Map: Height Maps

[DRG]

A problem has developed. I tried to generate a map this morning and got an error message. I thought perhaps it was because I was using my original link but I just tried the one you provided in post 131 and the same message appears

Something went wrong, return value 2. Process returned:
Can't locate JSON.pm in @INC (you may need to install the JSON module) (@INC contains: /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.22.1 /usr/local/share/perl/5.22.1 /usr/lib/x86_64-linux-gnu/perl5/5.22 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl/5.22 /usr/share/perl/5.22 /usr/local/lib/site_perl /usr/lib/x86_64-linux-gnu/perl-base .) at contour.pl line 9.
BEGIN failed--compilation aborted at contour.pl line 9.

What is ........" the JSON module " ?