Hi Steve,

that was really helpful. I managed to get my map listed. However the raster 
layer did not show up :( Well I didn't really expect it. ;)

>
> I believe that the byte at 0x40 is the start block of the FAT so in
> test.img it should be 2.  Patching that byte did not make it load
> though.

Indeed, it seems to be an offset in number of 0x200 blocks. In all my example 
maps it's set to 8 and FAT starts at 0x1000. In your map it's set to 2 and FAT 
starts at 0x400. Another mystery solved.

I guess the next step is to get a rectangular extended polygon without the 
raster data to show up. The polygon type for the raster map tiles used is 
0x10613. Usually it only contains a single point as the extended data 
referencing the jpeg tile has the four boundaries coded as 32 bit integers.

My goal is to remove the extended data and to code all 4 corner coordinates. 
This should give me a matrix of all rectangles. Again this raises the question 
about the minimum effort necessary to add a single polygon. In my naive point 
of view it would be just encoding it into the extended polygon section of the 
RGN file.  Of course I tried it and it does not work. So I am missing 
something, or have a couple of more bugs in my code.

Would it be possible to code another file with a single polygon

QPolygonF(
    QPointF(11.7914,46.9628)
    QPointF(11.8021,46.9628)
    QPointF(11.8021,46.9555)
    QPointF(11.7914,46.9555)
)

coded in three map levels: 0/24bit, 1/23bit and 2/22bit. This would give me a 
nice working reference to compare.

Thanks & Cheers

Oliver




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