On Apr 5, 2010, at 12:33 PM, Matt Klaric wrote:
>
> On Mon, Apr 5, 2010 at 2:20 PM, William Kyngesburye <wokl...@kyngchaos.com>
> wrote:
> I thinking of creating a vrt for approx 19000 geotiff DEM tiles (SRTM). Any
> comments on the performance or practicality of this? Is there a difference
> in performance between Geotiff and GRASS as the tile format?
>
> Mainly it's so I can easily extract regions for projects, so it would be
> one-shot gdal_translate runs.
>
>
> I've done something similar.
>
> Check out the SourceProperties tag in http://www.gdal.org/gdal_vrttut.html.
> If you specify that for each source image, then GDAL doesn't have to open all
> 19000 images at runtime. The performance is quite good.
Looking at the vrt from the file I built with my drg images, I have this:
<SimpleSource>
<SourceFilename
relativeToVRT="1">./barrett_canyon/o39117a4.tif</SourceFilename>
<SourceBand>1</SourceBand>
<SourceProperties RasterXSize="4463" RasterYSize="5710" DataType="Byte"
BlockXSize="4463" BlockYSize="1"/>
<SrcRect xOff="0" yOff="0" xSize="4463" ySize="5710"/>
<DstRect xOff="92733" yOff="134498" xSize="4473" ySize="5723"/>
</SimpleSource>
So, presumably, gdalbuildvrt generates this for you. Is there something missing
here to achieve what you are talking about, Matt?
Thanks,
John_______________________________________________
gdal-dev mailing list
gdal-dev@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/gdal-dev
