[gdal-dev] vrt performance with 1000's of tiles?
schut at sarvision.nl
Tue Apr 6 03:36:14 EDT 2010
FWIW, I've done something similar (worldwide vrt of all cgiar srtm4
tiles), which is working flawlessly and performance is good. However, I
am not using it for direct viewing, just to be able to extract arbitrary
subsets of specific regions with gdalwarp.
If I would think of viewing the entire dataset, I think I'd rather setup
a local wms for that with tiled geotiffs with overviews (pyramids) as
input, to prevent the need to read and resample all data when a view of
the entire world is requested. For viewing, you could try to generate
some external overviews on the vrt file, maybe that solves the problem?
On 04/05/2010 09:48 PM, John C. Tull wrote:
> I would be interested in your success or failure. I have a directory of 500 usgs drg map images, and I cannot get them to tile successfully with gdalbuildvrt. I end up with a black image when I load it in visualization software. I tried to find a discussion I had on the gdal irc channel some time ago about this issue in an attempt to troubleshoot and resolve it, but it appears to not have been logged. In short, I was unable to track it to a specific cause nor find a solution. All files are the same projection, bands, etc. The directory of images occupies about 2.5 GB of disk space. There are also gaps in the region being covered, but none of this seems like it should lead to a failure.
> On Apr 5, 2010, at 12:20 PM, William Kyngesburye 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.
>> William Kyngesburye<kyngchaos*at*kyngchaos*dot*com>
>> "The beast is actively interested only in now, and, as it is always now and always shall be, there is an eternity of time for the accomplishment of objects."
>> - the wisdom of Tarzan
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