Thanks for these examples. That's exactly what I need.
I'll run the same test and will compare EXR and Tiff to see if one
format is better than the other.
On 10/11/2012 06:32 AM, Larry Gritz wrote:
Even when using automip and autotile, you're going to get horrible
performance if your texture cache size is not at least big enough to
hold the image.
For JPEG images, we're just calling the underlying libjpeg, we ask for
scanlines in batches, but I can't swear to the efficiency of libjpeg,
for all I know it tries to read the whole thing at once and buffer it.
I can vouch more strongly for libtiff and OpenEXR.
For film anyway, JPEG is considered a poor texture format because it
doesn't support alpha channels, is only 8 bits, is lossy, and doesn't
have any notion of MIP-mapping. So we figured it was so ill-suited to
the task that the requirement was simply to make it work, not to make
it very efficient for huge files. For that, we turn to TIFF and
OpenEXR, which tend to satisfy the whole range of requirements of a
good texture format.
If you must use this JPEG file in its original form, assuming you have
memory to burn, I would advise using a 2 GB cache. 256 or 512 MB is
just too small, that will force it to constantly need to re-read
sections of the image.
You can convert it to a tiled format with
iconvert world.topo.bathy.200411.3x21600x21600.C1.jpg --tile 64 64
tiled.tif
Took me 48 seconds (including I/O), and the file is 415 MB (versus 43
MB for the original JPEG -- but that's because it's a lossy format)
That will get it tiled, which should make a big difference.
Additionally making into a full MIP-mapped, tiled texture, via
maketx world.topo.bathy.200411.3x21600x21600.C1.jpg -o mipped.tx
That took 3 minutes and needed several GB of RAM (it's a huge file!),
and results in a 550 MB tiled MIP-mapped TIFF file, which should be
extremely efficient to texture map.
On Oct 10, 2012, at 7:33 AM, Lerenard Michel wrote:
Hi,
Brecht: thanks for your answers, it does clear things a bit.
I've enabled automap and autotile options. It does solve the memory
issue, but i get horrible peformance instead: on small files it works
with overhead, on the huge one below it was so slow i had to stop the
rendering process.(using the default 256 cache value)
Larry: the file i use to test is a huge JPEG, =>
http://eoimages.gsfc.nasa.gov/images/imagerecords/73000/73884/world.topo.bathy.200411.3x21600x21600.C1.jpg
that can be found on this page:
http://visibleearth.nasa.gov/view.php?id=73884
After thoses tests, i think i'm going to work with temp images in
EXR, converted from formats that does not support tiles:
the cache does work correctly in this case. (i checked with a 250Mo
tiled exr file)
I have not yet tested maketx, i don't know if it's a fast process,
but it seems to be a good candidate to do the work.
--------------
Michel
[email protected] <mailto:[email protected]>
_______________________________________________
Oiio-dev mailing list
[email protected] <mailto:[email protected]>
http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
--
Larry Gritz
[email protected] <mailto:[email protected]>
_______________________________________________
Oiio-dev mailing list
[email protected]
http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
_______________________________________________
Oiio-dev mailing list
[email protected]
http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
