[Xastir] Maps

[Curt, WE7U]

On Fri, 24 Jun 2011, WE0Z wrote:

> I have not gotten experienced enough to develop my own map library so I rely 
> of the Internet download from Osmerander. While I see it downloads the tiles 
> and paints the map and I realize it takes time to download and then it caches 
> maps every time it downloads new tiles.
>
> The question I have is those tiles that have been cached where do they go as 
> I cannot seem to find them and also if they are stored on the disk why does 
> it take so long to repaint the map from the disk? Is there something I can 
> do. I am running dual-core 32-bit with 2GB RAM.

I'm usually running 4GB dual-core 64-bit systems and the drawing takes about as long as I would expect it to for raster tiles.  I run very small-memory 32-bit systems on laptops for events and am generally still pleased with the map rendering time.  Often I'm running Shapefile maps instead on those machines 'cuz I don't always have internet access during an event.

OSM tiles are saved in the "~/.xastir/OSMtiles/" directory.

I don't know if any profiling has been done since the OSM code was written.  The codebase was profiled prior to that a couple of times, first the non-map code, then each individual map type.  It's possible that another round of profiling for the OSM code would benefit us.

Anyone interesting in trying it:  There are notes near the end of the "INSTALL" file that detail how to profile the code.  The last time I profiled the map code I added a loop to the the map code so that it loaded each selected map 1000 times, then ran the profiler once per map type to determine which map code needed work.  Without that tweak it was difficult to see the map code in the profiling stats at all.

BTW:  Regarding the note in my signature below:  The WE7U-WX server is down at the moment due to a problem on the server.  I'll try to get that back up after Field Day is over.

-- 
Curt, WE7U.        http://www.eskimo.com/~archer
U.S. Weather Alerts:  Firenet.us, port 14580, filter "t/n e/WE7U-WX"