 | | | Camera projections & elliptical filtering | Camera projections & elliptical filtering 2004-03-09 - By Harry Bardak
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hi bernard,
i didn't get the time to investigate more "-c" option of imf_copy. To be
honest, i planed that to see more the next week.
So I did some test this week end with "-p" + elliptical filtering and i get
very good, very smooth on texture, as expected in the Mr's docs.
You have to check these points :
- Is the filter applied on alpha too ?
- Are your layer premultiplied ( in case of you use bitmap ) ? In this case
try to umpremult them.
- Are there any way to do the layer blending before xsi ( i mean in fxtree,
or photoshop ... ) ?
Hope this help. A bientot.
Harry.
-- -- Original Message -- --
From: "Bernard Lebel" <atyss4si@(protected)>
To: <XSI@(protected)>
Sent: Tuesday, March 09, 2004 12:22 PM
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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