I am interested in 3D modeling and POVRay in particular because of the strength
of the Scene Decription Language.  I am not an artist by any stretch of the
imagination and that's where I go wrong with mesh-based modeling programs like
Blender -- you quickly get to a step where you are required to tweak your
creation visually, whereas with the SDL if you can define it mathematically
then you are golden.  I can picture what I want in my head, but representing
that as a mesh is tough.  I have seen some nice pictures on IRTC that were
created with nothing but SDL.

I have created several smaller scenes with simple unions, differences, etc --
but my question is for a more complicated model, are there any texts available
that train you to see in real-world objects the spheres, partial torii,
cylinder intersected with a plane unioned with a lathed spline, etc?  As an
easy real-world example I'll use a book case -- I can take a rectangular solid
box and then remove several smaller boxes to make shelves.  That one is pretty
easy to see, but what about more complicated and irregular objects like a bird
or a space shuttle?

I suppose this is more of a general art question with applications to either
sculpting in clay or computer modeling -- but I have searched a few Barnes and
Nobles, Amazon, and several resources on the internet but cannot seem to track
down what I'm looking for, or even how to accurately phrase the question to
make a meaningful Google search.

Thanks for any help you can point me to!

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I think this is considered part of "life drawing" instruction.
Maybe something like Bridgmans's Life Drawing,
if it isn't what you want, at least it has a lot of drawings
of naked women.

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"David D" <dav### [at] dousetteorg> wrote:
>...but what about more complicated and irregular objects like a bird
> or a space shuttle?
>
> I suppose this is more of a general art question with applications to either
> sculpting in clay or computer modeling -- but I have searched a few Barnes and
> Nobles, Amazon, and several resources on the internet but cannot seem to track
> down what I'm looking for...

I do think it comes somewhat from experience--not just in CGI modeling, but from
'looking' at the world in terms of the primitives you mentioned. It's
interesting--having spent so much time with POV-Ray, I now find myself looking
at real-world objects with an almost immediate thought of "How can I make that?
 Which modeling technique is appropriate?" As the saying goes, "You know you've
been raytracing too long when..."  ;-)

The books and magazines I've seen (or bought) do describe modeling techniques,
but those techniques are usually, and unfortunately, 'application-specific'.
(Maya, 3d Studio, Form*Z, etc.) Some of the info is immediately applicable to
POV-Ray, some isn't. The newsgroups here are quite good at presenting novel
ways of going about building objects; but when it comes to an 'organic' shape,
like a bird, mesh-building does seem to be the method of choice (over CSG with
primitives.) Something like a space shuttle would most likely be a combination
of the two. It also depends on how 'real-looking' you need the object to be.

I wish I could point you to a definitive source for an answer to your basic
question, but I've never come across one.

Ken W.

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David D wrote:
> I am interested in 3D modeling and POVRay in particular because of the strength
> of the Scene Decription Language.  

Yup.


I am not an artist by any stretch of the
> imagination 

It's a new beginning



and that's where I go wrong with mesh-based modeling programs like
> Blender -- you quickly get to a step where you are required to tweak your
> creation visually, whereas with the SDL if you can define it mathematically
> then you are golden.  

True, but not absolutely true.  For regular geometric shapes these 
programs do accept numerical parameters but perhaps have differing 
levels of support for changing the parameters or producing them 
algorithmically.


I can picture what I want in my head, but representing
> that as a mesh is tough.  I have seen some nice pictures on IRTC that were
> created with nothing but SDL.

And that is one very good source.  In the early days, contestants posted 
their SDL and sifting through that stuff was how many of us learned.

Also there are some GUI modellers supporting POV style primitimes and 
exporting to POV, such as Moray or POV Lab.  You might consider using 
such a tool to play with possibilities and try and better understand 
volumetric shapes.  I am not suggesting it be a magic-bullet, final 
solution, just one ancilliary way to learn.  I don't know of any tuts 
for using these tools in the 'here's how to model a flower' sort of 
vein, though.  If there were, it would probably be the thing you want. 
(The program 'Poser' has a feature where its models can be viewed a 
block-shaped volumes, btw.)


> 
> I have created several smaller scenes with simple unions, differences, etc --
> but my question is for a more complicated model, are there any texts available
> that train you to see in real-world objects the spheres, partial torii,
> cylinder intersected with a plane unioned with a lathed spline, etc?  As an
> easy real-world example I'll use a book case -- I can take a rectangular solid
> box and then remove several smaller boxes to make shelves.  That one is pretty
> easy to see, but what about more complicated and irregular objects like a bird
> or a space shuttle?

