 | | | Camera projections & elliptical filtering | Camera projections & elliptical filtering 2004-03-09 - By Bernard Lebel
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Yes indeed, I found that the texture peeps are simply decreasing the
resolution and saving them into separate files. From now on we'll not use
the -c option.
However, I spent the whole day working on that problem and I found some good
and bad things.
- The -c option actually works fine.
- Also does the pyramidal .map file.
- More importantly, the reason why we have ugly transitions between the
various resolution textures of the map file is because of the elliptical
filtering's Disc Radius parameter. The only way to create good transitions
is to crank up this parameter to an unbelievable value like 100. It's not
perfect, but at least you have a smoother transition.
- The problem now is that because of such high value, rendering time
considerably increases. For instance, with very simple things it increased
for at least 10 or 20 times.
- Since such a dramatic increase of time is not affordable, we will probably
throw away the pyramidal filtering thing and simply use .map files with no
pyramidal filtering. I will investigate scripted alternatives to have lower
resolution versions of the textures and other methods for improving
performance.
Thanks for the help, suggestions are still welcome though :-)
Harry if you need info about the -c thing drop me a mail.
Bernard
http://www.bernardlebel.com
http://www.xsimontreal.com
http://www.xsibase.com
>From: "Dave Lajoie" <davelaj@(protected)>
>Reply-To: XSI@(protected)
>To: <XSI@(protected)>, <XSI@(protected)>
>Subject: RE: Camera projections & elliptical filtering
>Date: Tue, 9 Mar 2004 07:40:50 -0500
>
>Bernard,
>Why use -c when -p does build the 12 resolutions automatically for you?
>unless you want to apply post process affects on certain resolution(s),
>which may cause problem during resolution interpolation in the elliptical
>filtering computation.
>
>Dave
>
> -- --Original Message-- --
> From: owner-xsi@(protected) on behalf of Bernard Lebel
> Sent: Tue 09/03/2004 6:22 AM
> To: XSI@(protected)
> Cc:
> Subject: Re: Camera projections & elliptical filtering
>
>
>
> 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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