-#!/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_lon = $dem_x1\n";
- print " origin_lat = $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 1.2 1997/05/30 19:30:16 curt
-# The LaRCsim flight model is starting to look like it is working.
-#
-# Revision 1.1 1997/05/27 21:56:02 curt
-# Initial revision (with data skipping support)
-#