View Full Version : SkyTracer Render Problem

11-30-2003, 09:56 AM
I'm using a PowerMac G4, 1G ram, Lightwave 7.5.

I have a scene using a sky generated by SkyTracer. When I render a single frame of the 660 frame anim, the sky shows up as expected. When I render and save a single frame of the anim, the sky shows up as expected. However, when I render and save more than one frame (2-660 frames) as a Quicktime movie, the sky is completely empty...nothing is rendered. I'm sure it's something simple, but I've been through the manuals and this board, but can't figure out why. Any help out there?

11-30-2003, 11:05 AM
Additional info to my previous post:

It's not just a problem with SkyTracer. No matter what I choose as a backdrop it does not render.

11-30-2003, 11:17 AM
Are you network rendering when rendering out a sequence? If so, perhaps the network machines are not seeing the object and images for the sky. If this is happening on a single machine while rendering the sequence, then I'm not sure what's going on.

11-30-2003, 12:26 PM
Does the backdrop come out white?

Whatever you're using to view the animtaion may be pre-multipying the Alpha channel. Backdrops generally don't affect the alpha channel, so it gets cut out.

You can either change the Quicktime settings from Millions+ to Millions, or better yet, render to an image sequence.

Quicktime mov files have several disadvantages:

1) LW doesn't handle Quicktime very well, stability issues

2) Frame rate conflicts when using a QT as a texture, and between Layout's frame rate and QT's

3) If you render all day to a QT, and LW crashes or there's a power failure, you'll have to start all over again. If you've been rendering to a sequence you can just pick up where you left off.

4) You can't view frames until the entire QT has been rendered

5) Much harder to clean up an individual frame

There's even more than that I just can't remember right now -

11-30-2003, 12:34 PM
Hey guys. Thanks for the quick replies...

Not network rendering. Just the Mac.

As far as the backdrop - it doesn't come out white or any other color. It's completely not there at all. Vapor. Vanished. If I put a matte background into another video channel in Final Cut, it shows up behind the object I'm rendering. I guess the easiest thing to say is that LW is rendering ONLY the objects in the scene and nothing else.

If I render to a sequence, is there an easy way to combine those individual frames into a Quicktime movie that you know of?

11-30-2003, 12:42 PM
Then it is being pre-multiplied. A lot of compositing apps do this automatically. I've never used Final Cut but there must be a way to tell it to not pre-multiply, look for something like "interpret footage", and there's definitely a way to bring in image sequences.

I use QT Pro to open image sequences if I just want to view the animation, then you can also export a .mov if you want.

11-30-2003, 01:17 PM
Thank you, guys. Your help is greatly appreciated. As a LW newbie I plan on spending a lot of time here...so hopefully one day I'll have something to contribute back to the discussions.

11-30-2003, 01:23 PM
this place is awesome. I've been hooked for years, it's like a drug that teaches you LW :D

11-30-2003, 04:58 PM
FCP automatically removes anything in the alpha channel if there is one, to stop that, choose the item properties, and where it says alpha - either black, or white, change it to none/ignore. That will allow your backgrounds to show. AE asks you on import what to do with the alpha channel, and quicktime automatically leaves the alpha channel alone. Are you not seeing the background when you open it in quicktime?

Image sequences do seem like the best way to go, unless you're just rendering quick test animations. If you use OSX though and you render images with alpha channel and view them through the preview animation just remeber that it removes the alpha channel automatically, and there doesn't seem like there's a way to disable that feature.

It seems weird that LW has problems with quicktime movies, both rendering to them and using them as textures or backgrounds. I mean, quicktime it a ginormous (made up word) standard, and i don't know of any other program out there, mac anyway, that can't handle quicktime correctly. The stupidest thing i noticed lately is that when i wanted to render to quicktime and set the frame rate in the quicktim options panel to 15fps, it still rendered to 30fps. Pathetic.

11-30-2003, 06:22 PM
Dang. You guys are good.

11-30-2003, 08:35 PM
please, my modesty :)