Video shader problem
jrm21
Posts: 140
Trying to do a simple effect and running into a problem. I'm sure there is some easy solution I am overlooking.
Have a scene with a simple plane object. For the plane's shader I am using only a single texture channel. In that channel is a video (.mov file). I output the video at 24fps to match my Carrara animation output settings.
Everything starts out fine. Several seconds into the animation, however, the plane "disappears" for frame or two. It's there for several frames, gone for one, back for a few, gone for two, back again, etc. This goes on for a few seconds and then the plane disappears entirely for the final few seconds of the animation.
When the plane disappears, you can see the background behind it (i.e. it is no longer visible, as opposed to not being lit).
The disappearing only appears in the render. In the assembly room, the plane object is there the whole time.
There are NO keyframes on the plane in the animation timeline. (Visibility is "on" for the entire animation).
Any ideas what might be going on?
C8.5/Mac
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Comments
I just stumbled across the answer to my own question.
There was another object in the scene that had a keyframe for movement. This object did not interact or move near/across/through the plane. Somehow, the other object's movement was affecting the plane with the video shader.
I deleted the movement keyframe from the other object. The plane now renders visible throughout the entire animation (at least in test renders. The full render is happening right now).
Very strange. Any ideas what could be causing this?
Isn't be the object which would reflect the light on the plane?
And your camera is fixed ?
Ooops. Sorry. Just woke up!
Glad you've found the solution!
My scene is set up like this:
Ambient lighting at 5%
Background is a starfield jpeg image
Objects:
Plane (with video as texture)
Plane Light: spotlight shining on plane to illuminate it
Sun object (sphere)
Sun Light: light with effects (this is a bulb, not a "sunlight" light)
Earth (object)
Earth Light: spotlight shining on earth
Both the sun, sun light and earth objects are from the "solar system" defaults that come with Carrara (or are/were available free from Daz). Earth is in a group with its light and the sun is in a group with its light.
Camera moves through the animation.
The plane and its light do not move for the entire animation, and there are no keyframes in their timelines.
The earth and sun originally moved positions during the animation. Again, they never came between camera and plane.
Thinking the problem was with some sort of light interference, I changed the lighting parameters. All three lights were set to illuminate only their own objects. Earth light lit the earth, sun light lit the sun, etc. That did not fix the problem.
When I turned off visibility for both the earth and sun groups, the problem went away. When I only turned off one or the other, the problem remained.
What I then decided to do is eliminate movement of the "earth" group. It spins in place, but does not change position. For some reason, this eliminated the problem and the plane stays visible through the entire render.
I don't understand it, but that's what happened. Would love to know what was going on.
I thinks that the problem could come from the shader of your plane, is there a reflection?
When you use a footage like this, it is preferable to put all on “none”, except the channel color, naturally…
That was the first thing I did. Every shader channel is set to "none" except the color channel. Color channel is set to texture and has only the movie placed there. Movie length exceed the Carrara animation, so no looping, scaling or other effects are applied.
I don't understand, why do you illuminate your plane ?
Without a light shining on the plane, it appears black. You cannot see the video (color channel).
I sometimes used this method, but I don't remember to have had to light planes… When my PC finish a render, I'll check it.
Can't offer any help about the disappearing plane, but a good way to get your video to display on you object without having to light it, is to copy the map/movie to the glow channel. This isn't a one size fits all solution, but I find it extremely helpful in most situations.
Thanks for that. This (for my current situation) is the better way to "light" the video panel.
You are right, I have just checked.
The trick of EP is to be tested too.
I still thought of your starting problem, but I do not see an answer…
As for the other thing, perhaps there was some sort of sharing of shaders going on that was repaired when the keyframe was deleted? not sure. Sometimes I'll make a change for a test or something, and accidentally do it somewhere along the timeline, so the change gets keyed in, making all manner of issues. It's cool though, that we can just go back and find stuff in the timeline and move or delete it. Carrara just seems (to me) so easy in this regard.
Thanks all for the help.
Regarding the original problem, I am guessing it is one of two things. First, as Dartanbeck suggested, it may have been a sharing of shaders or something I did in the timeline. I would lean towards the sharing problem for a few reasons.
The other option - and this is what I think is more likely - is that there was a "perfect storm" of events. Everything was in the exact right place to cause this anomaly. Call it a bug, call it a freak calculation in the render engine, I don't know. Had I been in the frame of mind to troubleshoot this more, I could have tried to track down what caused it. Originally, I simply thought I was doing something wrong since I had never tried a movie in the color channel. I was in too much of a rush to fix it and stopped looking once I found a solution.
Since "fixing" the issue I have made several other changes to the scene and the problem has not come back. That (for now) is good enough for me. :)
After I finally got Howler, I made not only animated color maps, but for Highlight and Bump channels as well! ;)
We could also go for blinking lights on a console, using color and glow channels with .mov, sequenced images, avi. It's amazing - the thought of what can be done. I found it really neat to see the specular highlights change with the animation in the resulting render. The animated bump was pushing those areas out more, so the effect was further enhanced by that... It was all just an experiment, to see if I could do that if I needed to perform such a task later on, so I never did get really heavy into making it just right. The evidence that it truly works very well was enough for me. And being Carrara, the process is so much the same as I would expect it to be, there's no need for finishing the experiment just to lock the technique into my brain. It's just there already, since the shader system makes so much sense. I just love it!
I was using avi, much like you're using mov. I have a feeling that, if we want to do a lot of this in the same scene, it may be more advantageous to use image sequence animations instead. There were times during my tests that it seemed like i had to fight to keep the looping animations on the right frame, or animating at all, since I ended up with many of them in the same scene. I added these things to the hair and all items of clothing. Pretty impressive to me that it kept all of that straight at all... and sometimes it didn't. It's just a feeling... I just think that images sequences will ultimately be easier to track, when there a lot of it going on at the same time. But that's just a personal hunch - and the method I will be using when I need it.