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Here's my contribution to the teddy-bear collection. The teddy is from the
Moray site (thanks for the pointer, Ken) and the fur is my doing. It's kinda
sparse, but I didn't want a long render (this one was ~30 minutes at 640X480
AA 0.3 and took 69MB of memory)
I will now post the first version of my fur generator to text.scene-files.
Note that it requires the Superpatch.
Comments, suggestions and questions are welcome!
Margus
Post a reply to this message
Attachments:
Download 'Teddy2.jpg' (89 KB)
Preview of image 'Teddy2.jpg'
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Margus Ramst wrote:
>
> Here's my contribution to the teddy-bear collection. The teddy is from the
> Moray site (thanks for the pointer, Ken) and the fur is my doing. It's kinda
> sparse, but I didn't want a long render (this one was ~30 minutes at 640X480
> AA 0.3 and took 69MB of memory)
> I will now post the first version of my fur generator to text.scene-files.
> Note that it requires the Superpatch.
> Comments, suggestions and questions are welcome!
>
> Margus
>
> [Image]
Super!
This is really (photo)realistic! More and more posts in this NG seem to
deserve place in "Hall-Of-Fame" (including this one) and pushing CG
limits quite far. I have "The Book of CG" ("Computer Graphics,
Principles and Practice" by Foley, Dam, Feiner, Hughes) and I remember,
that when I bought it (3-4 years ago) then I looked at the pics in this
book and thought "Wow". Now most of the RT techniques, described there,
could be used in PovRay and pictures in that book seem to be really
primitive.
Suggestion: use "back-hair culling" - don't create those fur hairs,
which are not seen. I don't know, whether this is done already and how
hard is to do this, but it may provide more hair for camera direction.
Anyway, for this picture it is quite enough, much more won't add
anything (IMHO).
Post a reply to this message
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This one looks good !
I thought that fur could only be rendered through macros !
I am eager to take a look at your script.
> Here's my contribution to the teddy-bear collection. The teddy is from the
> Moray site (thanks for the pointer, Ken) and the fur is my doing. It's kinda
> sparse, but I didn't want a long render (this one was ~30 minutes at 640X480
> AA 0.3 and took 69MB of memory)
> I will now post the first version of my fur generator to text.scene-files.
> Note that it requires the Superpatch.
> Comments, suggestions and questions are welcome!
>
> Margus
>
> [Image]
Post a reply to this message
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>This one looks good !
>
>I thought that fur could only be rendered through macros !
>
<ahem...> It _is_ a macro. 2 macros, actually.
But fur can also be modelled with media - see the post "Did someone say
fur?" by Thomas Willhalm.
Margus
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Vahur Krouverk wrote in message <36E19E92.E46E008F@fv.aetec.ee>...
>
>Super!
>Suggestion: use "back-hair culling" - don't create those fur hairs,
>which are not seen. I don't know, whether this is done already and how
>hard is to do this, but it may provide more hair for camera direction.
It should be possible and potentially very useful. Right now I see 2
problems:
1) reflections may show bald ares;
2) you should see some hairs sprouting from areas that are outside the
camera's FOV (esp. with long hairs);
How to deal with these, I don't know. Suggestions?
Margus
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Well, what I meant is that I thought that fur could be created with a
special feature of Superpatch.
> >This one looks good !
> >
> >I thought that fur could only be rendered through macros !
> >
>
> <ahem...> It _is_ a macro. 2 macros, actually.
> But fur can also be modelled with media - see the post "Did someone say
> fur?" by Thomas Willhalm.
>
> Margus
Post a reply to this message
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I'd be happy to work with you on it. Actually I have a few ideas.. the
first being to add a "culling" keyword (ie you know there is a mirror
somewhere, so you need all the hair) or perhaps to give the vector to
the mirror and calculate off of both. The other is to add a margin to
the occlusion formula. Don't occlude EXACTLY at the point where the
point is no longer visible..occlude 5 degrees further or some such.
Steve
(of course I still need to dl the super patch)
Margus Ramst wrote:
>
> Vahur Krouverk wrote in message <36E19E92.E46E008F@fv.aetec.ee>...
> >
> >Super!
>
>
> >Suggestion: use "back-hair culling" - don't create those fur hairs,
> >which are not seen. I don't know, whether this is done already and how
> >hard is to do this, but it may provide more hair for camera direction.
>
> It should be possible and potentially very useful. Right now I see 2
> problems:
> 1) reflections may show bald ares;
> 2) you should see some hairs sprouting from areas that are outside the
> camera's FOV (esp. with long hairs);
>
> How to deal with these, I don't know. Suggestions?
