fly/flightgear
1
0
Fork 0
Code Activity
flightgear/DEM/dem.c

693 lines
17 KiB
C
Raw Blame History

// -*- Mode: C++ -*-
//
// dem.c -- DEM management class
//
// Written by Curtis Olson, started March 1998.
//
// Copyright (C) 1998 Curtis L. Olson - curt@me.umn.edu
//
// 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.
//
// $Id$
// (Log is kept at end of this file)
#include <ctype.h> // isspace()
#include <math.h> // rint()
#include <stdio.h>
#include <stdlib.h> // atoi()
#include <sys/stat.h> // stat()
#include <unistd.h> // stat()
#include "dem.h"
#include "leastsqs.h"
fgDEM::fgDEM( void ) {
// printf("class fgDEM CONstructor called.\n");
}
// open a DEM file
int fgDEM::open ( char *file ) {
// open input file (or read from stdin)
if ( strcmp(file, "-") == 0 ) {
printf("Loading DEM data file: stdin\n");
fd = stdin;
} else {
if ( (fd = fopen(file, "r")) == NULL ) {
printf("Cannot open %s\n", file);
return(0);
}
printf("Loading DEM data file: %s\n", file);
}
return(1);
}
// close a DEM file
int fgDEM::close ( void ) {
fclose(fd);
return(1);
}
// return next token from input stream
static void next_token(FILE *fd, char *token) {
int result;
result = fscanf(fd, "%s", token);
if ( result == EOF ) {
strcpy(token, "__END_OF_FILE__");
printf(" Warning: Reached end of file!\n");
}
// printf(" returning %s\n", token);
}
// return next integer from input stream
static int next_int(FILE *fd) {
char token[80];
next_token(fd, token);
return ( atoi(token) );
}
// return next double from input stream
double next_double(FILE *fd) {
char token[80];
next_token(fd, token);
return ( atof(token) );
}
// return next exponential num from input stream
int next_exp(FILE *fd) {
double mantissa;
int exp, acc;
int i;
fscanf(fd, "%lfD%d", &mantissa, &exp);
// printf(" Mantissa = %.4f Exp = %d\n", mantissa, exp);
acc = 1;
if ( exp > 0 ) {
for ( i = 1; i <= exp; i++ ) {
acc *= 10;
}
} else if ( exp < 0 ) {
for ( i = -1; i >= exp; i-- ) {
acc /= 10;
}
}
return( (int)rint(mantissa * (double)acc) );
}
// read and parse DEM "A" record
void fgDEM::read_a_record( void ) {
int i, inum;
double dnum;
char name[144];
char token[80];
char *ptr;
// get the name field (144 characters)
for ( i = 0; i < 144; i++ ) {
name[i] = fgetc(fd);
}
name[i+1] = '\0';
// clean off the whitespace at the end
for ( i = strlen(name)-2; i > 0; i-- ) {
if ( !isspace(name[i]) ) {
i=0;
} else {
name[i] = '\0';
}
}
printf(" Quad name field: %s\n", name);
// DEM level code, 3 reflects processing by DMA
inum = next_int(fd);
printf(" DEM level code = %d\n", inum);
// Pattern code, 1 indicates a regular elevation pattern
inum = next_int(fd);
printf(" Pattern code = %d\n", inum);
// Planimetric reference system code, 0 indicates geographic
// coordinate system.
inum = next_int(fd);
printf(" Planimetric reference code = %d\n", inum);
// Zone code
inum = next_int(fd);
printf(" Zone code = %d\n", inum);
// Map projection parameters (ignored)
for ( i = 0; i < 15; i++ ) {
dnum = next_double(fd);
// 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(fd);
if ( inum != 3 ) {
printf(" Unknown (X,Y) units code = %d!\n", inum);
exit(-1);
}
// Units code; 2 represents meters as the unit of measure for
// elevation coordinates throughout the file.
inum = next_int(fd);
if ( inum != 2 ) {
printf(" Unknown (Z) units code = %d!\n", inum);
exit(-1);
}
// Number (n) of sides in the polygon which defines the coverage of
// the DEM file (usually equal to 4).
inum = next_int(fd);
if ( inum != 4 ) {
printf(" Unknown polygon dimension = %d!\n", inum);
exit(-1);
}
// Ground coordinates of bounding box in arc-seconds
dem_x1 = originx = next_exp(fd);
dem_y1 = originy = next_exp(fd);
printf(" Origin = (%.2f,%.2f)\n", originx, originy);
dem_x2 = next_exp(fd);
dem_y2 = next_exp(fd);
dem_x3 = next_exp(fd);
dem_y3 = next_exp(fd);
dem_x4 = next_exp(fd);
dem_y4 = next_exp(fd);
// Minimum/maximum elevations in meters
dem_z1 = next_exp(fd);
dem_z2 = next_exp(fd);
printf(" Elevation range %.4f %.4f\n", dem_z1, dem_z2);
// Counterclockwise angle from the primary axis of ground
// planimetric referenced to the primary axis of the DEM local
// reference system.
