cgpsmapper and tile size?

[Dana]

I'm trying to understand tiling and cgpsmapper.

I've got my raster conversion program (similar in principle to MOAGU in that each pixel on the input map is converted to a custom point, but optimized for larger areas, with some other differences) working pretty well now. and I'm trying to optimize the map performance on the GPS.

Working with a smaller test area, 1° X 1° and roughly 200,000 points, I found that performance improved significantly by lowering the TreSize down to 50 (below 100 generates a warning; below 50 and the map doesn't display on the GPS at all).  However, it's not clear exactly what it refers to, "maximum allowed region size".  I'm not clear what a "region" is as cgpsmapper defines it.

Moving on to the actual size images I intend to use (2400X2400, from which I'm extracting an area 4° X 4°), I find that cgpsmapper will process an area of up to about 2° square before choking, so I'm creating four .mp files of 2° square each.  However, the performance on the GPS drops dramatically.  My fast coputer at work is processing the four 2° tiles overnight right now [I hope!].

If I break it up into more smaller ,mp (e.g. sixteen 1°sq tiles instead of four 2° square tiles), will that improve the performance on the GPS?  Or is there a way to use one large .mp file and cause cgpsmapper to break it up?  It seems that I'm waiting for the GPS to display points that even aren't on the screen if I'm zoomed in closer than the entire area.

-Dana

[Dana]

Is there a limit, or a point of diminishing returns, though?

Any insight on the TreSize?

-Dana

[Dana]

Well, the four 2° tiles are unacceptably slow on the GPS, so I moved on to sixteen 1° tiles.  At about a half hour per tile for cgpsmapper to process (not counting the time to create the mp files from the raster image), I finished half of them and dumped them into the GPS.  Much better, but still not ideal.  Tomorrow I guess I'll try 64 1/2° tiles (times a half dozen or so raster images covering 4°).

-Dana

[-Oz-]

Tre size, as it decreases it can add more detail (i think).  Whenever I get memory errors I low tre to 800, then 400, then 250; but never below 250 (according to stan).  I'd try lowering to 400 and see if it changes anything.

[Dana]

I'm already using TreSize=50 (yes 50) as it makes a dramatic improvement in the map draw speed.  I just ignore the warning about it being below 100.  If I set it to less than 50 the map doesn't display at all on the GPS (just shows "no map").

TreSize seems to be related to the size of the patches that show up as the map is drawn on the GPS.

-Dana