;
}
dem_data[cur_col][i] = (float)prof_data;
last = prof_data;
}
}
// parse dem file
int
FGDem::parse( ) {
int i;
cur_col = 0;
if ( !read_a_record() ) {
return(0);
}
for ( i = 0; i < dem_num_profiles; i++ ) {
// printf("Ready to read next b record\n");
read_b_record();
cur_col++;
if ( cur_col % 100 == 0 ) {
cout << " loaded " << cur_col << " profiles of data\n";
}
}
cout << " Done parsing\n";
return 1;
}
// write out the area of data covered by the specified bucket. Data
// is written out column by column starting at the lower left hand
// corner.
int
FGDem::write_area( const string& root, FGBucket& b, bool compress ) {
// calculate some boundaries
double min_x = ( b.get_center_lon() - 0.5 * b.get_width() ) * 3600.0;
double max_x = ( b.get_center_lon() + 0.5 * b.get_width() ) * 3600.0;
double min_y = ( b.get_center_lat() - 0.5 * b.get_height() ) * 3600.0;
double max_y = ( b.get_center_lat() + 0.5 * b.get_height() ) * 3600.0;
cout << b << endl;
cout << "width = " << b.get_width() << " height = " << b.get_height()
<< endl;
int start_x = (int)((min_x - originx) / col_step);
int span_x = (int)(b.get_width() * 3600.0 / col_step);
int start_y = (int)((min_y - originy) / row_step);
int span_y = (int)(b.get_height() * 3600.0 / row_step);
cout << "start_x = " << start_x << " span_x = " << span_x << endl;
cout << "start_y = " << start_y << " span_y = " << span_y << endl;
// Do a simple sanity checking. But, please, please be nice to
// this write_area() routine and feed it buckets that coincide
// well with the underlying grid structure and spacing.
if ( ( min_x < originx )
|| ( max_x > originx + cols * col_step )
|| ( min_y < originy )
|| ( max_y > originy + rows * row_step ) ) {
cout << " ERROR: bucket at least partially outside DEM data range!" <<
endl;
return 0;
}
// generate output file name
string base = b.gen_base_path();
string path = root + "/Scenery/" + base;
string command = "mkdir -p " + path;
system( command.c_str() );
string demfile = path + "/" + b.gen_index_str() + ".dem";
cout << "demfile = " << demfile << endl;
// write the file
FILE *fp;
if ( (fp = fopen(demfile.c_str(), "w")) == NULL ) {
cout << "cannot open " << demfile << " for writing!" << endl;
exit(-1);
}
fprintf( fp, "%d %d\n", (int)min_x, (int)min_y );
fprintf( fp, "%d %d %d %d\n", span_x + 1, (int)col_step,
span_y + 1, (int)row_step );
for ( int i = start_x; i <= start_x + span_x; ++i ) {
for ( int j = start_y; j <= start_y + span_y; ++j ) {
fprintf( fp, "%d ", (int)dem_data[i][j] );
}
fprintf( fp, "\n" );
}
fclose(fp);
if ( compress ) {
string command = "gzip --best -f " + demfile;
system( command.c_str() );
}
return 1;
}
#if 0
// return the current altitude based on grid data. We should rewrite
// this to interpolate exact values, but for now this is good enough
double FGDem::interpolate_altitude( double lon, double lat ) {
// we expect incoming (lon,lat) to be in arcsec for now
double xlocal, ylocal, dx, dy, zA, zB, elev;
