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

Wed Oct 11 10:51:46 BST 2023

Hi Gerd

Looking at the code, there shouldn't be any crash from mkgmap if a contour line doesn't have an
"ele" tag. I assume the Garmin device will just draw the appropriate line without a label. This
might be common where alternate contours are not given heights.

So, no; I don't think you should add any checks.

Ticker

On Wed, 2023-10-11 at 08:16 +0000, Gerd Petermann wrote:
> 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
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