 | | | Camera projections & elliptical filtering | Camera projections & elliptical filtering 2004-03-09 - By Bernard Lebel
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Ok I'll give more details because I did my little investigation, and there
are things that I didn't know at that moment.
The way we have been working so far is that the texture artists do some
prelighting on the textures by baking shadows on the textures, using
rendermaps. I thought they were using camera projections throughout the
whole process but they are not, they unwrap the UVs standard style. They
rendermap using the original projection, then reapply the rendermapped
textures using the same projection again. So now I'm pretty sure our
problems are not related to the projections.
Our problem is this: We are trying to use .map files with pyramidal
filtering but it doesn't seem to be working as it should.
The way the texture folks are creating the .map files is that they create 12
versions of the same textures at different resolutions, and combine them
into a single .map fil using "imf_copy -p -c" options. Could the -c option
be broken?
Now, the only way we can get the different resolution textures of the .map
files is by using elliptical filtering. Otherwise, it seems we are stuck
with the maximum resolution image. But when we activate elliptical
filtering, we get terrible artefacts. The "layers" do not blend properly, we
get blockiness. Therefore, we can't take advantage of the technique at all,
the entire image is loaded in memory at render time. Since we work at film
res........... Batchserve barfs crashes and errors.
I thought it had to do with camera projections because elliptical filtering
is very sensitive to the projection you're using. But I found that camera
projections were not used 99% of the time. So I discard this cause. Planar
and cylindrical projections are used most of the time.
So to summarize....
- Could the -c option be broken? It doesn't seem so, as it combines properly
the input textures.
- But then would it better to use one input file with only the -p option?
- Are there known problem with elliptical filtering and pyramidal map files?
The mr docs says they have to be used in conjonction to get smooth results,
but we don't get smooth results at all (though this area is still under
investigation).
Any other suggestion?
Thanks a lot
Bernard
http://www.bernardlebel.com
http://www.xsimontreal.com
http://www.xsibase.com
>From: A_K <xsi@(protected)>
>Reply-To: XSI@(protected)
>To: Bernard Lebel <XSI@(protected)>
>Subject: Re: Camera projections & elliptical filtering
>Date: Tue, 9 Mar 2004 02:16:51 +0200
>
>Hello Bernard,
>
>did you try changing from explicit to implicit in the
>projection menu?
>
>BL> Hello,
>
>BL> Has anyone had any problem with camera projections and elliptical
>filtering?
>
>BL> The texture folks here use camera projections most of the time, and
>thye
>BL> convert to pyramidal filtered .map files.
>BL> Now, since we have to use elliptical filtering to get good results with
>BL> pyramidal files, we get prettyweird artefacts. I mean serious stuff,
>the
>BL> kind that is not usable (the various resolution textures blend awefully
>BL> together).
>BL> Now after a reading of the mr docs, I begin to suspect that it is
>related to
>BL> camera projections, even though they are generally frozen before
>rendering.
>
>BL> Any help or pointer in the right direction would be quite wlecome.
>
>
>BL> Thanks
>BL> Bernard
>
>
>
>BL> http://www.bernardlebel.com
>BL> http://www.xsimontreal.com
>BL> http://www.xsibase.com
>
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>Best regards,
> A_K mailto:xsi@(protected)
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