Andrea Aime wrote: > Hi Frank, > this is quite interesting. Can you elaborate a bit of what "one block > scanline" means? > E.g., what is the actual tiling structure of this file? > Does presence of compression affect the ability to do the subsampling? > How about quality of the output? (e.g., is GDAL reading one pixel every N to > generate > the reduced resolution version?)
One scanline blocks can be created by using GeoTIFF creation option BLOCKYSIZE. For example gdal_translate -of GTiff -co blockysize=1 -outsize 1000 1000 test_in.TIF test_out.tif gdalinfo test_out.tif ... ... Band 1 Block=1000x1 Type=Byte, ColorInterp=Red Band 2 Block=1000x1 Type=Byte, ColorInterp=Green Band 3 Block=1000x1 Type=Byte, ColorInterp=Blue I can't tell about usability for compressed images and quality of subsampling without making some tests. I could not refresh my memory with the GIS editing software I mentioned by trying if it really is so speedy. I did find program which is one single .exe file with an amazing file size of 600 MB but it appeared to be a 16-bit Windows program and I could not run it with my current computer. I remember that we did use both tiff files and Erdas LAN format which is probably something as simple to read as BIL and tiffs with one scanline per block are. -Jukka Rahkonen- Cheers Andrea -- == Our support, Your Success! Visit http://opensdi.geo-solutions.it for more information. == Ing. Andrea Aime @geowolf Technical Lead GeoSolutions S.A.S. Via Poggio alle Viti 1187 55054 Massarosa (LU) Italy phone: +39 0584 962313 fax: +39 0584 1660272 mob: +39 339 8844549 http://www.geo-solutions.it http://twitter.com/geosolutions_it ------------------------------------------------------- _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
