height

#!/usr/bin/env perl

use Data::Dumper;
use FindBin;
use lib "$FindBin::Bin/lib";
use Geo::Coordinates::OSGB qw(ll_to_grid grid_to_ll);
use Geo::Coordinates::OSTN02;
use Elevation;
use Getopt::Long;
use Carp;
$SIG{__DIE__} = sub { Carp::confess @_ };

my $help;
my $elevation_plugin;

BEGIN { 
	sub load_config
	{
		my( $file ) = @_;
		my $return;
		unless ($return = do $file) {
			warn "couldn't parse $file: $@" if $@;
			warn "couldn't do $file: $!"    unless defined $return;
			warn "couldn't run $file"       unless $return;
			exit 1;
		}
	}

	sub help 
	{
		print "$0 <lat>,<long>\n";
		print "Additional options: \n";
		print "  --elevation <plugin>\n";
	}

	if( !GetOptions (
		"elevation=s" => \$elevation_plugin,
	)) {
		print STDERR ("Error in command line arguments\n");
		help();
		exit( 1 );
	}


}

use strict;
use warnings;

if( $help )
{
	help();
	exit( 0 );
}


my $centre = $ARGV[0];

############################### ###############################

if( !-d "$FindBin::Bin/var" ) { mkdir( "$FindBin::Bin/var" ); }
if( !-d "$FindBin::Bin/var/tiles" ) { mkdir( "$FindBin::Bin/var/tiles" ); }
if( !-d "$FindBin::Bin/var/tmp" ) { mkdir( "$FindBin::Bin/var/tmp" ); }
if( !-d "$FindBin::Bin/var/lidar" ) { mkdir( "$FindBin::Bin/var/lidar" ); }
if( !-d "$FindBin::Bin/var/lidar/DSM" ) { mkdir( "$FindBin::Bin/var/lidar/DSM" ); }
if( !-d "$FindBin::Bin/var/lidar/DTM" ) { mkdir( "$FindBin::Bin/var/lidar/DTM" ); }

$elevation_plugin = "UKDEFRA" if( !defined $elevation_plugin );
my $rc = eval "use Elevation::$elevation_plugin; 1;";
if( !$rc ) {
	die "Error in loading elevation; $@";
}
my $elevation = "Elevation::$elevation_plugin"->new( 
	"$FindBin::Bin/var/lidar", 
	"$FindBin::Bin/var/tmp", 
);

my( $lat, $long ) = split( /,/,$centre);

no strict 'refs';
my $ll_to_en = "Elevation::".$elevation_plugin."::ll_to_en";
my( $e,$n ) = &$ll_to_en( $lat,$long );
use strict 'refs';

my $data = {};
my $SPREAD=2;
for( my $xo=-$SPREAD; $xo<=$SPREAD; ++$xo ) 
{
	for( my $yo=-$SPREAD; $yo<=$SPREAD; ++$yo ) 
	{
		my $dsm = $elevation->en( "DSM", $e+$xo, $n+$yo );
		my $dtm = $elevation->en( "DTM", $e+$xo, $n+$yo );
		push @{$data->{DSM}}, $dsm;
		push @{$data->{DTM}}, $dtm;
		push @{$data->{DIFF}}, $dsm-$dtm;
	}
}
print sprintf( 
	"DSM: % 3.2fm\nDTM: % 3.2fm\nHEIGHT: % 3.2fm\n", 
	median( $data->{DSM} ),
	median( $data->{DTM} ),
	median( $data->{DIFF} ) );
exit;

sub median 
{
	my( $list ) = @_;

	my $i = int( ( scalar @$list ) / 2 );

	return $list->[$i];
}