[mkgmap-dev] Map display squeezed horizontally

Thu Apr 18 07:33:30 BST 2013

Hello Michael,

the algorithms used in mkgmap could explain some shifting of elements, but I have no idea how a squeeze could
happen.
The img format requires mkgmap to distribute data to different so called sub divisions, the positions of elements are
saved relative to these sub divisions. The more details your map contains, the more sub divs are created. So that would explain 
small changes when a style adds more details.
The sub divisions may overlap, and I assume that rounding errors can cause that you see two objects
that are saved in different sub divs with a different distance.
I don't know if this can explain what you see?

Gerd

> Date: Thu, 18 Apr 2013 01:49:22 +0200
> From: mipri at gmx.net
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: [mkgmap-dev] Map display squeezed horizontally
> 
> 
> Hello,
> 
> while examining the wrong labels in Mapsource I found another strange 
> problem with my map. Compared with other maps, my own map seems to be 
> squeezed horizontally. I made a screenshot to illustrate this, please 
> see http://www.mipri.de/dl/maps.png
> 
> I've mounted two screenshots side by side. Both are made from exactly 
> the same Mapsource window, I just switched the map. The left is my own 
> map, the right a map created without own style and TYP file.
> 
> While the height is absolutely identical in both maps, my own map is 
> squeezed horizontally, showing areas that are not visible in the map on 
> the righthand side, for example the parking below the Min Map.
> 
> The scale in the lower right corner is identical in both maps, and not 
> squeezed like the map.
> 
> I've also tried other maps, they all look like the map at the right. So 
> it's definitely my own map which is displayed wrong.
> 
> 
> My map was built as follows:
> 
> - Created contour data with srtm2osm, renumbered ways and nodes so that 
> their IDs do not collide with "real" OSM IDs, converted to PBF
> 
> - Downloaded OSM data for Germany from Geofabric in PBF format
> 
> - Merged both using the latest stable osmosis
> 
> - Splitted the resulting PBF
> 
> - Created the map with the latest mkgmap
> 
> 
> Does anybody have an idea how this deformation could have been caused?
> 
> 
> Thank you for your answers,
> 
> Michael
> 
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