Rendering - Object need NOT be calculated during certain intervals

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  04 April 2003
Question Rendering - Object need NOT be calculated during certain intervals

I've been attempting my first animations in Lightwave attempting to get a grip on how it all works.

I currently have a 90 second animation whose render times are very long (about 5 hours) without much going on. It seems this is due to a particular high poly object.

The problem is, for most of the animation, the object isn't even on camera. I don't want Lightwave to render/calculate the object during most of the animation (until it's moving on camera).

I re-read the manual last night to wrap my arms around my dilemna and discovered what I thought would be my savior. OBJECT DISOLVE. This morning, I jumped into my scene and created an OBJECT DISSOLVE envelope creating keyframes with 100% dissolve (and a -1 continuity to flatten the curves) where I didn't want the object rendered.

The problem is, even though the dissolve is sort of working (the manual says at 100% dissolve the object will not render at all), it it still calculating the object each and every frame (the renderer says, "optimizing object1" and that takes a while each frame). My render times, therefore, seem exactly the same.

My question is: if not OBJECT DISOLVE, is there a parameter (with an envelope option?) that I can assign an object which allows me to NOT calculate an object when I want, and calculate it when I need to (saaaay, when it's on camera)?

Thanks all,

Chan
 
  04 April 2003
Answer is "no" if you want an animated dissolve.
But once the object is dissolved you can interrupt rendering and then double check "unseen by camera" and "unseen by rays" in the object properties panel. Then it won't be calculated at all.

(you can also replace the object with a null for an optimum memory gain)
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  04 April 2003
Hey there, Facial Deluxe gave you a good solution for rendering up to a point in the anim. However one thing you can do if you don't want to stop the scene is to go to the render properties and switch off ray trace otpimisation.

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  04 April 2003
Just turn OFF this option (ray trace optimization) this option needed then u have really heavy objects with ray tracing reflection / refraction enabled ... Try some test render with this option and without - use this only if u really get some good render time saving.
Another thing - unless u use some transparent object with refraction u can reduce ray recursion limit to 4 .
Use adaptive sampling ON on camera panel and lower the default settings (0.1) to 0.06 - it's make bit better anti alias but without rerender frame 5 times. Note : this option working only if Motion Blur is OFF .
Hope this will reduce your render time
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  04 April 2003
I would render it as an image sequence, doing what Facial said and leaving this object "unseen" by camera and rays until you need it. Just render frame 0 to frame X (where the object is about to come onscreen) then render frame X to frame Y (where the object goes offscreen) then render the remainder. Composite sequences together in app of choice (even LW). Add salt to taste.

Brett
 
  04 April 2003
OK, just to make sure I have this correct (and I do appreciate the global help-- the community, as usual, is fantastic)

What we're basically saying here is that the switch to turn off or on rendering of an object is an absolute. So the only? way to do it correctly is to create separate rendering sequences. A set of frames with the relevant object(s) off (seen by camera) and a set of frames with the object(s) on (seen by camera) and then use a compositing tool (Premiere in my case, Combustion for the rich people, etc.) to splice them all together.

Do I have the correct idea or am I still not the sharpest knife in the drawer (A distinct possibility)?
 
  04 April 2003
Facial,

Exactly. I don't need an animated dissolve at all. I just need a method that turns an object on or off as I need it (This effect can be instant and not based on a curve).

Is this possible or am I relegated to my composite software?

Last edited by ChandlerL : 04 April 2003 at 11:48 PM.
 
  04 April 2003
I tried some advice, setting the object parameters to "Unseen by Camera", "Unseen by Rays," and Lightwave still INSISTS on optimizing the object.

grrrrrrr...

Anything else?

P.S. Is what I'm asking that unheard of? To not calculate or even consider an object that is off camera?
 
  04 April 2003
Turn off "extra raytrace optimization". This in fact makes for longer rendertimes with Subpatch- objects.
If the object is not deforming you can freeze it in Modeler before rendering, which will be much faster (ypu can turn extra raytrace optimization on then). I would also recoommend making a version of the scene without the object in it at all (for the parts where the object is not going to be seen). I have never had tha muc of a problem with LWs rendertimes, that I had to do this (and I have doen a lot of cinema- res stuff too).
Hope that helps.
CU
Elmar
 
  04 April 2003
What I would do is save out 2, or 3, versions of the scene

First one with the scene as is, rendering the frames the object is in shot

Second one, deleting the object, and rendering the frames the object isn't in shot.

Third one as above if the object is only in shot in the middle of the scene.

That way you'll only get the extra optimisztion time on objects that are necessary.
 
  04 April 2003
Oh, the other thing to try is making sure that on the object in question (although worth doing for all objects) the display subPatch and Render SubPatch levels are the same... This can drastically cut down render time, and prolly solve your problem...
 
  04 April 2003
Fantastic tips guys-- each one of them were a piece of an optimized puzzle.

Things are going much better now since following all the tips given. I had on many extraneous options I didn't need (such as Ray Trace Optimization) -- most were on due to Lightwave defaults.
 
  04 April 2003
Another way you could cut down on time is to make a copy of your object in Modeler. I'm assuming that it's a decently high poly object with sub-patch turned up for rendering. In Modeler, you can make a copy of the object, and instead of sub-patching it, sub-divide it (with the meta-form option) until it looks as smooth as you want. While this will give you an incredible poly count, it doesn't matter if you're done animating. Then, in Layout, go to your object properties and put display sub-patch and render sub-patch down to 0, and replace your object with your new one. It probably won't be possible to animate with ne new object since it's so heavy, but when it comes time to render, the computer doesn't have to sub-patch the object, and rendering should go faster.
 
  04 April 2003
The models I'm dealing with are spaceships-- so no sub-patching. I still copied down your tip for when I DO subpatch. You also mention something very interesting and that is turning down the display & render subpatch to 0. Again, I don't have sub-patched objects in my scene and left those settings at their default (which if memory serves is 4). I wonder if turning them down to 0 will give a speed boost. Is that what you're saying?
 
  04 April 2003
Quote: Originally posted by ChandlerL
The models I'm dealing with are spaceships-- so no sub-patching. I still copied down your tip for when I DO subpatch. You also mention something very interesting and that is turning down the display & render subpatch to 0. Again, I don't have sub-patched objects in my scene and left those settings at their default (which if memory serves is 4). I wonder if turning them down to 0 will give a speed boost. Is that what you're saying?

Another great way to speed renders up is to set up your scenes to render while you sleep.
 
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