int x1, x2, x3, y1, y2, y3;
float z1, z2, z3;
int xindex, yindex;
/* determine if we are in the lower triangle or the upper triangle
______
| /|
| / |
| / |
|/ |
------
then calculate our end points
*/
xlocal = (lon - originx) / col_step;
ylocal = (lat - originy) / row_step;
xindex = (int)(xlocal);
yindex = (int)(ylocal);
// printf("xindex = %d yindex = %d\n", xindex, yindex);
if ( xindex + 1 == cols ) {
xindex--;
}
if ( yindex + 1 == rows ) {
yindex--;
}
if ( (xindex < 0) || (xindex + 1 >= cols) ||
(yindex < 0) || (yindex + 1 >= rows) ) {
return(-9999);
}
dx = xlocal - xindex;
dy = ylocal - yindex;
if ( dx > dy ) {
// lower triangle
// printf(" Lower triangle\n");
x1 = xindex;
y1 = yindex;
z1 = dem_data[x1][y1];
x2 = xindex + 1;
y2 = yindex;
z2 = dem_data[x2][y2];
x3 = xindex + 1;
y3 = yindex + 1;
z3 = dem_data[x3][y3];
// printf(" dx = %.2f dy = %.2f\n", dx, dy);
// printf(" (x1,y1,z1) = (%d,%d,%d)\n", x1, y1, z1);
// printf(" (x2,y2,z2) = (%d,%d,%d)\n", x2, y2, z2);
// printf(" (x3,y3,z3) = (%d,%d,%d)\n", x3, y3, z3);
zA = dx * (z2 - z1) + z1;
zB = dx * (z3 - z1) + z1;
// printf(" zA = %.2f zB = %.2f\n", zA, zB);
if ( dx > FG_EPSILON ) {
elev = dy * (zB - zA) / dx + zA;
} else {
elev = zA;
}
} else {
// upper triangle
// printf(" Upper triangle\n");
x1 = xindex;
y1 = yindex;
z1 = dem_data[x1][y1];
x2 = xindex;
y2 = yindex + 1;
z2 = dem_data[x2][y2];
x3 = xindex + 1;
y3 = yindex + 1;
z3 = dem_data[x3][y3];
// printf(" dx = %.2f dy = %.2f\n", dx, dy);
// printf(" (x1,y1,z1) = (%d,%d,%d)\n", x1, y1, z1);
// printf(" (x2,y2,z2) = (%d,%d,%d)\n", x2, y2, z2);
// printf(" (x3,y3,z3) = (%d,%d,%d)\n", x3, y3, z3);
zA = dy * (z2 - z1) + z1;
zB = dy * (z3 - z1) + z1;
// printf(" zA = %.2f zB = %.2f\n", zA, zB );
// printf(" xB - xA = %.2f\n", col_step * dy / row_step);
if ( dy > FG_EPSILON ) {
elev = dx * (zB - zA) / dy + zA;
} else {
elev = zA;
}
}
return(elev);
}
// Use least squares to fit a simpler data set to dem data
void FGDem::fit( double error, FGBucket& p ) {
double x[DEM_SIZE_1], y[DEM_SIZE_1];
double m, b, ave_error, max_error;
double cury, lasty;
int n, row, start, end;
int colmin, colmax, rowmin, rowmax;
bool good_fit;
// FILE *dem, *fit, *fit1;
printf("Initializing output mesh structure\n");
outputmesh_init();
// determine dimensions
colmin = p.get_x() * ( (cols - 1) / 8);
colmax = colmin + ( (cols - 1) / 8);
rowmin = p.get_y() * ( (rows - 1) / 8);
rowmax = rowmin + ( (rows - 1) / 8);
printf("Fitting region = %d,%d to %d,%d\n", colmin, rowmin, colmax, rowmax);
// include the corners explicitly
outputmesh_set_pt(colmin, rowmin, dem_data[colmin][rowmin]);
outputmesh_set_pt(colmin, rowmax, dem_data[colmin][rowmax]);
outputmesh_set_pt(colmax, rowmax, dem_data[colmax][rowmax]);
outputmesh_set_pt(colmax, rowmin, dem_data[colmax][rowmin]);
printf("Beginning best fit procedure\n");
for ( row = rowmin; row <= rowmax; row++ ) {
// fit = fopen("fit.dat", "w");
// fit1 = fopen("fit1.dat", "w");
start = colmin;
