[gdal-dev] Building Overviews for Tiles of Large images

[Chaitanya kumar CH]

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 <dcole at 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
>
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-- 
Best regards,
Chaitanya kumar CH.
/tʃaɪθənjə/ /kʊmɑr/
+91-9494447584
17.2416N 80.1426E
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