--- a/bin/ltpict.pl	Tue Apr 08 22:56:34 2014 +0100
+++ b/bin/ltpict.pl	Mon Apr 14 22:18:50 2014 +0100
@@ -47,18 +47,21 @@
     shift @ARGV;
 }
 
-if ($is_ies == 0) {
+# We need exactly one Radiance luminaires or IES file
+if (! $#ARGV == 0) {
+	die("ltpict: Need one Radiance luminaire or IES file.\n");
+} elsif ($is_ies == 0) {
 	# Input file is a Radiance luminaire
 	$lumi = $ARGV[0];
 } else {
 	# Input file is IES photometry
-	system "ies2rad -p $td -o lumi $ARGV[0]";
+	system qq[ ies2rad -p $td -o lumi "$ARGV[0]" ];
 }
 
 my $res2 = $res / 2;    # Each rendering is half the size of final composite
 
 # Scale luminaire and center at origin
-my $dimstr = `getbbox -h $lumi`;
+my $dimstr = `getbbox -h "$lumi"`;
 chomp $dimstr;
 # Values returned by getbbox are indented and delimited with multiple spaces.
 $dimstr =~ s/^\s+//;                # remove leading spaces
@@ -74,11 +77,7 @@
 my $ytrans = -1.0 * ($dims[2] + $dims[3]) / 2;
 my $ztrans = -1.0 * ($dims[4] + $dims[5]) / 2;
 my $scale = $maxsize / $size;
-
-open(FH, ">$lumi2") or
-		die("ltpict: Cannot write to temporary file $lumi");
-print FH "!xform -t $xtrans $ytrans $ztrans -s $scale $lumi";
-close FH;
+system qq[ xform -t $xtrans $ytrans $ztrans "$lumi" > $lumi2 ];
 
 
 # Material for the room
@@ -123,6 +122,7 @@
 $dimstr =~ s/^\s+//;             # remove leading spaces
 @dims = split(/\s+/, $dimstr);   # convert to array
 
+
 # Define the four views
 my $vw1 = "-vtl -vp 4.5 0 0 -vd -1 0 0 -vh 10 -vv 10";
 my $vw2 = "-vtl -vp 0 -4.5 0 -vd 0 1 0 -vh 10 -vv 10";
@@ -131,6 +131,8 @@
 my $zcent4 = $dims[5] + $tiny;
 my $vw4 = "-vta -vp 0 0 $zcent4 -vd 0 0 1 -vu 0 1 0 -vh 180 -vv 180";
 
+
+# Compile octrees
 system "oconv $mat $room1 $lumi2 > $oct1";
 system "oconv $mat $room2 $lumi2 > $oct2";
 system "oconv $mat $room3 $lumi2 > $oct3";