// printf(" fitting row = %d\n", row);
while ( start < colmax ) {
end = start + 1;
good_fit = true;
x[(end - start) - 1] = 0.0 + ( start * col_step );
y[(end - start) - 1] = dem_data[start][row];
while ( (end <= colmax) && good_fit ) {
n = (end - start) + 1;
// printf("Least square of first %d points\n", n);
x[end - start] = 0.0 + ( end * col_step );
y[end - start] = dem_data[end][row];
least_squares(x, y, n, &m, &b);
ave_error = least_squares_error(x, y, n, m, b);
max_error = least_squares_max_error(x, y, n, m, b);
/*
printf("%d - %d ave error = %.2f max error = %.2f y = %.2f*x + %.2f\n",
start, end, ave_error, max_error, m, b);
f = fopen("gnuplot.dat", "w");
for ( j = 0; j <= end; j++) {
fprintf(f, "%.2f %.2f\n", 0.0 + ( j * col_step ),
dem_data[row][j]);
}
for ( j = start; j <= end; j++) {
fprintf(f, "%.2f %.2f\n", 0.0 + ( j * col_step ),
dem_data[row][j]);
}
fclose(f);
printf("Please hit return: "); gets(junk);
*/
if ( max_error > error ) {
good_fit = false;
}
end++;
}
if ( !good_fit ) {
// error exceeded the threshold, back up
end -= 2; // back "end" up to the last good enough fit
n--; // back "n" up appropriately too
} else {
// we popped out of the above loop while still within
// the error threshold, so we must be at the end of
// the data set
end--;
}
least_squares(x, y, n, &m, &b);
ave_error = least_squares_error(x, y, n, m, b);
max_error = least_squares_max_error(x, y, n, m, b);
/*
printf("\n");
printf("%d - %d ave error = %.2f max error = %.2f y = %.2f*x + %.2f\n",
start, end, ave_error, max_error, m, b);
printf("\n");
fprintf(fit1, "%.2f %.2f\n", x[0], m * x[0] + b);
fprintf(fit1, "%.2f %.2f\n", x[end-start], m * x[end-start] + b);
*/
if ( start > colmin ) {
// skip this for the first line segment
cury = m * x[0] + b;
outputmesh_set_pt(start, row, (lasty + cury) / 2);
// fprintf(fit, "%.2f %.2f\n", x[0], (lasty + cury) / 2);
}
lasty = m * x[end-start] + b;
start = end;
}
/*
fclose(fit);
fclose(fit1);
dem = fopen("gnuplot.dat", "w");
for ( j = 0; j < DEM_SIZE_1; j++) {
fprintf(dem, "%.2f %.2f\n", 0.0 + ( j * col_step ),
dem_data[j][row]);
}
fclose(dem);
*/
// NOTICE, this is for testing only. This instance of
// output_nodes should be removed. It should be called only
// once at the end once all the nodes have been generated.
// newmesh_output_nodes(&nm, "mesh.node");
// printf("Please hit return: "); gets(junk);
}
// outputmesh_output_nodes(fg_root, p);
}
// Initialize output mesh structure
void FGDem::outputmesh_init( void ) {
int i, j;
for ( j = 0; j < DEM_SIZE_1; j++ ) {
for ( i = 0; i < DEM_SIZE_1; i++ ) {
output_data[i][j] = -9999.0;
}
}
}
// Get the value of a mesh node
double FGDem::outputmesh_get_pt( int i, int j ) {
return ( output_data[i][j] );
}
// Set the value of a mesh node
void FGDem::outputmesh_set_pt( int i, int j, double value ) {
// printf("Setting data[%d][%d] = %.2f\n", i, j, value);
output_data[i][j] = value;
}
// Write out a node file that can be used by the "triangle" program.
