--- /dev/null
+#!/usr/local/bin/perl
+#
+# dem2scene.pl -- Read in a dem data file, and output a more usable format.
+#
+# Written by Curtis Olson, started May 1997.
+#
+# Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
+#
+# 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)
+#---------------------------------------------------------------------------
+
+
+use strict;
+
+
+# declare variables
+my($token);
+my($i, $j);
+my($arg);
+my($res) = 1;
+
+# "A" Record Information
+my($dem_description, $dem_quadrangle);
+my($dem_x1, $dem_y1, $dem_x2, $dem_y2, $dem_x3, $dem_y3, $dem_x4, $dem_y4);
+my($dem_z1, $dem_z2);
+my($dem_resolution, $dem_num_profiles);
+
+# "B" Record Information
+my($prof_row, $prof_col);
+my($prof_num_rows, $prof_num_cols);
+my($prof_x1, $prof_y1);
+my($prof_data);
+
+# set input record separator to be a space
+$/ = " ";
+
+# parse command line arguments
+while ( $arg = shift(@ARGV) ) {
+ if ( $arg eq "-r" ) {
+ $res = shift(@ARGV);
+ if ( $res < 1 ) {
+ &usage();
+ }
+ } else {
+ &usage();
+ }
+}
+
+# print usage and die
+sub usage {
+ die "Usage: $0 [ -r resval ]\n";
+}
+
+
+&read_a_record();
+&output_scene_hdr();
+
+$i = 0;
+while ( $i < $dem_num_profiles ) {
+ &read_b_record();
+ &output_row();
+
+ $i++;
+
+ if ( $i < $dem_num_profiles ) {
+ # not on last record
+ for ( $j = 1; $j < $res; $j++ ) {
+ # print "skipping row\n";
+ &read_b_record();
+ }
+ }
+}
+
+&output_scene_close();
+
+# read and parse DEM "A" record
+sub read_a_record {
+ my($i);
+
+ # read initial descriptive header
+ while ( ($token = &next_token()) ne "_END_OF_FILE_" ) {
+ if ( $token !~ m/^NJ/ && $token !~ m/^NI/ ) {
+ $dem_description .= "$token ";
+ } else {
+ chop($dem_description);
+ $dem_quadrangle = $token;
+ last;
+ }
+ }
+ # print "'$dem_description' '$dem_quadrangle'\n";
+
+ # DEM level code, 3 reflects processing by DMA
+ &next_token();
+
+ # Pattern code, 1 indicates a regular elevation pattern
+ &next_token();
+
+ # Planimetric reference system code, 0 indicates geographic
+ # coordinate system.
+ &next_token();
+
+ # Zone code
+ &next_token();
+
+ # Map projection parameters (ignored)
+ for ($i = 0; $i < 15; $i++) {
+ &next_token();
+ }
+
+ # Units code, 3 represents arc-seconds as the unit of measure for
+ # ground planimetric coordinates throughout the file.
+ die "Unknown units code!\n" if ( &next_token() ne "3" );
+
+ # Units code; 2 represents meters as the unit of measure for
+ # elevation coordinates throughout the file.
+ die "Unknown units code!\n" if ( &next_token() ne "2" );
+
+ # Number (n) of sides in the polygon which defines the coverage of
+ # the DEM file (usually equal to 4).
+ die "Unknown polygon dimension!\n" if ( &next_token() ne "4" );
+
+ # Ground coordinates of bounding box in arc-seconds
+ $dem_x1 = &next_token();
+ $dem_y1 = &next_token();
+
+ $dem_x2 = &next_token();
+ $dem_y2 = &next_token();
+
+ $dem_x3 = &next_token();
+ $dem_y3 = &next_token();
+
+ $dem_x4 = &next_token();
+ $dem_y4 = &next_token();
+
+ # Minimum/maximum elevations in meters
+ $dem_z1 = &next_token();
+ $dem_z2 = &next_token();
+
+ # Counterclockwise angle from the primary axis of ground
+ # planimetric referenced to the primary axis of the DEM local
+ # reference system.
