Comments on: Bending the Earth — gdalwarp and the Blue Marble http://egb13.net/2009/04/bending-the-earth-gdalwarp-and-the-blue-marble/ Time-lapse, weather, maps, and more Thu, 15 Apr 2010 15:28:42 -0400 http://wordpress.org/?v=2.8.6 hourly 1 By: Tom MacWright http://egb13.net/2009/04/bending-the-earth-gdalwarp-and-the-blue-marble/comment-page-1/#comment-20 Tom MacWright Thu, 08 Oct 2009 11:33:42 +0000 http://egb13.net/?p=108#comment-20 One thing to note for people who are having problems with gdalwarp being fast enough, one of the problems that GDAL has a preset cache size, so it isn't using your many gigs of ram automatically. run it with gdalwarp --config GDAL_CACHEMAX 500 -wm 500 subsituting 500 for how many megs you want to give it, and, in my experience, you can get some great performance increases. One thing to note for people who are having problems with gdalwarp being fast enough, one of the problems that GDAL has a preset cache size, so it isn’t using your many gigs of ram automatically. run it with

gdalwarp –config GDAL_CACHEMAX 500 -wm 500

subsituting 500 for how many megs you want to give it, and, in my experience, you can get some great performance increases.

]]> By: Mark http://egb13.net/2009/04/bending-the-earth-gdalwarp-and-the-blue-marble/comment-page-1/#comment-15 Mark Wed, 22 Apr 2009 15:41:59 +0000 http://egb13.net/?p=108#comment-15 Yep, huge! I did finally get it to work with that plugin, just a long processing time, of course... we'll play with tiling into gdalwarp next time around. Anyway, thanks again for this post, it was an invaluable introduction to all the principles involved! Yep, huge! I did finally get it to work with that plugin, just a long processing time, of course… we’ll play with tiling into gdalwarp next time around. Anyway, thanks again for this post, it was an invaluable introduction to all the principles involved!

]]> By: egb13 http://egb13.net/2009/04/bending-the-earth-gdalwarp-and-the-blue-marble/comment-page-1/#comment-13 egb13 Tue, 21 Apr 2009 22:33:58 +0000 http://egb13.net/?p=108#comment-13 Gdalwarp can mosaic images together. An interesting experiment would be to chop the full-size image into smaller ones, still at full resolution, and warp them individually into a larger composite. BTW, my 21600x10800 image printed at 300dpi would be 6'x3' (~2m x 1m), and your 86400x43200 would come out to 24'x12' (~8m x 4m)! Gdalwarp can mosaic images together. An interesting experiment would be to chop the full-size image into smaller ones, still at full resolution, and warp them individually into a larger composite. BTW, my 21600×10800 image printed at 300dpi would be 6′x3′ (~2m x 1m), and your 86400×43200 would come out to 24′x12′ (~8m x 4m)!

]]> By: Mark http://egb13.net/2009/04/bending-the-earth-gdalwarp-and-the-blue-marble/comment-page-1/#comment-12 Mark Tue, 21 Apr 2009 22:31:25 +0000 http://egb13.net/?p=108#comment-12 @egb13, thanks for the reply. Yes, I had the same results, mine (4GB RAM) ran to just past 20% then kicked back out... What I did manage to locate is a commercial Photoshop plugin that seems robust enough to handle these quite readily... downloaded the trial, it's running a test on the 86400px image right now; we'll see how it turns out. http://www.avenza.com/products.geographicimager.html @egb13, thanks for the reply. Yes, I had the same results, mine (4GB RAM) ran to just past 20% then kicked back out…

What I did manage to locate is a commercial Photoshop plugin that seems robust enough to handle these quite readily… downloaded the trial, it’s running a test on the 86400px image right now; we’ll see how it turns out. http://www.avenza.com/products.geographicimager.html

]]> By: egb13 http://egb13.net/2009/04/bending-the-earth-gdalwarp-and-the-blue-marble/comment-page-1/#comment-11 egb13 Tue, 21 Apr 2009 21:30:52 +0000 http://egb13.net/?p=108#comment-11 @Mark; I'm don't know the limits of gdalwarp are, but I seem to have run into them. I tried to do a whole earth Albers equal area projection of the image at http://veimages.gsfc.nasa.gov/2433/land_shallow_topo_21600.tif, which is 21600x10800 pixels. Gdalwarp tried to swallow it but failed, saying, "ERROR 1: Too many points (441 out of 441) failed to transform, unable to compute output bounds.". It continued on anyway, but the output image was incomplete. The fact that it continued rather than bombing out immediately upon issuing the error makes it seem more like an internal limit than a lack of available system memory for handling such a huge image, but I don't know. I only have 1GB of RAM in the system I use for most of this stuff. Google didn't help much with this error. The energetic are invited to scan the source code to determine the source of the problem. @Mark; I’m don’t know the limits of gdalwarp are, but I seem to have run into them. I tried to do a whole earth Albers equal area projection of the image at http://veimages.gsfc.nasa.gov/2433/land_shallow_topo_21600.tif, which is 21600×10800 pixels. Gdalwarp tried to swallow it but failed, saying, “ERROR 1: Too many points (441 out of 441) failed to transform, unable to compute output bounds.”. It continued on anyway, but the output image was incomplete. The fact that it continued rather than bombing out immediately upon issuing the error makes it seem more like an internal limit than a lack of available system memory for handling such a huge image, but I don’t know. I only have 1GB of RAM in the system I use for most of this stuff.

Google didn’t help much with this error. The energetic are invited to scan the source code to determine the source of the problem.

]]> By: Mark http://egb13.net/2009/04/bending-the-earth-gdalwarp-and-the-blue-marble/comment-page-1/#comment-10 Mark Tue, 21 Apr 2009 19:35:34 +0000 http://egb13.net/?p=108#comment-10 That's wonderful, thanks for the intro. Been playing today with using gdalwarp on the full-res blue marble image (86400x43200), as remarkably I was doing for an internet search of how to do an AEA projection warp of that very image and of course came across this posting, but gdalwarp would appear to be limited to images of 17546 strips? Have you tried this technique with (much) larger images? That’s wonderful, thanks for the intro. Been playing today with using gdalwarp on the full-res blue marble image (86400×43200), as remarkably I was doing for an internet search of how to do an AEA projection warp of that very image and of course came across this posting, but gdalwarp would appear to be limited to images of 17546 strips? Have you tried this technique with (much) larger images?

]]> By: Robert Firth http://egb13.net/2009/04/bending-the-earth-gdalwarp-and-the-blue-marble/comment-page-1/#comment-7 Robert Firth Sun, 05 Apr 2009 06:13:59 +0000 http://egb13.net/?p=108#comment-7 Very good! I really appreciate the effort you put into documenting this! Very good! I really appreciate the effort you put into documenting this!

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