[mkgmap-dev] Embedding raster maps

Tue Jan 25 11:23:46 GMT 2022

Hi developers,

yes, RGN5 contains one or more Huffman decoding sections.
For the Ile of man map there is only one table with symbol width 32,
in a CN Europe NTU tile I find 5 different tables, two with symbol width 8 and three with 32.

A lot more to learn here..

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <gpetermann_muenchen at hotmail.com>
Gesendet: Dienstag, 25. Januar 2022 09:53
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] Embedding raster maps

Hi Ticker,

yes, that's right. I am working on an implementation, but it will take a while ...
The Huffman table in the Ile of man map is probably used to decode the raster image. I has a symbol width of 32.
Just starting to learn how it works, GPXSee is a great help but the code is hard to read.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
Gesendet: Dienstag, 25. Januar 2022 09:45
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] Embedding raster maps

Hi Gerd

When I looked at this (not very closely) a couple of weeks ago, it
seemed as if LBL could be huffman encoded, with ENCODING_FORMAT set to
11, and the decoding table somewhere in RGN

Ticker

On Tue, 2022-01-25 at 08:10 +0000, Gerd Petermann wrote:
> Hi Steve,
>
> if I got that right data in RGN5 is like MDR16, means, it contains
> Huffman decoding data. At least a lot of bytes look similar
> and GPXSee also gets the decoding data from it.
>
> Most of the code that displays MDR16 can be used to read RGN5, too.
>
> Gerd

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