[mkgmap-dev] question regarding MapRoad

Sun Mar 23 13:27:03 GMT 2014

Hi,

 > It would probably be better to create a grid of subdivisions and cut
 > the roads at nodes near the boundary so that there is a lot less
 > overlapping.  I've no idea how much, if any, difference it would make
 > though, and it would entail a fairly substantial re-write.

Do you still consider this idea?

Cgpsmapper supports parameter "TRESIZE". I assume that this parameter 
define size of subdivision in TRE. It could be equivalent to definition 
in file MapSplitter.java:
public static final int MAX_DIVISION_SIZE = 0x7fff;

Using "TRESIZE" in cgpsmapper directly influence 2 feature of resulting 
img: file size and processing speed in device. And there are real gains 
in map redraw speed when using small values for TRESIZE. I usually set 
it for 511.

I have experimenting a bit with MAX_DIVISION_SIZE in mkgmap. I have 
observed increase in file size, when using small value, but no increase 
in processing speed. I think this discussion gives some explanations. As 
I understand, mkgmap doesn't split map objects to fit subdivisions. So 
there is no gain from using smaller subdivisions, because there is no 
reduction in processed objects size.

I would expect that proper truncating objects to subdivisions could be 
another big improvement for mkgmap. Please, don't abandon this idea.

-- 
Best regards,
Andrzej