No good reason. I'm more familiar with the other commands since I use them often is the main reason. A side benefit is that I can match existing tiles on other datasets and adopt existing tile names too. Now that I've read the utility pages for gdal_merge and gdal_retile I see that would be an easier method. I'll try that next time and report if I have problems. The reason I recommended it to Gilles was that the method he was trying was not going smoothly.
Thanks for contributing these utilities. Bests, Eli >>> "Christian Müller" <christian.muel...@nvoe.at> 3/23/2010 10:40 PM >>> A short question Why did you not use 1) gdal_merge 2) gdal_translate 3) gdal_retile Btw, if there is no need for reprojection, gdal_retile alone does the job. Did you have problems using these utilities ? Eli Adam writes: > Gilles, > I do a similar process (build large vrt mosaic, reproject the > mosaic vrt to another vrt, tile the reprojected mosaic vrt in new > projection to tif) although my end tiles are in tif and not compressed. > My method is the brute force way and not elegant at all. You may also > want to know that I have been advised > (http://news.gmane.org/gmane.comp.gis.gdal.devel) that this is very > inefficient and pushing the VRT format. Steps 1 and 2 are the same as > you describe. > > 1) create a single GDAL layer from all initial tiles with gdalbuildvrt > 2) reproject this virtual raster with gdalwarp (outputs a new .vrt) > 3) Tile it with gdal_translate: gdal_translate -projwin 7288440 446648 > 7306569 429923 mosaicvrtprj.vrt tile1.tif > > The brute force part is between 2 and 3. Make a vector file (shp or > PostGIS) grid of the new tiles in the desired projection. Convert the > polygon grid to points, then using SQL in a database, group by the > polygon name (which needs to be retained when converted to points) and > take the min/max of x and y. Then use SQL to concatenate gdal_translate > commands with the correct parameters. The end result is a table of > gdal_translate commands that will make the tiles. Save as text and make > needed minimal modification to fire off all those commands. Not an > elegant method at all. It could probably be done all in bash with > gdalinfo, grep, and sed, which would at least not require a database, > even if it still is a brute force method. > > I don't know if using ecw and other formats or compression options may > prevent the reading through of vrt files. My work has been simpler, > uncompressed tif from AI binary grids. You may also want to make sure > that each of your vrt files has all the proper projection and other > information from steps 1 and 2. gdalinfo ortho-dept04-2004-lam93.vrt > might help. > > > Bests, Eli > > > 2. Re: How to divide a raster layer into a set of tiles? > (Gilles Bassi?re) > 3. Re: Re: How to divide a raster layer into a set of tiles? > (Gilles Bassi?re) > 4. Re: How to divide a raster layer into a set of tiles? > (Jukka Rahkonen) > > ------------------------------ > > Message: 2 > Date: Tue, 23 Mar 2010 16:01:33 +0100 > From: Gilles Bassi?re <gbassi...@gmail.com> > Subject: [gdal-dev] Re: How to divide a raster layer into a set of > tiles? > To: Christian M?ller <christian.muel...@nvoe.at> > Cc: gdal-dev@lists.osgeo.org > Message-ID: <4ba8d7cd.1050...@gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Christian Müller wrote: >> That is a surprise. >> In all my tests I had no memory problems with gdal_retile. Sometimes > I >> had some memory problems with gdal_merge. The biggest input file for >> gdal_retile was a 80 GB Erdas image (not compressed) and it works > fine. >> I have never testet with an ECW File and my tests run on a Linux Box > or >> AIX Box. >> Perhaps the problem is in the ECW gdal driver. You can try to > transform >> your ecw file in another format using gdal_transform. >> > > That's may be caused by something wrong with the ECW driver indeed. I > will test gdal_retile again once I have a clean GDAL+ECW install. > > Regards > Gilles > >> >> >> Gilles Bassière writes: >>> Christian Müller wrote: >>>> gdal_retile.py definitely creates georeferenced tiles, I developed > this >>>> utility. >>>> I did some experiments