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[mkgmap-dev] Shifted map when supplying poly bbox to splitter

From Gerd Petermann gpetermann_muenchen at hotmail.com on Thu Dec 13 16:16:14 GMT 2018

Hi Joris,

splitter rounds the values to multiples of Garmin units. The corresponding messages in the log:
Map is being split for resolution 13:
 - area boundaries are aligned to 0x800 map units (0.0439453125 degrees)
 - areas are multiples of 0x800 map units wide and high
Processing \osm\63240001.osm.pbf
Bounding box 13.491210937 52.294921875 13.798828125 52.690429687000005
Fill-densities-map pass took 1110 ms
Exact map coverage read from input file(s) is (52.294921875,13.4912109375) to (52.6904296875,13.798828125)
Rounded map coverage is (52.294921875,13.4912109375) to (52.6904296875,13.798828125)


Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Joris Bo <jorisbo at hotmail.com>
Gesendet: Donnerstag, 13. Dezember 2018 17:12
An: Development list for mkgmap
Betreff: [mkgmap-dev] Shifted map when supplying poly bbox to splitter


When using a poly file with a bbox for splitter on ‘small areas’ the resulting map is shifted / not complete.
I assume it uses some rounding algoritm to redefine the coordinates specified.
Could somebody explain me how to predict this behaviour.
When starting from a center point : how many degrees  should it minimum be extended to left, right, up and down ?
Or maybe I do something wrong with the poly file.

Kind regards

Here is an example where I specified a small bbox around a city centre.
After supplying this to splitter in this case it only returns approximately the left/down quarter and the centre point is not included
[cid:image001.jpg at 01D49307.0FB4AC60]
Supplied poly to splitter

Splitter areas.polys result file

JBM - Temp
   5.01   52.02
   5.01   52.09
   5.11   52.09
   5.11   52.02
   5.01   52.02 (tested both with and without this line)

  5.010002  52.020006
  5.010002  52.090001
  5.109994  52.090001
  5.109994  52.020006
  5.010002  52.020006

[cid:image002.jpg at 01D49307.0FB4AC60]

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