#Opacity
23 messages in this thread
A funny thing happened to me on the way to creating an example…
Is it not possible to get true transparency with an opacity map on a material
that doesn't use a texture map? Even with total black for opacity (yes, I
copied it over to the shininess slot as well), when I have a background that
isn't black I notice a ghost outline of a material that doesn't have a texture
map (no, it isn't the shininess showing — that looks completely different).
With a texture map, Opacity works as I always assumed it did (just goes to show
you how little I've used Opacity). I tried several examples, even the one on
the Inside 3DS Disk, and they all exhibit this "problem."
What is the state of your NEW-SUBTRACTIVE-TRANSPARENCY setting?
– G
You're right — that was certainly the majority of it. However, there were two
other problems then, and it raises a few questions:
1) What about the NEW-SUBTRACTIVE-TRANSPARENCY? I turned it on because the
3DS.SET file implied that it would be better. What do I lose by having it off?
2) In order to get the effect to work, I also needed to turn Filter Maps off.
What do I lose by doing this? (With them on, I got an edging effect along the
transparent portion of the object).
3) Even after all the above, the end of the object (a long tube lofted with
mapping coordinates) appeared. The only way I could figure out to get rid of
it was to select the faces at the end and deleting them. The end of the tube
directly faced the camera, and rendered as solid (but not with the normal
color) regardless of the state of the opacity map. Any ideas about this one?
After I did the above, everything was fine, but I thought I had better get
answers so I can summarize all this in a text file for the project (so others
won't have to go through this).
The new subtractive transparency method isn't necessarily better… it's
different. There was a big thread about it with many interesting details that
you'd find informative — hopefully Jonas or someone else can dig it up for
you.
– G
Mike, Hey, I had exactly the same thing happen. I was helping someone who
wanted to have an opacity map on a spring, and no matter what I did I could not
get the opacity map to affect the end faces of the lofted tube. I can't
remember what he ended up doing. I'd be interested in what you find out though.
DM
Regarding your items #2 and #3: I faced EXACTLY the same problem when
applying an animated opacity map to a lofted object. To me, it
appears that the map filtering wraps to the end of the map (to create
a smoother seam).
I never completely eliminated the problem, but instead used careful placement
of lights and cameras to hide the "glitch". I found that setting a texture
blur setting of 0, together with Summed Area filtering minimized the problem.
You might try the TEXTURE-SHARPEN parameter in your 3DS.SET file. It was one
of those hidden R3 set file settings. It is documented in R3HIDN.ZIP (.TXT?),
I think. Or it can be found in R4's set file.
I assume that you are using a flic for your animated map. Perhaps you can
create a set of TGA's to produce the effect and use an IFL for precise control
of the frames. You may get some better results.
– Dave
Thanks for your suggestions, David. Actually, I was really trying to just
create a generic example for others — when I've had to do this myself either
the end wasn't a problem (it was off camera) or I selected and deleted the
face(s) at the end to achieve the effect. I just assumed at the time I didn't
know what I was doing, but got the desired results.
I really think the "end" effect is a bug of sorts — perhaps a rather esoteric
bug to be sure, but one nonetheless given the way things are supposed to work.
But as my major concern right now is modeling I think I'll worry about other
things.
Mike,
>> Is is not possible to get true transparency with an opacity map on a
material that doesn't use a texture map? <<
I'm not sure what the point is to having total transparency with an opacity map
but typically I morph from one material to another, so that if I have an object
with 100% transparency (no map) I morph to a target with an opacity map which
has some opaqueness and all works fine…
FWIW
John
>I'm not sure what the point is to having total transparency with an opacity
map >but typically I morph from one material to another
If you want to look at SPOOL.ZIP (whenever it's merged) you'll see why an
opacity map is the only tool to use there. It's the same concept as the
handwriting example in Inside 3D Studio. Morphing just isn't an option here.
>> If you want to look at SPOOL.ZIP …. <<
Thanks Mike I will. I've done handwriting with the opacity map technique and it
hasn't been a problem, but there's always the unique situation. <g>
John
Mike,
After posting you a note, I thought I'd go back and check once again. I've
really pushed the limits on transparency from time to time and if this had been
a typical problem I think I would have encountered it somewhere along the line.
So here was my simple test to reconfirm that it does in fact work the way its
supposed to.
What I did was render a white ball as a single frame fli brought it into the
materials editor as an "opacity" map at 100, made diffuse white, everything
else is default, created a box in 3d build, took off the sides, which just left
the front face, applied the map and the mapping coordinates, put one spot on
it, rendered it through the camera viewport with a blue background and it was
perfectly clean. Its a really small file so if you want it, I'll send it
direct.
I just had to check… <g> I'm kinda suprised no else has responded, I would
think this is a fairly common practice.
The only thing I can think that might be giving you a problem is if your
fli/flc whatever isn't gamma corrected to begin with.
Hope this helps…
John
I appreciate the checking — actually, their are only three "problems" with
transparency, and they can all be worked around ("they're not bugs — they're
FEATURES!"). Your tests didn't use a object lofted with mapping coordinates,
so at least two of them wouldn't show.
1) The new "transparency" setting in the 3DS.SET file make it impossible for an
object to be completely transparent against anything other than a black
background. Leaving it to the default OFF position will work, though.
2) The Filter Maps has to be turned off for anything other than a black
background. Neither of these two problems will show unless you have something
other than a black background, and they won't show for a single face as in your
test, because the filter mapping works on the edges as the map is applied
"around" an object.
3) The killer. When you loft an object with coordinates, and apply the opacity
map to it (after rotating 90 degrees, of course) the "end" of the object will
not become transparent, no matter what you do. This shows even against a black
background (although it's more noticable when the background is not black).
The only workaround I've found to this is to select the very end of the object
and remove the face(s) — then everything is fine. I do believe this is a
"bug" and not a feature, but apparently it's not too critical or it would have
been corrected by now.
Hi Mike,
>> The new "transparency" setting… against anything other than a black
background… <<
If you're talking about the opacity map's background, I've always used black.
If you're talking about the background for the object with the opacity map on
it, I've gotten the results I posted.
I typically do use the "new transparency". One of its "features" is that it
creates alpha images when used with mapped lights on transparent objects, which
is nice for creating cookie cutter effects.
I will look into this further when I download spool.zip.
Thanks,
John
>>When you loft an object with coordinates, and apply the >>opacity map to it
the "end" of the object will not become >>transparent, no matter what you do
Mike. I'm getting caught up on messages and noticed this one from a few days
ago. I ran into the "end" problem long time ago but my poor brain can't
remember what I did to fix it. However, this seems to work today…
– put the animated opacity map flic in the Opacity Mask slot as
well as the Opacity Map slot
– in the Mask mapping parameters dialog, add a slight
V-Offset, such as 0.1 or 0.01
I have tried this in test renderings only, not in a project. Also, to me, it
looked like the moving edge was cleaner when using a mask.
JKJ
>> What I did was render a white ball…
John, try lofting a long twisty "shaft" in the lofter. Mapping coords
on. Length repeat 1. Perimeter repeat 1. Create an animated
opacity map that goes from all black to all white, over time. As
soon as the "beginning" of the shaft appears, so will a little of the
"end". It appears that texture filtering, smooths across the seam
from beginning to end ("wraps around").
See my note to Mike, where I left some suggestions. It's an odd problem that I
dealt with about a year ago. Rather than fighting for the "perfect" look, I
just hid the "glitch" as best I could and got on with the job.
– Dave
Thanks David,
I will check it out. I have done a few "handwriting" type animations
and that would be the time that I should have encountered the problem
but for whatever reason it wasn't a factor… probably because I
didn't cap the ends. I've come to realise this happens much more
frequently than I would have suspected by watching the myriad of
calls for help on things that just weren't a problem. So hence my
interest in these seemingly unusual situations.
I do like the "new" transparency feature very much. It works on a
object with projector lights and diffuse set high very convincingly.
It is in fact one of my most favorite features, so I hope it would be
continued in its present form. I would also like to see a "masks"
slot added to projector lights, as that would be a very powerful
combination indeed. I think of it as painting with projector lights
with full Alpha support. Its really marvelous.
John
John
>> I do like the "new" transparency feature very much.
I've had some trouble with "cookie cutter" opacity maps and "new"
transparency, so for most of my work I've elected to use "old"
style. I agree with all your thoughts, though.
– Dave
David,
>> I've had some trouble with "cookie cutter" opacity maps… <<
Right, well, the "new" transparency applies to "transparency" as a setting. I'm
using it straight with objects rather than with opacity maps. As I understand
it, it gives you increased saturation of colors so that when you throw a
projector light on a semi-opaque object the colors are richer.
So what I've been doing is creating flat planes and projecting the lights on
them almost fully transparent but with the specular color set at 255 white,
transparency at 100 SUB IN Shininess at 35 and Strength at 100. Then by
projecting a map from a spot on this using highlight place to pinpoint the
angle I can generate an image with alpha that just follows the outline of the
projected map, hence the cookie cutter reference.
Then edges aren't perfectly aliased but it works quite well.
John
>> I would also like to see a "masks" slot added to projector lights, as that
would be a very powerful combination indeed. I think of it as painting with
projector lights with full Alpha support. Its really marvelous. <<
I agree. I've been experimenting with new (for me) ways to present text,
and I really enjoy using projector lights casting text bitmaps. The text
flowing over objects is fun and interesting to watch, and usually quite
readable. Thanks for the detailed "how to" for the new transparency settings.
Paul S.
Paul,
Your welcome, I like to do a lot of multi-layering and I find this technique is
one of the most interesting ways to get really professional looking results. I
don't know of any other PC based package that has this capability, even though
its probably inadvertant. If you have already experimented with it then you
know that where the light is cast is where you get Alpha > 0. The beauty of
this is that you can use the spots falloff to create a nice soft edge. These
images can then be layered with different levels of transparency to create
montages that are really high end in appearance. The other way to achieve this
is with a paint package like QFX with which you can build alpha ramps, but its
alot easier and faster to do it with spots, except when I need to create a
mask. Sometimes I will run the sequence through VP with a matte, sometimes I'll
let QFX do it as it does come out a bit more saturated and detailed. Just
depends on where the focus is. You can use this in combination with Z-Depth to
create some really distinctive professional looking work.
If you come up with any refinements or complimentary techniques I'm always
interested.
John
John, I really like your application of projector lights. I haven't
experimented yet with this and I was wondering if you could possibly upload
some sort of small tutorial or example. How about something for Planet Studio?
It sounds cool, and I'd like to see what you're getting out of this.
DM
David,
Thanks for your interest, I'll see what I can do to accomodate your request.
John
David,
Per your request I've uploaded a small project file with a "transparency"
panel, a projector light and a simple material for projecting. The basics are
there and the short tutorial should get you headed in the right direction. I've
also included a sample image titled "Guys and Dolls" which makes extensive use
of this technique. The Curtain and the Pearls are both 3D 3DS rendered. I'll
let you figure out how it was all done. <g> The real secret you already have.
If there are any editors out there, who are interested in publishing this
technique as a topic, I can be reached email.
Thanks again for your interest,
John