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Major Bug in Motion 3.02

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Collin Alexander
Major Bug in Motion 3.02
on Jan 11, 2008 at 5:53:42 am

I'm convinced it's not me. Motion has a major defect. Paint and Particle emitters do not exist correctly in the 3D environment. They will appear either in front of or behind other objects depending on layer order, not depending on where they are in 3D space.

Here are 2 test clips. A video with a red blob. Neither the video nor the blob move in either clip, only the camera moves. The difference is the layer order. If the video is on the top layer, it will appear to be in front. If the video is on the bottom layer, it will appear to be behind.

If someone can make particle emitters and/or paint exist correctly in 3 dimensions in Motion, there would be a paying job in it for you. Leave an email address. Thank you all for your help so far, but I sincerely believe this is a major bug.






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Jim Johnson
Re: Major Bug in Motion 3.02
on Jan 11, 2008 at 4:47:08 pm

Howdy,

This isn't a bug: it's a reality of 3D compositing. In certain situations, a compositor has to precomp parts of a scene, which can prevent them from intersecting or being depth-sorted. In After Effects, people refer to it as "police-taping". In Motion, this is referred to as "rasterizing". Rasterized 3D objects (3D groups, 3D particles, paint, replicators and text) will be composited into the scene in layer order. If you look up "rasterize" in the Motion manual (especially the 3D supplemental in the Help menu), you'll get some examples and explanation of what can force rasterizing.

With regard to particles, they can do 3D in two modes: Local and Global. By default, 3D particles are set to 'Local 3D', which means that they don't intersect with anything but themselves. This makes a huge difference in performance, because Motion has to do fewer calculations. If you switch the particles to 'Global 3D', then they will intersect with everything in the scene, so they can appear in-front-of or behind other objects, but will run a lot slower. Even 'Global 3D' particles can get rasterized (and layer-ordered), if you do something to force it, such as applying a filter to the particles.

3D replicators are always in 'Global 3D' mode. 3D paint strokes, however, are always in 'Local 3D'. If they did Global, I can only imagine how long the render times would be.



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Collin Alexander
Re: Major Bug in Motion 3.02
on Jan 12, 2008 at 3:44:36 am

Nope, didn't work. I switched from "local 3D" to "global 3D" and the particle emitter is still visible through the video in front of it.

It's a bug.




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Jim Johnson
Re: Major Bug in Motion 3.02
on Jan 12, 2008 at 6:02:24 am

Howdy,

This is why I asked you to post a screenshot or description of the Layers list. Do you have any filters applied to the particles? Is their blend mode set to anything other than Normal?



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Collin Alexander
Re: Major Bug in Motion 3.02
on Jan 12, 2008 at 5:22:10 pm

Here are examples using a blob of paint. The emitter has the same behavior. If the emitter is 2D, it will behave correctly in the 3D environment. If the emitter is 3D, it will show/disappear according to layer order.

Here are two examples, the only difference is the layer order. One has the paint blob above the video, the other has the paint blob below the video, and neither one of them behave correctly.

Blend modes are all normal.






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Jim Johnson
Re: Major Bug in Motion 3.02
on Jan 12, 2008 at 8:48:11 pm

Howdy,

This is why I keep asking for a screenshot of the Layers list. You have an image object (the video) and an emitter in your project. Are they in the the same group? What type of group is it? Are there any filters applied to the emitter? If the emitter is a preset, which one is it?

It's possible that you're encountering a bug, but since other people (including myself) aren't having a problem with this, it's likely something that is specific to your project. The more detail you can provide, the more likely we can figure out what's causing the forced layer-ordering.



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Collin Alexander
Re: Major Bug in Motion 3.02
on Jan 12, 2008 at 10:58:02 pm

I'll get you that screenshot when I'm able.

I've tried them in the same group, I've tried them in different groups. I've tried re-ordering the groups. I've tried re-ordering the objects within one group.

I've tried stock emitters such as "data flow" and others. It doesn't matter, behavior is the same.

I'm sorry to be harsh, but I simply don't believe you when you say you don't encounter this problem. I would be ecstatically happy to be proven wrong.

The bug is as follows:

2D particle emitters behave correctly in the 3D environment. That is, when they are behind an object, they disappear, when they are in front of an object, they show.

3D particle emitters behave incorrectly in the 3D environment. Whether or not they show/disappear with other objects is dependent on layer order, and has nothing to do with position in 3D space.

It does not matter if 3D render is set to "local" or "global". Bug is the same.

With paint, the problem is similar. Certain brush types behave correctly, other brush types always follow layer order.

It seems Motion is in a transition phase toward becoming a true 3D environment.



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Jim Johnson
Re: Major Bug in Motion 3.02
on Jan 13, 2008 at 5:45:41 am

Howdy,

I made a project that has a Checkerboard generator and two simple 3D particle emitters in sequence (one starts after the other ends). Both emitters are located in front of the checkerboard (from the camera's starting POV). The camera then does two orbits around the checkerboard.

On the first pass, you see the emitter set to Local 3D, which appears to always be on top (in front of) the checkerboard, because it's on top of it in the Layers list.

On the second pass, the second emitter is set to Global 3D, so it's checking for intersections and depth-sorting with the whole world (if possible). As the camera moves around the checkerboard, the checkerboard occludes the emitter. Now, if I were to apply a filter to the emitter, that would force it to rasterize (precomp) and then it wouldn't be depth-sorted, anymore.

A movie of this project can be found here and the project file can be found here.

Hope this helps.



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Eric Meek
Re: Major Bug in Motion 3.02
on Jan 14, 2008 at 7:26:59 pm

not to be harsh but i think YOUR LYING. trying to bash apple. You can provide us a screen capture of your movie but you can t give us a screen shot of teh layers tab? This tells me the movie is maybe from not your copy of motion. I have never had this problem and nether has anyone else, how can you say its a bug and not you when your the only one experiencing it?

Why are you so affraid to admit it may be you. NO ONE and i mean NO ONE has had this problem. you need to re think your project because it sounds like its you not motion.


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Collin Alexander
Re: Major Bug in Motion 3.02
on Jan 15, 2008 at 12:14:12 am

Actually, Gary Allen has confirmed the same issue:

http://forums.creativecow.net/readpost/8/970292

The demo and comments posted by Jim Johnson above is encouraging, but he has used a still picture, not a video. Perhaps the rendering is correct around a still, and not a video. I'll have to try that.

In any case, Jim Johnson confirms the problem, not as "a bug", but as a reality of 3D compositing. Fair enough. It's a bug to me.

My studio computer is not wired to the internet, so it's a little cumbersome to upload screenshots. I thought I provided the information requested. I'll try out some more iterations of "3d local" "3d global", still pictures vs videos, etc. and at least be able to give an even more detailed report on when 3D works and when it doesn't.

And I'll take screenshots of my layers tabs.





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Jim Johnson
Re: Major Bug in Motion 3.02
on Jan 15, 2008 at 3:30:31 am

Howdy Collin,

Here's an example of a 3D emitter sandwiched between two video clips, first in Local 3D and then set to Global 3D:



As I mentioned before, there can be certain conditions in a project that will force an emitter


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Collin Alexander
Re: Major Bug in Motion 3.02
on Jan 15, 2008 at 4:17:09 am

Thank you very much sir. OK. I'm not crazy, it's not me. It's not a checkbox. There are situations where the compositing is based on layer order, and not on position in 3D space.

I'll just use a 2D "data flow" and have the particles always face camera. It won't be as cool as 3D, but it will be OK.



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