next_token(fd, 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 */
next_token(fd, token);
printf(" accuracy & spacial resolution string = %s\n", token);
i = strlen(token);
printf(" length = %d\n", i);
ptr = token + i - 12;
printf(" last field = %s = %.2f\n", ptr, atof(ptr));
ptr[0] = '\0';
ptr = ptr - 12;
col_step = atof(ptr);
printf(" last field = %s = %.2f\n", ptr, col_step);
ptr[0] = '\0';
ptr = ptr - 12;
row_step = atof(ptr);
printf(" last field = %s = %.2f\n", ptr, row_step);
ptr[0] = '\0';
// accuracy code = atod(token)
inum = atoi(token);
printf(" Accuracy code = %d\n", inum);
printf(" column step = %.2f row step = %.2f\n",
col_step, row_step);
// dimension of arrays to follow (1)
next_token(fd, token);
// number of profiles
dem_num_profiles = rows = next_int(fd);
printf(" Expecting %d profiles\n", dem_num_profiles);
}
// read and parse DEM "B" record
void fgDEM::read_b_record(float dem_data[DEM_SIZE_1][DEM_SIZE_1])
{
char token[80];
int i;
// row / column id of this profile
prof_col = next_int(fd);
prof_row = next_int(fd);
// printf("col id = %d row id = %d\n", prof_col, prof_row);
// Number of columns and rows (elevations) in this profile
prof_num_cols = cols = next_int(fd);
prof_num_rows = next_int(fd);
// printf(" profile num rows = %d\n", prof_num_cols);
// Ground planimetric coordinates (arc-seconds) of the first
// elevation in the profile
prof_x1 = next_exp(fd);
prof_y1 = next_exp(fd);
// 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.
next_token(fd, token);
// Minimum and maximum elevations for the profile.
next_token(fd, token);
next_token(fd, token);
// One (usually) dimensional array (prof_num_cols,1) of elevations
for ( i = 0; i < prof_num_cols; i++ ) {
prof_data = next_int(fd);
dem_data[i][cur_row] = (float)prof_data;
}
}
// parse dem file
int fgDEM::parse( float dem_data[DEM_SIZE_1][DEM_SIZE_1] ) {
int i;
cur_row = 0;
read_a_record();
for ( i = 0; i < dem_num_profiles; i++ ) {
read_b_record( dem_data );
cur_row++;
if ( cur_row % 100 == 0 ) {
printf(" loaded %d profiles of data\n", cur_row);
}
}
printf(" Done parsing\n");
return(0);
}
// return the current altitude based on mesh data. We should rewrite
// this to interpolate exact values, but for now this is good enough
double fgDEM::interpolate_altitude( float dem_data[DEM_SIZE_1][DEM_SIZE_1],
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 > 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 > 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( float dem_data[DEM_SIZE_1][DEM_SIZE_1],
float output_data[DEM_SIZE_1][DEM_SIZE_1],
char *fg_root, double error, struct 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, good_fit;
int colmin, colmax, rowmin, rowmax;
// FILE *dem, *fit, *fit1;
printf("Initializing output mesh structure\n");
outputmesh_init( output_data );
// determine dimensions
colmin = p->x * ( (cols - 1) / 8);
colmax = colmin + ( (cols - 1) / 8);
rowmin = p->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(output_data, colmin, rowmin, dem_data[colmin][rowmin]);
outputmesh_set_pt(output_data, colmin, rowmax, dem_data[colmin][rowmax]);
outputmesh_set_pt(output_data, colmax, rowmax, dem_data[colmax][rowmax]);
outputmesh_set_pt(output_data, 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 = 1;
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 = 0;
}
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(output_data, 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(output_data, fg_root, p);
}
// Initialize output mesh structure
void fgDEM::outputmesh_init( float output_data[DEM_SIZE_1][DEM_SIZE_1] ) {
int i, j;
for ( i = 0; i < DEM_SIZE_1; i++ ) {
for ( j = 0; j < DEM_SIZE_1; j++ ) {
output_data[i][j] = -9999.0;
}
}
}
// Get the value of a mesh node
double fgDEM::outputmesh_get_pt( float output_data[DEM_SIZE_1][DEM_SIZE_1],
int i, int j )
{
return ( output_data[i][j] );
}
// Set the value of a mesh node
void fgDEM::outputmesh_set_pt( float output_data[DEM_SIZE_1][DEM_SIZE_1],
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
void fgDEM::outputmesh_output_nodes( float output_data[DEM_SIZE_1][DEM_SIZE_1],
char *fg_root, struct fgBUCKET *p )
{
struct stat stat_buf;
char base_path[256], dir[256], file[256];
char command[256];
FILE *fd;
long int index;
int colmin, colmax, rowmin, rowmax;
int i, j, count, result;
// determine dimensions
colmin = p->x * ( (cols - 1) / 8);
colmax = colmin + ( (cols - 1) / 8);
rowmin = p->y * ( (rows - 1) / 8);
rowmax = rowmin + ( (rows - 1) / 8);
printf(" dumping region = %d,%d to %d,%d\n",
colmin, rowmin, colmax, rowmax);
// generate the base directory
fgBucketGenBasePath(p, base_path);
printf("fg_root = %s Base Path = %s\n", fg_root, base_path);
sprintf(dir, "%s/Scenery/%s", fg_root, base_path);
printf("Dir = %s\n", dir);
// stat() directory and create if needed
result = stat(dir, &stat_buf);
if ( result != 0 ) {
printf("Stat error need to create directory\n");
sprintf(command, "mkdir -p %s\n", dir);
system(command);
} else {
// assume directory exists
}
// get index and generate output file name
index = fgBucketGenIndex(p);
sprintf(file, "%s/%ld.node", dir, index);
printf("Creating node file: %s\n", file);
fd = fopen(file, "w");
// first count 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);
// now write out actual node data
count = 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);
}
fgDEM::~fgDEM( void ) {
// printf("class fgDEM DEstructor called.\n");
}
// $Log$
// Revision 1.1 1998/03/19 02:54:47 curt
// Reorganized into a class lib called fgDEM.
//
// Revision 1.1 1998/03/19 01:46:28 curt
// Initial revision.
//
View git blame Copy permalink