Author Topic: File size for offline raster maps  (Read 1732 times)

Offline skids

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File size for offline raster maps
« on: May 28, 2012, 13:03:39 »
Hi there
I've recently been updating some of my offline maps, which are the UK Ordnance survey.  The reason for this is because I wasn't happy with which zoom level my old maps switched from the 1:50,000 style to 1:25:000 style.  I want zoom levels 12&13 for the whole UK, and 14&15 for certain areas.

I'm using Mobile Atlas Creator 1.8 (an old version which still has Ordnance Survey in its list of map sources).  However - I've noticed that my new maps files are a lot larger (more than double) than my old maps, even though they are roughly the same area and same number of zoom levels.  Does anyone have any ideas why this may be?  I thought maybe the resolution/file size of the tiles from this map source has changed since I last downloaded maps.  I don't know the url of this map source because I don't know where to find this for MOBAC 1.8.  Unfortunately I cleared the cache of tiles in MOBAC (which were proabably of the old smaller file size) - otherwise I suspect my maps would have come out just the same as before.  The file size I'm getting now is comparable to the size I get using locus to download.

Also, is there any way of compressing the size of these map files?  Does anyone know of a utility which will take all the individual tiles in the map and compress them to smaller size jpeg, for example.  I'm after something nice and easy for a non-programmer to use!
« Last Edit: January 01, 1970, 01:00:00 by Guest »

Offline brotbuexe

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Re: File size for offline raster maps
« Reply #1 on: May 28, 2012, 23:10:05 »
You should be able to recompress the tiles in mobac while creating the atlas. its in the left side. if the mapsource use png files you can try creating jpeg (you can define the compressionlevel) instead of png. It gets applied only to the created atlases, the tilecache in mobac is still the untouched sourcefiles, so you can try different settings.
« Last Edit: January 01, 1970, 01:00:00 by Guest »