Can't think of anything off the top of my head.  Modelling in pure 
primitives is a niche interest. (First of all, most hobbiest programs 
supporting primitives really implemented them as mesh, so up and down 
the scale, mesh has always been the thing. The interest in true 
mathematical primitives is very limited.)

I do recall a book devoted to modelling insects, and showed how to 
derive the complex shape from a set of geometric volumes. This book was 
kind of analogous to the sort of hobbiest, 'how to draw' books that you 
may have in mind.  These how to draw books, aimed at the amateur market, 
would illustrate some process of stepping through the visualizing of a 
complex organic structure, such as a bird or horse, by first roughing 
out the shape as basic geometric volumes.  This idea of course has its 
precursor throughout the history of art.  But that is a whole other 
diversion, except to point out that you are not wrong in hoping to find 
some sort of standard codex for breaking doen complex structures into 
simpler volumes.  It is just that in the digital world at large, this is 
usually played out as mesh modelling.


Of course mesh modelling, and this is particularily important to its 
detractors, is a bit like drawing in that it deals with surfaces of 
shapes, complex shapes to be sure, but just the surface.  One whole 
appeal to virtual modelling is the potential for constructing complex 
shapes by piecing togther the internal or component structure that 
results in the outward complexity.  This is more often the purview of 
the primitives modeler. While this also has its analogue in the history 
of art, (such as George Stubbs anatomizing horses,) it dovetails nicely 
with design fields like engineering and architecture or scientific 
fields like biology and chemistry.




> 
> I suppose this is more of a general art question with applications to either
> sculpting in clay or computer modeling -- but I have searched a few Barnes and
> Nobles, Amazon, and several resources on the internet but cannot seem to track
> down what I'm looking for, or even how to accurately phrase the question to
> make a meaningful Google search.
> 

Visualizing complex volumes as a sequence of simpler volumes is one 
aspect.  But the world of CSG is also much about clever ways to use 
'differences' 'intersections' and 'scaling' of shapes to produce complex 
surfaces.  I do not know of any book treating this.  There have been 
over time various attempts to regularize these tecniques into macros and 
include files.  You should search through the resources and ng's here 
(esp the binaries postings) for these efforts, not only to use, but to 
examine and learn methods.

Finally, breaking down complexity, or clever techniques for welding 
seams, can still only go so far.  In the end mathematical primities will 
impose a mathematical look.  The most exciting visual artists  transform 
the look imposed by their materials into a comvincing illusion or 
personal statement through the intagible quality described by the word 
'style'.  In part it involves somehow harnessing the most intractable 
qualities of the materials used rather than overcoming them.  There are 
many clever ways to do this and many more to be discovered.  Often it 
involves creating a very complete and analogue sense of reality withing 
the parameters of the material.  Recently, for instance, there have been 
some great postings here from people working within the 'childhood 
world' of Lego models.

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Sometimes it can be helpful (or at least somewhat entertaining) just to 
sit down with a simple object and a ruler and try making the shape.  For 
example, grab a soda can.  It's a cylinder, right?  You can easily 
measure the dimensions of the cylinder and render it.

But then you look at it again.  Well, actually, it's a lot more than 
just a cylinder.  There's a sort of stretched-up torus around the top, 
and that odd-shaped indentation under the pull tab--whoa, there's a pull 
tab!  And so on.  You just do one piece at a time--make that piece look 
right, and then move on to another piece.

When you're just working on the shape, it can be useful to use a shiny 
plastic texture (like the shiny red plastic in the Help file tutorials). 
  That will give you a good idea of the shape without any textural 
distractions.  Once you've got something that looks sort of right, 
though, you'll want to make a textured version (which is where Warp's 
tutorial about improving scenes becomes really useful; it's got some 
nice examples of textures and lighting that could help transform that 
red plastic soda can into something realistic).

A few years back, I sat down with a stand magnifier (you know, the 
Double-Barreled Roach Clip With Solar Lighter) and started measuring and 
coding.  About 1500 lines later, I actually had something I liked enough 
to put in an IRTC entry.  It didn't win or anything, but I was pretty 
happy with it.  ;)

Well, anyway, hope that helps a little.  I've had the flu for about a 
week and am feeling a little brain-damaged, so hope this isn't too 
incoherent.  ;)

--Sherry Shaw


-- 
#macro T(E,N)sphere{x,.4rotate z*E*60translate y*N pigment{wrinkles scale
.3}finish{ambient 1}}#end#local I=0;#while(I<5)T(I,1)T(1-I,-1)#local I=I+
1;#end camera{location-5*z}plane{z,37 pigment{granite color_map{[.7rgb 0]
[1rgb 1]}}finish{ambient 2}}//                                   TenMoons

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Thanks to all for the advice!

Sherry -- I would be very interested in seeing what you came up with for an IRTC
entry using this method, particularly if it is from early in your development
with POV-Ray.  Can you post a link?

What you described with taking a physcial object and converting it into CSG a
step at a time is exactly what I would like to do.  I have physical models of
different things around the house that I would love to CSG-ify, and after that I
have several scanned diagrams and schematics for various machines and devices
that it would be fun to convert into (first static, then animated) models.

Sherry Shaw <ten### [at] aolcom> wrote:
> Sometimes it can be helpful (or at least somewhat entertaining) just to
> sit down with a simple object and a ruler and try making the shape.  For
> example, grab a soda can.  It's a cylinder, right?  You can easily
> measure the dimensions of the cylinder and render it.
>
> But then you look at it again.  Well, actually, it's a lot more than
> just a cylinder.  There's a sort of stretched-up torus around the top,
> and that odd-shaped indentation under the pull tab--whoa, there's a pull
> tab!  And so on.  You just do one piece at a time--make that piece look
> right, and then move on to another piece.
>
> When you're just working on the shape, it can be useful to use a shiny
> plastic texture (like the shiny red plastic in the Help file tutorials).
>   That will give you a good idea of the shape without any textural
> distractions.  Once you've got something that looks sort of right,
> though, you'll want to make a textured version (which is where Warp's
> tutorial about improving scenes becomes really useful; it's got some
> nice examples of textures and lighting that could help transform that
> red plastic soda can into something realistic).
>
> A few years back, I sat down with a stand magnifier (you know, the
> Double-Barreled Roach Clip With Solar Lighter) and started measuring and
> coding.  About 1500 lines later, I actually had something I liked enough
> to put in an IRTC entry.  It didn't win or anything, but I was pretty
> happy with it.  ;)

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I am coming late into the debate and most has been said already. Just from 
my personal experience, I really learned to model in CSG in my early days, 
by heavily using Moray. Nowadays you could also consider Bishop3D I suppose. 
It gave me the clear understanding about how the world could be turned into 
a (complex) bunch of simple primitives. From there, I gradually shifted to 
the use of meshes, which I favour nowadays, without entirely abandoning CSG 
of course. Wings3D is an excellent introduction to that world.

And, it goes without saying, I learned from looking at what others had 
achieved, and asking stupid questions. These forums are magnificent for both 
:-)

Thomas

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David D wrote:
> Can you post a link?

Sure!

http://www.irtc.org/ftp/pub/stills/2004-04-30/sks_bust.jpg (picture)
http://www.irtc.org/ftp/pub/stills/2004-04-30/sks_bust.txt (description)
http://www.irtc.org/ftp/pub/stills/2004-04-30/sks_bust.zip (the stand 
magnifier code and a sample scene)

One of the most fun things I've worked on this way was a margarita 
glass, the kind where the stem looks like a cactus.  ;)  (The cactus 
"arms" are blob objects.)  Haven't used it in any "real" pictures yet, 
but maybe when the IRTC returns...

--Sherry Shaw


-- 
#macro T(E,N)sphere{x,.4rotate z*E*60translate y*N pigment{wrinkles scale
.3}finish{ambient 1}}#end#local I=0;#while(I<5)T(I,1)T(1-I,-1)#local I=I+
1;#end camera{location-5*z}plane{z,37 pigment{granite color_map{[.7rgb 0]
[1rgb 1]}}finish{ambient 2}}//                                   TenMoons

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"Thomas de Groot" <tDOTdegroot@interDOTnlANOTHERDOTnet> wrote:
> And, it goes without saying, I learned from looking at what others had
> achieved, and asking stupid questions. These forums are magnificent for both
> :-)

You know you've been raytracing too much...
    ... when you run out of stupid questions to ask on POV :)

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"clipka" <nomail@nomail> schreef in bericht 
news:web.49be650ebc77386489022530@news.povray.org...
> "Thomas de Groot" <tDOTdegroot@interDOTnlANOTHERDOTnet> wrote:
>> And, it goes without saying, I learned from looking at what others had
>> achieved, and asking stupid questions. These forums are magnificent for 
>> both
>> :-)
>
> You know you've been raytracing too much...
>    ... when you run out of stupid questions to ask on POV :)


Now, this is something to ponder very deeply indeed....  :-)

Thomas

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