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If one uses blobs in povray to make a hand or a body with legs, one can
run into one of several problems:
1. The fingers or legs may web together when they get close if the two
limbs are in the same "blob;" OR
2. The joint may not look that natural if the two limbs are in different
blobs.
I have heard that more advanced modelling packages have a way to set up
hierarchical relationships between the limbs. For example, the elements
that make up the fingers may blob with the wrist and elements of the
same finger, but not elements of other fingers.
_________________
Greg M. Johnson
"The program I just wrote is a patentable, new technology," said the CS
to the Fellow of the Materials Research Society.
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Yeah. I also want this. I have a project where I want to use blobs, but the
darn blobs 'blob' with the wrong ones. It would be nice if you could for
instance, declare blob element 1 as, say, A, and elements two and three as B
and C. Then you could give an 'interactions' list. B for A, C for B and B
for C, you see?
(A)===(B)
//
(C)
Forgive the crude ascii art.
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You're wishing for NURBS modelling I believe. Think this is actually
just fancy meshes. 'blob' is of a two-fold design being
attractive/repulsive and there are possible ways to add both, though
messy as heck and not always workable for complex things, especially
animated shapes I would think.
TonyB wrote:
>
> Yeah. I also want this. I have a project where I want to use blobs, but the
> darn blobs 'blob' with the wrong ones. It would be nice if you could for
> instance, declare blob element 1 as, say, A, and elements two and three as B
> and C. Then you could give an 'interactions' list. B for A, C for B and B
> for C, you see?
>
> (A)===(B)
> //
> (C)
>
> Forgive the crude ascii art.
--
omniVERSE: beyond the universe
http://members.aol.com/inversez/homepage.htm
mailto:inv### [at] aol com?Subject=PoV-News
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No, he wants blobs... I think (and I'm pretty sure I understand this) that
what he is trying to say is to have some blobs only interact with certain
blobs...
Get it? NURBS has nothing to do with this...
Anyway, back to the subject. There are some plugs-ins for MAX which do very
advanced "skinning" based on meta blobs, only the blobs are not standard
blobs, they are kind of elastric strands of blobs. Using this method it's
easy to make muscles etc etc
--
Lance.
---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone
For a totally different experience, visit my Chroma Key Website:
Colorblind - http://www.fortunecity.com/skyscraper/parallax/359/colorblind
Bob Hughes wrote in message <37250E22.1404C30E@aol.com>...
>You're wishing for NURBS modelling I believe. Think this is actually
>just fancy meshes. 'blob' is of a two-fold design being
>attractive/repulsive and there are possible ways to add both, though
>messy as heck and not always workable for complex things, especially
>animated shapes I would think.
>
>
>TonyB wrote:
>>
>> Yeah. I also want this. I have a project where I want to use blobs, but
the
>> darn blobs 'blob' with the wrong ones. It would be nice if you could for
>> instance, declare blob element 1 as, say, A, and elements two and three
as B
>> and C. Then you could give an 'interactions' list. B for A, C for B and B
>> for C, you see?
>>
>> (A)===(B)
>> //
>> (C)
>>
>> Forgive the crude ascii art.
>
>--
> omniVERSE: beyond the universe
> http://members.aol.com/inversez/homepage.htm
> mailto:inv### [at] aolcom?Subject=PoV-News
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Yep, okay, I know very little of things outside of POV-Ray and not
enough even now of POV.
Thing I was getting at though is it's highly unlikely to get a good
combination of blobs to work right for animations, a still image would
be possible much more so than animation anyhow.
The "feature request" sounds very much like a combination of positive
and negative strength blobs working in conjunction. Better yet, a
"directional" type of thing, inside/outside separated influences instead
of both at once acting on each and every blob element.
Lance Birch wrote:
>
> No, he wants blobs... I think (and I'm pretty sure I understand this) that
> what he is trying to say is to have some blobs only interact with certain
> blobs...
>
> Get it? NURBS has nothing to do with this...
>
> Anyway, back to the subject. There are some plugs-ins for MAX which do very
> advanced "skinning" based on meta blobs, only the blobs are not standard
> blobs, they are kind of elastric strands of blobs. Using this method it's
> easy to make muscles etc etc
>
> --
> Lance.
>
> ---
> For the latest 3D Studio MAX plug-ins, images and much more, go to:
> The Zone - http://come.to/the.zone
> For a totally different experience, visit my Chroma Key Website:
> Colorblind - http://www.fortunecity.com/skyscraper/parallax/359/colorblind
> Bob Hughes wrote in message <37250E22.1404C30E@aol.com>...