>
> Margus
Post a reply to this message
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On Sat, 06 Mar 1999 20:45:34 -0500, Stephen Lavedas
<swl### [at] virginia edu> wrote:
>I'd be happy to work with you on it. Actually I have a few ideas.. the
>first being to add a "culling" keyword (ie you know there is a mirror
>somewhere, so you need all the hair) or perhaps to give the vector to
>the mirror and calculate off of both. The other is to add a margin to
>the occlusion formula. Don't occlude EXACTLY at the point where the
>point is no longer visible..occlude 5 degrees further or some such.
>
>Steve
>(of course I still need to dl the super patch)
>
>
>Margus Ramst wrote:
>>
>> Vahur Krouverk wrote in message <36E19E92.E46E008F@fv.aetec.ee>...
>> >
>> >Super!
>>
>>
>> >Suggestion: use "back-hair culling" - don't create those fur hairs,
>> >which are not seen. I don't know, whether this is done already and how
>> >hard is to do this, but it may provide more hair for camera direction.
>>
>> It should be possible and potentially very useful. Right now I see 2
>> problems:
>> 1) reflections may show bald ares;
>> 2) you should see some hairs sprouting from areas that are outside the
>> camera's FOV (esp. with long hairs);
>>
>> How to deal with these, I don't know. Suggestions?
>>
>> Margus
The paper "Computing the antipenumbra of an area light source" by Seth
Teller may be useful here. Consider the mirror, etc as the area
light. The paper is at:
http://www-graphics.stanford.edu/papers/antipenumbra
Jerry Anning
clem "at" dhol "dot" com
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The mirror problem is relatively easy to overcome; a very crude approach
would be to trace a ray from all the corners of the mirror's bounding box.
If the sample point is invisible to all these rays, we can safely deduct
that the point is not visible to the mirror.
Multiple mirrors would still present a problem, but solving that wold get
too complex (parse time is an issue, too). Culling would have to be turned
off in that case.
I just downloaded the paper suggested by Jerry, I'll see if this provides a
more plausible solution...
I can't quite visualize a solution for the second problem. When the angle
between the camera ray and the surface normal is >90 degrees, the point is
not visible (provided that all normals point outwards). But how do I know
how far the point is from the nearest visible point?
The answer may be simple, but I don't have it. Perhaps you would describe
how you'd go about solving it?
Margus
Stephen Lavedas wrote in message <36E1DA3E.44410F86@virginia.edu>...
>I'd be happy to work with you on it. Actually I have a few ideas.. the
>first being to add a "culling" keyword (ie you know there is a mirror
>somewhere, so you need all the hair) or perhaps to give the vector to
>the mirror and calculate off of both. The other is to add a margin to
>the occlusion formula. Don't occlude EXACTLY at the point where the
>point is no longer visible..occlude 5 degrees further or some such.
>
>Steve
>(of course I still need to dl the super patch)
>
Post a reply to this message
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My solution was merely to increase the angle to something like >95
degrees or so until results are good. Actually, I don't think that for
your hair at least that 90 degrees is going to be enough...ie, since the
hair sticks up from the object and is visible beyond the surface. My
solution would draw excess hairs, but fewer than covering the entire
surface
Steve
Margus Ramst wrote:
>
> The mirror problem is relatively easy to overcome; a very crude approach
> would be to trace a ray from all the corners of the mirror's bounding box.
> If the sample point is invisible to all these rays, we can safely deduct
> that the point is not visible to the mirror.
> Multiple mirrors would still present a problem, but solving that wold get
> too complex (parse time is an issue, too). Culling would have to be turned
> off in that case.
> I just downloaded the paper suggested by Jerry, I'll see if this provides a
> more plausible solution...
>
> I can't quite visualize a solution for the second problem. When the angle
> between the camera ray and the surface normal is >90 degrees, the point is
> not visible (provided that all normals point outwards). But how do I know
> how far the point is from the nearest visible point?
> The answer may be simple, but I don't have it. Perhaps you would describe
> how you'd go about solving it?
>
> Margus
>
> Stephen Lavedas wrote in message <36E1DA3E.44410F86@virginia.edu>...
> >I'd be happy to work with you on it. Actually I have a few ideas.. the
> >first being to add a "culling" keyword (ie you know there is a mirror
> >somewhere, so you need all the hair) or perhaps to give the vector to
> >the mirror and calculate off of both. The other is to add a margin to
> >the occlusion formula. Don't occlude EXACTLY at the point where the
> >point is no longer visible..occlude 5 degrees further or some such.
> >
> >Steve
> >(of course I still need to dl the super patch)
> >
Post a reply to this message
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