+ &next_token();
+
+ # Accuracy code; 0 indicates that a record of accuracy does not
+ # exist and that no record type C will follow.
+ # &next_token();
+
+ # DEM spacial resolution. Usually (3,3,1) (3,6,1) or (3,9,1)
+ # depending on latitude
+ $dem_resolution = &next_token();
+
+ # one dimensional arrays
+ &next_token();
+
+ # number of profiles
+ $dem_num_profiles = &next_token();
+ $dem_num_profiles = (($dem_num_profiles - 1) / $res) + 1;
+}
+
+
+# output the scene headers
+sub output_scene_hdr {
+ my($dx, $dy, $dz);
+
+ printf("mesh %s_terrain {\n", $dem_quadrangle);
+
+ $dem_x1 =~ s/D/E/; $dem_x1 += 0.0;
+ $dem_y1 =~ s/D/E/; $dem_y1 += 0.0;
+ print " // This mesh is rooted at the following coordinates (in arc seconds)\n";
+ print " origin_lat = $dem_x1\n";
+ print " origin_lon = $dem_y1\n";
+ print "\n";
+
+ print " // Number of rows and columns (needed by the parser so it can create\n";
+ print " //the proper size structure\n";
+ print " rows = $dem_num_profiles\n";
+ print " cols = $dem_num_profiles\n"; # This isn't necessarily guaranteed
+ print "\n";
+
+ ($dx, $dy, $dz) = $dem_resolution =~
+ m/(.............)(............)(............)/;
+ $dx *= $res;
+ $dy *= $res;
+ print " // Distance between x and y data points (in arc seconds)\n";
+ print " row_step = $dx\n";
+ print " col_step = $dy\n";
+ print "\n";
+}
+
+
+# output the scene close
+sub output_scene_close {
+ print "\n";
+ print "}\n";
+}
+
+
+# read and parse DEM "B" record
+sub read_b_record {
+ my($i, $j);
+
+ # row / column id of this profile
+ $prof_row = &next_token();
+ $prof_col = &next_token();
+
+ # Number of rows (elevations) and columns in this profile;
+ $prof_num_rows = &next_token();
+ $prof_num_cols = &next_token();
+
+ $prof_num_rows = (($prof_num_rows - 1) / $res) + 1;
+ # print "profile num rows = $prof_num_rows\n";
+
+ # Ground planimetric coordinates (arc-seconds) of the first
+ # elevation in the profile
+ $prof_x1 = &next_token();
+ $prof_y1 = &next_token();
+
+ # Elevation of local datum for the profile. Always zero for
+ # 1-degree DEM, the reference is mean sea level.
+ &next_token();
+
+ # Minimum and maximum elevations for the profile.
+ &next_token();
+ &next_token();
+
+ # One (usually) dimensional array ($prof_num_rows,1) of elevations
+ $prof_data = "";
+ $i = 0;
+ while ( $i < $prof_num_rows ) {
+ $prof_data .= &next_token();
+ $prof_data .= " ";
+
+ $i++;
+
+ if ( $i < $prof_num_rows ) {
+ # not on last data point
+ # skip the tokens to get requested resolution
+ for ($j = 1; $j < $res; $j++) {
+ # print "skipping ...\n";
+ &next_token();
+ }
+ }
+ }
+ chop($prof_data);
+
+ # print "$prof_data\n\n";
+}
+
+
+# output a row of data
+sub output_row {
+ print " row = ($prof_data)\n";
+}
+
+
+# return next token from input stream
+sub next_token {
+ my($token);
+
+ # print "in next token\n";
+
+ do {
+ $token = <>; chop($token);
+ if ( eof() ) {
+ $token = "_END_OF_FILE_";
+ }
+ } while ( $token eq "" );
+
+ # print "returning $token\n";
+
+ return $token;
+}
+
+while ( ($token = &next_token()) ne "_END_OF_FILE_" ) {
+ # print "'$token'\n";
+}
+
+
+#---------------------------------------------------------------------------
+# $Log$
+# Revision 1.1 1997/05/27 21:56:02 curt
+# Initial revision (with data skipping support)
+#
projects / flightgear.git / commitdiff