> >You're wishing for NURBS modelling I believe. Think this is actually
> >just fancy meshes. 'blob' is of a two-fold design being
> >attractive/repulsive and there are possible ways to add both, though
> >messy as heck and not always workable for complex things, especially
> >animated shapes I would think.
> >
> >
> >TonyB wrote:
> >>
> >> Yeah. I also want this. I have a project where I want to use blobs, but
> the
> >> darn blobs 'blob' with the wrong ones. It would be nice if you could for
> >> instance, declare blob element 1 as, say, A, and elements two and three
> as B
> >> and C. Then you could give an 'interactions' list. B for A, C for B and B
> >> for C, you see?
> >>
> >> (A)===(B)
> >> //
> >> (C)
> >>
> >> Forgive the crude ascii art.
> >
> >--
> > omniVERSE: beyond the universe
> > http://members.aol.com/inversez/homepage.htm
> > mailto:inv### [at] aolcom?Subject=PoV-News
--
omniVERSE: beyond the universe
http://members.aol.com/inversez/homepage.htm
mailto:inv### [at] aolcom?Subject=PoV-News
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I am talking about blobs. My IRTC entry, "Lane changing incident at the
Pan-Compositional Games," was made of blobs of human running figures. The MPG is
at:
http://oz.irtc.org/ftp/pub/anims/1998-10-15/lane.mpg
And a JPG is at:
http://irtc.org/anims/1998-10-15/lane.jpg
My runners are not in dresses but their legs "blob" together when they get close
to each other. I wanted a feature that would say,
blob{
threshhold 0.4
sphere {center_1, radius, strength, [list_of_subblobs]}
sphere {center_2, radius, strength, [list_of_subblobs]}
sphere {center_3, radius, strength, [list_of_subblobs]}
etc.
}
Where [list_of_subblobs] is a list of ordinal numbers, say [1,3,4], where each
number corresponds to a different area on the big blob to blob with.
Each blob component would have a list of subblobs that it would choose to blob
with. For example, the blob components for the right leg would blob with each
other and the but but not the left leg. The buttock collection or the whole torso
could be sub-blob #1, the right leg sub-blob #2, the left leg sub-blob #3, etc.
Some advanced BLOB MODELLERS, or META-BALL MODELLERS, have this feature, according
to the book Digital Character Animation.
Bob Hughes wrote:
> Yep, okay, I know very little of things outside of POV-Ray and not
> enough even now of POV.
> Thing I was getting at though is it's highly unlikely to get a good
> combination of blobs to work right for animations, a still image would
> be possible much more so than animation anyhow.
> The "feature request" sounds very much like a combination of positive
> and negative strength blobs working in conjunction. Better yet, a
> "directional" type of thing, inside/outside separated influences instead
> of both at once acting on each and every blob element.
>
> Lance Birch wrote:
> >
> > No, he wants blobs... I think (and I'm pretty sure I understand this) that
> > what he is trying to say is to have some blobs only interact with certain
> > blobs...
> >
> > Get it? NURBS has nothing to do with this...
> >
> > Anyway, back to the subject. There are some plugs-ins for MAX which do very
> > advanced "skinning" based on meta blobs, only the blobs are not standard
> > blobs, they are kind of elastric strands of blobs. Using this method it's
> > easy to make muscles etc etc
> >
> > --
> > Lance.
> >
> > ---
> > For the latest 3D Studio MAX plug-ins, images and much more, go to:
> > The Zone - http://come.to/the.zone
> > For a totally different experience, visit my Chroma Key Website:
> > Colorblind - http://www.fortunecity.com/skyscraper/parallax/359/colorblind
> > Bob Hughes wrote in message <37250E22.1404C30E@aol.com>...
> > >You're wishing for NURBS modelling I believe. Think this is actually
> > >just fancy meshes. 'blob' is of a two-fold design being
> > >attractive/repulsive and there are possible ways to add both, though
> > >messy as heck and not always workable for complex things, especially
> > >animated shapes I would think.
> > >
> > >
> > >TonyB wrote:
> > >>
> > >> Yeah. I also want this. I have a project where I want to use blobs, but
> > the
> > >> darn blobs 'blob' with the wrong ones. It would be nice if you could for
> > >> instance, declare blob element 1 as, say, A, and elements two and three
> > as B
> > >> and C. Then you could give an 'interactions' list. B for A, C for B and B
> > >> for C, you see?
> > >>
> > >> (A)===(B)
> > >> //
> > >> (C)
> > >>
> > >> Forgive the crude ascii art.
