[mkgmap-dev] Configuration for overview map

Thu Apr 4 08:18:33 BST 2013

Hi all,

Yesterday I've committed r2546 in the overview2 branch.
In addition to the functionality implemented in overview_v3.patch this
implements 
also the support of data with extended types. Please try it with the known
options: 
--x-overview-add-polygons 
--x-overview-add-lines 
--x-overview-add-points

Now I wonder what kind of further configuration we could need.

The following points were discussed:
1) Allow to read data from other levels, not only the one with the lowest
resolution.
I tried it and I don't think this will increase quality, but it increases
run time quite heavily.

2) Allow to apply filters, so that fewer objects are placed in the overview
map.
I think this could be implemented with a simple list like this:

# filter for overview map
point:type_1 
point:type_2
...
point:type_n
line:*
polygon:

This would add points with the type type_1 to type_n, all lines and no
polygons.
The file woud replace the --x-overview-add-xxx options.
I will try to implement it in this way, please suggest changes if something
else is needed.

3) Style files for the overview map
I don't see how this could be used when the data is read from *.img files.

4) Read data from other sources, e.g. precompiled sea/land polygons.
I don't plan to code that but I think this remains a possible option to
increase quality.

Open questions:
1) The current implementation adds a background polygon with type 0x4a even
if
option --transparent is used. I assume this is correct?
2) The background is now added as a rectangle. This could be changed so that
it 
covers only the areas covered by the *.img files. Is this needed?

Ciao,
Gerd

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