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Re: [udig-devel] Large GeoTiff not rendering at high zoom
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Dear Ned,
can you paste a gdalinfo for this tiff here?
Anyway, I would suggest you first rewrite your image as a tiled tiff
using gdal_translate and the BLOCKXSIZE/BLOCKYSIZE creation options
from geotiff (this will solve the issue at high resolution).
Then you proceed with overview as indicated.
Regards,
Simone.
-------------------------------------------------------
Ing. Simone Giannecchini
GeoSolutions S.A.S.
Founder
Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy
phone: +39 0584962313
fax: +39 0584962313
mob: +39 333 8128928
http://www.geo-solutions.it
http://geo-solutions.blogspot.com/
http://www.linkedin.com/in/simonegiannecchini
http://twitter.com/simogeo
-------------------------------------------------------
On Wed, Jan 19, 2011 at 9:02 PM, Ned Haubein <bluehen597@xxxxxxxxx> wrote:
> Hi,
>
> After working for a while to get a large GeoTiff file (2.7GB, 51511x67140 pixels) into uDig 1.2, I thought I'd share my approach for new users and ask a question of the more experienced.
>
> Just dragging that large of a file into uDig didn't work - the layer would show up in the layers list and an entry in the Catalog, but nothing rendered. It would show progress for a while and then silently stop. The only error I saw was when entering the layer properties. The histogram building failed due to width*height>Integer.MAX.
>
> After some searching, I was successful in using GDAL to add overviews to the tiff file:
>
> gdaladdo -r average filename.tif 2 4 8 16
>
> I got a few warnings about "computing overviews on raster palette index", but the output images seemed to look ok for the most part.
>
> When dragging the new tiff into uDig it renders fine and is actually pretty snappy in its rendering.
>
> Now to my question: When I zoom in too far (past 1:2921 scale), the raster layer just disappears. Other layers are drawn fine, and if I zoom out the raster from the geotiff renders ok again. There are no log or console errors. Any ideas what is going on? Am I basically just seeing the same initial problem of not being able to render the base level of the image b/c I have zoomed in past the "overview 2" level? Has anyone seen this? Are there workarounds?
>
> I did build a pyramid using gdal_retile. I could import a mosaic directory into udig for the lower resolution levels, but only the level imported was visible - no transitions up and down the pyramid when zooming, so I think gdaladdo was the right choice.
>
> Any thoughts or suggestions welcome.
>
> Thanks to the developers,
>
> - Ned
>
>
>
> _______________________________________________
> User-friendly Desktop Internet GIS (uDig)
> http://udig.refractions.net
> http://lists.refractions.net/mailman/listinfo/udig-devel
>
