[Xastir] painfully slow raster map performance

[Kevin Ratcliff]

On Fri, Mar 11, 2011 at 12:25 PM, Curt, WE7U <curt.we7u at gmail.com> wrote:
> Which raster maps?  USGS DRG's perhaps?

Yes, USGS DRG topos, and color aerial photos in Geotiff format.

> What you can do:  Set the zoom levels so that the 7.5' maps are loaded only
> at the levels where you need that detail.  Switch to the 1:100k maps above
> that, and the 1:250k maps above that.  With that scheme you can zoom in/out
> much more quickly 'cuz you've got fewer maps being loaded when you're zoomed
> out.

I only need the 1:24k maps. When I zoom out I just use some shapefiles
so I can keep oriented to where I am on the map, but primary use is
tracking ground SAR crews, so I need the detail when zoomed in.

> Another option:  Process the DRG maps into one contiguous map using GRASS or
> some other good GIS program, then break it up into smaller tiles in
> "unprojected" projection.  Create .geo files for each one and let Xastir
> have at that.  Xastir will treat it as any other raster in that case and
> tile them all together as you need, but it won't have to do all the math on
> it to get it into the right projection then.

Good idea, thanks! I'll get with a local GIS guy and try that and
report back if there's a noticeable improvement.

Kevin
KB9MQU