// Check for an optional "index.node.ex" file in case there is a .poly
// file to go along with this node file. Include these nodes first
// since they are referenced by position from the .poly file.
void FGDem::outputmesh_output_nodes( const string& fg_root, FGBucket& p )
{
double exnodes[MAX_EX_NODES][3];
struct stat stat_buf;
string dir;
char file[256], exfile[256];
#ifdef WIN32
char tmp_path[256];
#endif
string command;
FILE *fd;
long int index;
int colmin, colmax, rowmin, rowmax;
int i, j, count, excount, result;
// determine dimensions
colmin = p.get_x() * ( (cols - 1) / 8);
colmax = colmin + ( (cols - 1) / 8);
rowmin = p.get_y() * ( (rows - 1) / 8);
rowmax = rowmin + ( (rows - 1) / 8);
cout << " dumping region = " << colmin << "," << rowmin << " to " <<
colmax << "," << rowmax << "\n";
// generate the base directory
string base_path = p.gen_base_path();
cout << "fg_root = " << fg_root << " Base Path = " << base_path << endl;
dir = fg_root + "/Scenery/" + base_path;
cout << "Dir = " << dir << endl;
// stat() directory and create if needed
errno = 0;
result = stat(dir.c_str(), &stat_buf);
if ( result != 0 && errno == ENOENT ) {
cout << "Creating directory\n";
// #ifndef WIN32
command = "mkdir -p " + dir + "\n";
system( command.c_str() );
#if 0
// #else // WIN32
// Cygwin crashes when trying to output to node file
// explicitly making directory structure seems OK on Win95
extract_path (base_path, tmp_path);
dir = fg_root + "/Scenery";
if (my_mkdir ( dir.c_str() )) { exit (-1); }
dir = fg_root + "/Scenery/" + tmp_path;
if (my_mkdir ( dir.c_str() )) { exit (-1); }
dir = fg_root + "/Scenery/" + base_path;
if (my_mkdir ( dir.c_str() )) { exit (-1); }
// #endif // WIN32
#endif //0
} else {
// assume directory exists
}
// get index and generate output file name
index = p.gen_index();
sprintf(file, "%s/%ld.node", dir.c_str(), index);
// get (optional) extra node file name (in case there is matching
// .poly file.
strcpy(exfile, file);
strcat(exfile, ".ex");
// load extra nodes if they exist
excount = 0;
if ( (fd = fopen(exfile, "r")) != NULL ) {
int junki;
fscanf(fd, "%d %d %d %d", &excount, &junki, &junki, &junki);
if ( excount > MAX_EX_NODES - 1 ) {
printf("Error, too many 'extra' nodes, increase array size\n");
exit(-1);
} else {
printf(" Expecting %d 'extra' nodes\n", excount);
}
for ( i = 1; i <= excount; i++ ) {
fscanf(fd, "%d %lf %lf %lf\n", &junki,
&exnodes[i][0], &exnodes[i][1], &exnodes[i][2]);
printf("(extra) %d %.2f %.2f %.2f\n",
i, exnodes[i][0], exnodes[i][1], exnodes[i][2]);
}
fclose(fd);
}
printf("Creating node file: %s\n", file);
fd = fopen(file, "w");
// first count regular nodes to generate header
count = 0;
for ( j = rowmin; j <= rowmax; j++ ) {
for ( i = colmin; i <= colmax; i++ ) {
if ( output_data[i][j] > -9000.0 ) {
count++;
}
}
// printf(" count = %d\n", count);
}
fprintf(fd, "%d 2 1 0\n", count + excount);
// now write out extra node data
for ( i = 1; i <= excount; i++ ) {
fprintf(fd, "%d %.2f %.2f %.2f\n",
i, exnodes[i][0], exnodes[i][1], exnodes[i][2]);
}
// write out actual node data
count = excount + 1;
for ( j = rowmin; j <= rowmax; j++ ) {
for ( i = colmin; i <= colmax; i++ ) {
if ( output_data[i][j] > -9000.0 ) {
fprintf(fd, "%d %.2f %.2f %.2f\n",
count++,
originx + (double)i * col_step,
originy + (double)j * row_step,
output_data[i][j]);
}
}
// printf(" count = %d\n", count);
}
fclose(fd);
}
#endif
FGDem::~FGDem( void ) {
// printf("class FGDem DEstructor called.\n");
delete [] dem_data;
delete [] output_data;
}
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