Derek, Switching to less detailed versions is not as fast as an interactive application would like, especially if you need a good downsampling algorithm. So, adding overviews is more important than creating tiles. Creating tiles is more applicable for web applications where less disk seeking is preferable.
The gdaladdo utility [1] creates and stores the overviews on the disk. [1]: http://www.gdal.org/gdaladdo.html On Sat, Jun 11, 2011 at 9:00 AM, Cole, Derek <dc...@integrity-apps.com>wrote: > Hello again, > > I am reading over some of the documentation and information I can find on > GDAL. > > I have some pretty large NITF images that I want to break up for purposes > of displaying in a viewer I am developing. My current plan is to tile the > images into 1024x1024 blocks. The full images are 32768x32768 pixels > > I was hoping that as part of my tiling, I would read in the image blocks > and display them as they are on disk, and as a user zoomed out, switch to > "Less detailed" versions the further out they go. > > I was looking at the gdaladdo sample program. Is this what I want to be > looking at to try to replicate this functionality *in memory* for my viewer? > Ideally all of the tiles would know what level of zoom they were at, and > switch to the appropriate level of detail accordingly. > > Does it sound feasible to have my code constantly switching each tile > between an overview that is generated on the fly like that, or do people > typically write out the lower res imagesonce to file , and re-read that new > files? > > Thanks for answering! > > Derek > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev > -- Best regards, Chaitanya kumar CH. /tʃaɪθənjə/ /kʊmɑr/ +91-9494447584 17.2416N 80.1426E
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