Initial revision (with data skipping support)
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298
Scenery/dem2scene.pl
Executable file
298
Scenery/dem2scene.pl
Executable file
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#!/usr/local/bin/perl
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#
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# dem2scene.pl -- Read in a dem data file, and output a more usable format.
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#
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# Written by Curtis Olson, started May 1997.
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#
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# Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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#
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# $Id$
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# (Log is kept at end of this file)
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#---------------------------------------------------------------------------
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use strict;
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# declare variables
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my($token);
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my($i, $j);
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my($arg);
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my($res) = 1;
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# "A" Record Information
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my($dem_description, $dem_quadrangle);
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my($dem_x1, $dem_y1, $dem_x2, $dem_y2, $dem_x3, $dem_y3, $dem_x4, $dem_y4);
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my($dem_z1, $dem_z2);
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my($dem_resolution, $dem_num_profiles);
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# "B" Record Information
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my($prof_row, $prof_col);
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my($prof_num_rows, $prof_num_cols);
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my($prof_x1, $prof_y1);
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my($prof_data);
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# set input record separator to be a space
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$/ = " ";
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# parse command line arguments
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while ( $arg = shift(@ARGV) ) {
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if ( $arg eq "-r" ) {
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$res = shift(@ARGV);
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if ( $res < 1 ) {
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&usage();
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}
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} else {
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&usage();
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}
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}
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# print usage and die
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sub usage {
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die "Usage: $0 [ -r resval ]\n";
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}
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&read_a_record();
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&output_scene_hdr();
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$i = 0;
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while ( $i < $dem_num_profiles ) {
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&read_b_record();
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&output_row();
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$i++;
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if ( $i < $dem_num_profiles ) {
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# not on last record
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for ( $j = 1; $j < $res; $j++ ) {
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# print "skipping row\n";
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&read_b_record();
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}
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}
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}
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&output_scene_close();
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# read and parse DEM "A" record
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sub read_a_record {
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my($i);
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# read initial descriptive header
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while ( ($token = &next_token()) ne "_END_OF_FILE_" ) {
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if ( $token !~ m/^NJ/ && $token !~ m/^NI/ ) {
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$dem_description .= "$token ";
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} else {
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chop($dem_description);
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$dem_quadrangle = $token;
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last;
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}
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}
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# print "'$dem_description' '$dem_quadrangle'\n";
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# DEM level code, 3 reflects processing by DMA
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&next_token();
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# Pattern code, 1 indicates a regular elevation pattern
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&next_token();
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# Planimetric reference system code, 0 indicates geographic
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# coordinate system.
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&next_token();
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# Zone code
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&next_token();
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# Map projection parameters (ignored)
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for ($i = 0; $i < 15; $i++) {
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&next_token();
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}
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# Units code, 3 represents arc-seconds as the unit of measure for
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# ground planimetric coordinates throughout the file.
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die "Unknown units code!\n" if ( &next_token() ne "3" );
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# Units code; 2 represents meters as the unit of measure for
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# elevation coordinates throughout the file.
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die "Unknown units code!\n" if ( &next_token() ne "2" );
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# Number (n) of sides in the polygon which defines the coverage of
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# the DEM file (usually equal to 4).
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die "Unknown polygon dimension!\n" if ( &next_token() ne "4" );
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# Ground coordinates of bounding box in arc-seconds
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$dem_x1 = &next_token();
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$dem_y1 = &next_token();
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$dem_x2 = &next_token();
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$dem_y2 = &next_token();
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$dem_x3 = &next_token();
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$dem_y3 = &next_token();
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$dem_x4 = &next_token();
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$dem_y4 = &next_token();
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# Minimum/maximum elevations in meters
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$dem_z1 = &next_token();
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$dem_z2 = &next_token();
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# Counterclockwise angle from the primary axis of ground
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# planimetric referenced to the primary axis of the DEM local
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# reference system.
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&next_token();
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# Accuracy code; 0 indicates that a record of accuracy does not
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# exist and that no record type C will follow.
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# &next_token();
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# DEM spacial resolution. Usually (3,3,1) (3,6,1) or (3,9,1)
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# depending on latitude
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$dem_resolution = &next_token();
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# one dimensional arrays
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&next_token();
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# number of profiles
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$dem_num_profiles = &next_token();
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$dem_num_profiles = (($dem_num_profiles - 1) / $res) + 1;
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}
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# output the scene headers
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sub output_scene_hdr {
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my($dx, $dy, $dz);
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printf("mesh %s_terrain {\n", $dem_quadrangle);
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$dem_x1 =~ s/D/E/; $dem_x1 += 0.0;
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$dem_y1 =~ s/D/E/; $dem_y1 += 0.0;
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print " // This mesh is rooted at the following coordinates (in arc seconds)\n";
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print " origin_lat = $dem_x1\n";
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print " origin_lon = $dem_y1\n";
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print "\n";
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print " // Number of rows and columns (needed by the parser so it can create\n";
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print " //the proper size structure\n";
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print " rows = $dem_num_profiles\n";
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print " cols = $dem_num_profiles\n"; # This isn't necessarily guaranteed
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print "\n";
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($dx, $dy, $dz) = $dem_resolution =~
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m/(.............)(............)(............)/;
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$dx *= $res;
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$dy *= $res;
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print " // Distance between x and y data points (in arc seconds)\n";
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print " row_step = $dx\n";
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print " col_step = $dy\n";
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print "\n";
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}
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# output the scene close
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sub output_scene_close {
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print "\n";
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print "}\n";
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}
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# read and parse DEM "B" record
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sub read_b_record {
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my($i, $j);
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# row / column id of this profile
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$prof_row = &next_token();
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$prof_col = &next_token();
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# Number of rows (elevations) and columns in this profile;
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$prof_num_rows = &next_token();
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$prof_num_cols = &next_token();
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$prof_num_rows = (($prof_num_rows - 1) / $res) + 1;
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# print "profile num rows = $prof_num_rows\n";
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# Ground planimetric coordinates (arc-seconds) of the first
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# elevation in the profile
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$prof_x1 = &next_token();
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$prof_y1 = &next_token();
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# Elevation of local datum for the profile. Always zero for
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# 1-degree DEM, the reference is mean sea level.
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&next_token();
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# Minimum and maximum elevations for the profile.
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&next_token();
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&next_token();
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# One (usually) dimensional array ($prof_num_rows,1) of elevations
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$prof_data = "";
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$i = 0;
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while ( $i < $prof_num_rows ) {
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$prof_data .= &next_token();
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$prof_data .= " ";
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$i++;
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if ( $i < $prof_num_rows ) {
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# not on last data point
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# skip the tokens to get requested resolution
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for ($j = 1; $j < $res; $j++) {
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# print "skipping ...\n";
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&next_token();
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}
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}
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}
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chop($prof_data);
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# print "$prof_data\n\n";
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}
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# output a row of data
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sub output_row {
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print " row = ($prof_data)\n";
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}
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# return next token from input stream
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sub next_token {
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my($token);
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# print "in next token\n";
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do {
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$token = <>; chop($token);
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if ( eof() ) {
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$token = "_END_OF_FILE_";
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}
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} while ( $token eq "" );
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# print "returning $token\n";
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return $token;
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}
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while ( ($token = &next_token()) ne "_END_OF_FILE_" ) {
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# print "'$token'\n";
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}
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#---------------------------------------------------------------------------
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# $Log$
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# Revision 1.1 1997/05/27 21:56:02 curt
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# Initial revision (with data skipping support)
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#
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