reprojecting the single tiles while > retiling, but >>>> it simply does not work. As a consequence I canceled the > reprojecting >>>> support. >>>> The solution for your problem is: >>>> 1) Use gdal_merge to create the big image >>>> 2) reproject with gdal_warp >>>> 3) use gdal_retile to create your new tiles >>>> I did a lot of experiments to avoid creating the big picture > without >>>> success. >>> >>> I understand. In my case, gdal_retile.py eventually crashed with a >>> Python MemoryError. I assume it is unsurprising with a 7.5GB input > for a >>> single Python process. >>>> >>>> Even Rouault writes: >>>>> Le Monday 22 March 2010 19:35:47 Gilles Bassière, vous avez écrit > : >>>>>> Hi, >>>>>> The problem with this workflow is that it creates > non-georeferenced >>>>>> tiles (I don't know if this is the intended behaviour of this >>>>>> command). >>>>> >>>>> gdal_retile.py *does* create georeferenced tiles. I've just > verified >>>>> it. What make you think the contrary ? >>>>> _______________________________________________ >>>>> gdal-dev mailing list >>>>> gdal-dev@lists.osgeo.org >>>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev >>>> >>>> >>>> _______________________________________________ >>>> gdal-dev mailing list >>>> gdal-dev@lists.osgeo.org >>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev >>> >>> >>> -- >>> Gilles Bassière - Web/GIS software engineer >>> http://gbassiere.free.fr/ >> >> > > > -- > Gilles Bassière - Web/GIS software engineer > http://gbassiere.free.fr/ > > > ------------------------------ > > Message: 3 > Date: Tue, 23 Mar 2010 16:08:58 +0100 > From: Gilles Bassi?re <gbassi...@gmail.com> > Subject: Re: [gdal-dev] Re: How to divide a raster layer into a set of > tiles? > To: Jukka Rahkonen <jukka.rahko...@mmmtike.fi> > Cc: gdal-dev@lists.osgeo.org > Message-ID: <4ba8d98a.2020...@gmail.com> > Content-Type: text/plain; charset=UTF-8 > > Jukka Rahkonen wrote: >> Gilles BassiÃ.re <gbassiere <at> gmail.com> writes: >> >>> Hi, >>> >>> I'm trying to reproject an aerial imagery dataset with GDAL. >>> >>> The initial dataset is composed of ECW tiles in EPSG:27572 and my > goal >>> is to compute a new set set of ECW tiles projected in EPSG:2154. >> ... >> >>> My current workflow consists in the following steps: >>> 1) create a single GDAL layer from all initial tiles with > gdalbuildvrt >>> 2) reproject this virtual raster with gdalwarp (outputs a new .vrt) >> >> I would perhaps calculate the extents I want the output tiles to have > and run >> gdalwarp for each tile with -te option. >> >> -Jukka Rahkonen- >> > > Hi Jukka, > > Thanks for your suggestion. I've been able to get the extent > automatically computed by a little Bash scripting: > > for x in `seq -w 895 5 1020`; do > for y in `seq -w 6290 5 6410`; do > e="$((10#${x}*1000)) $((10#${y}*1000)) $(((10#${x}+5)*1000)) > $(((10#${y}+5)*1000))" > echo "=== Processing tile $x-$y ===" > gdalwarp -s_srs "+init=epsg:27572" -t_srs "+init=epsg:2154" > -te > $e -ts 10000 10000 ortho-dept04-2004-la2e.vrt > ortho-dept04-2004-lam93-tif/04-2004-$x-$y-lam93.tif > done > done > > Regards > > -- > Gilles BassiÃ.re - Web/GIS software engineer > http://gbassiere.free.fr/ > > > ------------------------------ > > Message: 4 > Date: Tue, 23 Mar 2010 11:54:50 +0000 (UTC) > From: Jukka Rahkonen <jukka.rahko...@mmmtike.fi> > Subject: [gdal-dev] Re: How to divide a raster layer into a set of > tiles? > To: gdal-dev@lists.osgeo.org > Message-ID: <loom.20100323t125053-...@post.gmane.org> > Content-Type: text/plain; charset=utf-8 > > Gilles BassiÃ.re <gbassiere <at> gmail.com> writes: > >> >> Hi, >> >> I'm trying to reproject an aerial imagery dataset with GDAL. >> >> The initial dataset is composed of ECW tiles in EPSG:27572 and my > goal >> is to compute a new set set of ECW tiles projected in EPSG:2154. > > Hi, > > May I ask if you are ready with your new tiles? The task is for sure > doable with > a few alternative ways. It would be nice to know which route you > decided to > follow, perhaps with some examples of the commands you have used. > > -Jukka Rahkonen- > > > > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev