#Splines vs. Polys
16 messages in this thread
Richard,
I used to think the same thing until I tried to work on some Viewpoint
models. If you want anything with a lot of detail or realism, trying to work on
a polygon model that has been converted to splines in AM is pointless. (I
should say "pointed", considering the amount of control points there are in a
detailed conversion.) There are supposed to be Boolean cutters added to AM in
Version 3. If they also add a degree selection for Lathing and some lofting,
the modeler will be extremely powerful. Also, over in the Autodesk forum, and
in the forums for 3D images and animations both on Compuserve and AOL, too many
of the users of AutoCad and 3D Studio and some of the users of other packages
seem to be more interested in what you might call "posing". There is not a lot
of attention paid to detail. Quality takes time, but too many users are more
interested in cranking out images and anims to take the time to make them
detailed or accurate.
I've downloaded a number of .DXF files, images and anims just to check out
what folks are doing with other things. I was so disappointed that I decided to
create my own version of one of the most popular models that people upload –
the TIE Fighter from Star Wars. I created a TIE and a TIE Interceptor and have
uploaded a few images in the SF Fantasy Media Forum, and in the Graphics and
Animation area on AOL. I got a lot of positive feedback, and even mild
disbelief from a few 3DS and ACAD users for the fact that I used a spline
modeler.
The fact that there is not a lot of models available here the way there is
in the ACAD forum is simply the fault of all of the participants here. If
everyone took the time to create one simple commonplace object every 3-4 months
and upload it for general use, it wouldn't take long for us to have a huge
selection of objects. The drawback is that some people would refuse to
contribute while availing themselves of others' contributions. Also,
contributions would come from a wide variety of skill levels, and some objects
would be more detailed and realistic than others, but you wouldn't find out
until they were downloaded.
Originally, I also wished for a polygon modeler added to AM, but I have
since given that up. Hash wants to move AM into the future, and it is going to
pay off big in the long run not to hang on to old technology. Besides, if they
added a polygon modeler, how many of us would find it too tempting to use it
instead of creating a spline model? I know there are times that I would, and
that would take away from me developing my spline modeling skills. It may be a
longer, harder road to travel at the moment, but I had to make the decision to
use splines instead of polygons. Force yourself to give up polygons unless
absolutely necessary, and in a while I think you won't really miss them at all.
I know that I don't.
Michael S. Flynn
Michael;
Sorry about butting into the thread, but could you tell me what the pros and
cons of the spline and polygon modelers are? I'm thinking about purchasing
some 3D animation/raytracing software, and need some experienced advice about
the tradeoff between the two types.
Thanks in advance.
Very Respectfully,
Chad Brivkalns
75541,2406
Chad,
Please feel free to butt in any time. The following are my personal views as
an A.M.beginner. The Hash people will probably have something to say and
they're usually proved right in the long run.
I'm sure spline modellers are potentially much better than polygon-based tools,
once you get the hang of them. For instance, you can get a reasonable-looking
human figure in a 30K file, the equivalent DXF would be 100's of K and would
still look faceted in most modellers.
Undoing bad modelling can be tricky with splines though. It's a bit like
unpicking that thing in the middle of a golf ball. Watch out for flying rubber
bands!
So if you're into modelling your own stuff, go for splines. A.M. and P.M. are
the only products at the affordable end of the market which uses them as far as
I know. (I think Wavefront has a spline option if you've got $20K or whatever
to spare.) But if you want to get going quickly as an animation director there
isn't much ready-made spline stuff around but hopefully there will be soon.
Richard
Chad, the big difference between spline modelers and polygons is spline/patch
modelers create easily animatable organic models. Polygons simply can't do
this! If you wan't spaceships and buildings, Polygons are fine…. trees,
plants or people are much easier with patches AND you can do the other stuff
too!
Steve, Hash Inc.
Michael,
Thanks for your reply. Basically I agree with everything you say. I suppose
my frustration stems from the fact that I am more interested in directing
action than in 3D modelling.
Consider a live-action film director. He is an artist too and he doen't build
his props from scratch, he buys (or borrows or steals) them – or hires a
carpenter. He doesn't build his actors either, unless his name is
Frankenstein, he hires them.
I agree with you about uploads. Just as soon as I have modelled anything more
interesting than a bouncing potato, I'll upload it. I wonder if it is possible
to implement a one-for-one or kbyte-for-kbyte upload/download policy in a CIS
forum? Then maybe the Hash boys could throw in some of their (obviously very
precious) spline models to get things going.
