[mkgmap-dev] Contour lines without elevation. What shoul mkgmap do?

Wed Oct 11 09:16:28 BST 2023

Hi all,

in a private mail I was informed that mkgmap crashes when polish input contains no label for types which are considered as contour line data like this
[POLYLINE]
Type=0x20
Data0=(51.5300781,-0.0988259), (51.5305501,-0.0989852), (51.5311576,-0.0992174)
[END]

The same data was handled without problem before r4907. 
As a quick hack I've added a null check to restore the old behaviour, but I wonder if it would be better to stop with an error message
or maybe ignore contour line data when no elevation is given in the label?

I guess the same problem can happen with OSM data when a style uses the line types  0x20 .. 0x25 .
Should I add checks to warn when these line types are used without a proper label that can be elevation data? 

Gerd