> > >
> > >--
> > > omniVERSE: beyond the universe
> > > http://members.aol.com/inversez/homepage.htm
> > > mailto:inv### [at] aolcom?Subject=PoV-News
>
> --
> omniVERSE: beyond the universe
> http://members.aol.com/inversez/homepage.htm
> mailto:inv### [at] aolcom?Subject=PoV-News
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On Tue, 27 Apr 1999 09:34:44 -0400, Greg M. Johnson wrote:
>Where [list_of_subblobs] is a list of ordinal numbers, say [1,3,4], where each
>number corresponds to a different area on the big blob to blob with.
>
>Each blob component would have a list of subblobs that it would choose to blob
>with. For example, the blob components for the right leg would blob with each
>other and the but but not the left leg. The buttock collection or the whole torso
>could be sub-blob #1, the right leg sub-blob #2, the left leg sub-blob #3, etc.
This doesn't make any sense when you think about a blob as a mathematical
construct. Remember, a blob is just the isosurface of a scalar field gotten
by adding the strengths due to each blob component at the point in question.
If you're at a point somewhere between two "non-interacting" blob elements,
how are you supposed to determine which blob elements to consider in the
calculation and which to not consider? I can see a way to do it if you had
disjoint sets of non-interacting blob elements, but you're saying you want
A to interact with B, and B to interact with C, but you don't want A to
interact with C. Well, it doesn't work that way. If it did, you'd have a
big problem in the vicinity of B, because there are multiple choices for
the equation and none of them are "right." (A+B, B+C, or A+B+C?)
When it comes down to it, this is a modeler problem rather than a renderer
problem. To model what you want, you just have to do this:
union {
blob {
(element-collection A)
(element-collection B)
}
blob {
(element-collection B)
(element-collection C)
}
}
Yes, there's some duplication there. If you have a lot of duplicated elements,
I would suggest using a macro until POV allows you to include a blob into
another blob by reference.
Okay, I hear the whining about the possiblity of a visible seam between the A-B
blob and the B-C blob already. Well, what did you expect? The seam is a direct
consequence of the multiplicity of solutions near point B. The only way to get
rid of that seam is to allow A and C to interact!
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In article <372### [at] geocitiescom> , "Greg M. Johnson"
<gre### [at] geocitiescom> wrote:
> I am talking about blobs. My IRTC entry, "Lane changing incident at the
> Pan-Compositional Games," was made of blobs of human running figures. The MPG
> is at: http://oz.irtc.org/ftp/pub/anims/1998-10-15/lane.mpg And a JPG is at:
> http://irtc.org/anims/1998-10-15/lane.jpg
>
> My runners are not in dresses but their legs "blob" together when they get
> close to each other. I wanted a feature that would say,
You can use a trick:
If the strength of two blobs does not interact (i.e. they are far enough
away from each other) you can remove one of the blobs without changing the
result. You can use this fact to do some tricks with CSG: Construct a
complete body with blobs, then copy each arm and leg blobs. Use for example
a plane to clip away the interacting parts of the main body and do it the
other way around for each arm and leg. It is a lot of testing usually, but
it works (not perfect, but better than having them interact).
Thorsten
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I think I understand your mathematical objection. The book Digital Character
Animation suggests that there are packages that can do this.
Are they based on some other algorithm? Are they merely based on the union method you
are describing? Could a version of POV work out this union method "automatically"
using the syntax I proposed? Is it worthwhile?
Ron Parker wrote:
> This doesn't make any sense when you think about a blob as a mathematical
> construct. Remember, a blob is just the isosurface of a scalar field gotten
> by adding the strengths due to each blob component at the point in question.
>
> If you're at a point somewhere between two "non-interacting" blob elements,
> how are you supposed to determine which blob elements to consider in the
> calculation and which to not consider? I can see a way to do it if you had
> disjoint sets of non-interacting blob elements, but you're saying you want
> A to interact with B, and B to interact with C, but you don't want A to
> interact with C. Well, it doesn't work that way. If it did, you'd have a
> big problem in the vicinity of B, because there are multiple choices for
> the equation and none of them are "right." (A+B, B+C, or A+B+C?)
>
> When it comes down to it, this is a modeler problem rather than a renderer
> problem. To model what you want, you just have to do this:
>
> union {
> blob {
> (element-collection A)
> (element-collection B)
> }
> blob {
> (element-collection B)
> (element-collection C)
> }
> }
>
> Yes, there's some duplication there. If you have a lot of duplicated elements,
> I would suggest using a macro until POV allows you to include a blob into
> another blob by reference.
>
> Okay, I hear the whining about the possiblity of a visible seam between the A-B
> blob and the B-C blob already. Well, what did you expect? The seam is a direct
> consequence of the multiplicity of solutions near point B. The only way to get
> rid of that seam is to allow A and C to interact!
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