I still think a polygon editor would be a good idea for the next A.M. It
seems such a shame to waste all the good 3D data there is around. I think
sensible conversion to splines needs human input. The interface would be
similar to SCULPT, but the left window would be for the DXF (with FAST polygon
handling), the right would be for the SEG. Users would select a series of
points in the DXF window representing what looks like a good spline path. A
button would convert this to a spline in the SEG window using some kind of
best-fit routine. I know it's laborious but so is any kind of definitive 3D
modelling. The result would not be the best use of splines but would be
infinitely better than the big heap of two-point splines you get with the
current import or the DXF2SEG converter. (If I was any kind of programmer I
would take a shot at it myself).
Nothing would promote A.M. better than more (good) ready-made spline models.
Richard
Richard…. Hash Inc. will be releasing every model we've ever built on a CD
with texture maps, image maps and motion files later this year… This will go
out free or for a very nominal charge to all registered users who ask for it!
Steve, Hash Inc.
Steve…
Oooh, I want that CD yesterday! Glad to hear it and I look forward
to ordering it!
Kevin
Steve,
Looking forward to it!
YEA!!!!, when available let me know!!!
– Robb Canfield, Written 04-Jan-1995 @ 22:51:05
Using: Windows NavCIS PRO 1.25
>Richard…. Hash Inc. will be releasing every model we've ever built on a CD
with >texture maps, image maps and motion files later this year… This will go
out free or >for a very nominal charge to all registered users who ask for it!
> Steve, Hash Inc.
Steve Is it to soon to ask now???
Grady III
Richard…
You may already know this, but there are some primitves (spheres,
cubes, etc.) in the Hash Library here on CI$. They are good starting
points to build things you may need. There are also models included
with Animation Master that you can experiment with.
You probably already know that, but just in case you didn't.. You can
also order basic fonts (there are some samples here I think of one
person's efforts) and from Branded Research.
Kevin
Kevin,
Thanks, I've got the primitives.
Richard,
I don't know how polygon-to-spline conversion works, but it appears that a
point-to-point basis is used. I wonder if it would be practicle instead to do
an Object A-to-Object B conversion of the surface that is represented by the
points in a polygon model to the minimum number of points required to achieve
the same surface in a spline model. If there was a conversion routine like
that, I think it would accelerate the move from polygon modeling to spline
modeling.
Michael S. Flynn
Michael,
It should be possible, but I suppose you would need to set some tolerance for
the match between the polygon and spline surfaces, otherwise the computer would
grind away for a long time trying to achieve convergence.
The easiest thing to implement would be a manual selection of points (maybe a
string of two-point spline endings, as you get in DXF imports) followed by
pressing some kind of "define as spline" button. There's no real difference
between this way of defining a spline and the way a multiple-point spline is
built up currently using the mouse in SCUPTURE.
It's great just talking about these features but probably a major pain to code
them!
Richard
Richard,
it must be clear by now that I am a new owner of AM, I hope to load it
into my system tomorrow, or maby next week.
I can't say I agree with your views about pol-ee-gon vs Splines, but I do
think that your points have a great deal of merrit.
maby We can use me as a test case. As a first time user and owner I will
start uploading files if I can figure out how to do that to CIS from my
internet account??? I am about as brain dead when it comes to using command
shells and scripts to do things….(?).
My gut feeling is that the actual usefulness of poly and splines is a
matter of attitude and effort+some skill.
Hope you don't mind my intrusion…:-) Lee
> I used to think the same thing until I tried to work on some Viewpoint
models. >If you want anything with a lot of detail or realism, trying to work
on a polygon >model that has been converted to splines in AM is pointless. (I
should say >"pointed", considering the amount of control points there are in a
detailed >conversion.)
This is true, and the time it takes to load isn't pretty either…
> The fact that there is not a lot of models available here the way there is
in the >ACAD forum is simply the fault of all of the participants here. If
everyone took the >time to create one simple commonplace object every 3-4
months and upload it for >general use, it wouldn't take long for us to have a
huge selection of objects. The >drawback is that some people would refuse to
contribute while availing >themselves of others' contributions. Also,
contributions would come from a wide >variety of skill levels, and some objects
would be more detailed and realistic than >others, but you wouldn't find out
until they were downloaded.
I would be willing to contribute a few "general" objects for use. I think the
reason there are not more "general" objects uploaded here is that poeple
instantly try to create original character. I know did.. I did the little alien
animation I uploaded… I would be willing to upload my toothpaste and
toothbrush segments. The only reason I never uploaded it is because it was my
first feeble attempt, and I didn't think it would be useful for anyone… So
where should I upload some of my stuff???
>Michael S. Flynn
I remember when you kinda ribbed me about questioning the need for booleen
operation in animation master. Today I apologize, I was tryin to create a
little simple concave in an object, and It just would curve right…And I
realized if I could subtract a oval or shpere..wallah… Man.. Next time I'm
gonna think before I type.. 🙂
Grady III