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[mkgmap-dev] problems at map intersections?

From Steve Ratcliffe steve at parabola.me.uk on Sat Jul 18 13:09:31 BST 2009


I've run your example and looked at the bounding boxes of everything
important that I know about.

First the actual bounds as given in the input files.
All the bounds below I believe should be exactly equal to this.
Also the first number on the first line should be the same as the
third number on the second line bottom of 63240010 matches the
top of 63240008 (only the last four digits of the map number shown below).
0010: 52.4267578125,3.2958984375 53.6572265625,5.625
0008: 52.119140625,3.2958984375 52.4267578125,4.9658203125

Inside the overview map there are definition areas that should cover the
individual maps.
0010: 52.470703,3.339844 53.701172,5.668945
0008: 52.163086,3.339844 52.470703,5.009766
So top matches bottom, but not the same as the bounds.
This could explain mapsource, but as it is not used
on the device can't explain the problem in the GPS.

In the Tdb file we have:
0010: 52.426758,3.295898 53.657227,5.625000
0008: 52.119141,3.295898 52.426758,4.965820
So top matches bottom, and matches bounds. All good.

In the actual map the bounds are recorded in the TRE section in
this case I found:
TRE 0010: 52.4268,3.2959 53.6572,5.6250
TRE 0008: 52.1191,3.2959 52.4268,4.9658
So top matches bottom and matches bounds within the resolution
that is printed.

Inside the map there are also background polygons
of type map coverage 0x4b.
0010: 52.426758,4.751587 52.734375,5.042725
0008: 52.119141,4.757080 52.426758,4.965820
Again these look correct.

If I look at the actual location where roads etc get chopped it
is correct at 52.426758 on both maps.

So the conclusion is that the definition areas in the overview map
are wrong.  This would explain problems in mapsource, but not on the

I'll next look at what is wrong, but this email is long enough already 
and it will give a chance for people to check to see if I've missed 


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