View Full Version : Aliasing issues

Mr. Limpet
01-11-2007, 04:59 PM
This is kind of a bonehead problem but I need to try to come up with a solution.

I am not a full time Lightwaver. I do alot of work in After Effects and sometimes use Lightwave. I have had this problem since the rendering changed with all the PLD choices. I am always on such a hard deadline that I wind up having to live with render problems and then don't have the time to go back later and try to find a solution.

I have been seeing significant aliasing in finished material. The project I just finished had some boxy shapes with sharp hard edges. The aliasing on those edges was pretty bad. I am not inexperienced with video, I know about dealing with scan line and interlace issues. This is bigger than I used to see with the old renderer. I don't know if some user setting changed when I upgraded to that version of LW (was that 8.2?). Currently I have LW9.

Also notice that ray traced reflections are showing alot of aliasing. But maybe that's just a limit of using ray tracing in LW.

I have tried rendering to different codecs, changing field order (the output is broadcast), rendering to 60fps (no fields). I have tried different levels of rendering passes, adaptive sampling, softening filters. I have rendered as high as PLD 9 (for SD NTSC final product) and still see big aliasing problems.

I don't know if there is a definitive answer to this.

I am asking for any advice on what strategies I might take to reduce the problem. Is there anything I can do prior to the render stage? If I turn the render passes up more the render times are going to become unrealistic.

Thanks for any info, sorry for such a basic question.

01-11-2007, 06:51 PM
If you compare PLD-5 with Classic Enhanced Low (also 5 passes) you'll see that PLD not only looks worse, but also takes longer. The only time PLD saves you any time is when you use 3 passes or less, and it never looks as good, even at max settings. I don't think it's good for anything but previews. The Classic reconstruction filter is still the best and too.

Raytrace reflections does not directly require more anti-aliasing. If however you have a surface that becomes brighter than 100% white, for any reason, this can become impossible to anti-alias. This can happen if you've added refection and diffuse together on a surface, bringing it's total reflective property above 100%. Set your Image Viewr to 'FP' (floating point) and sample any bright areas.

If you have to use raytrace refection instead of reflection maps, make sure your ray recursion is as low as it can be, that will save you lots of rendertime. Shadow-mapped shadows instead of raytraced might help too.

Adaptive sampling saves time, but lowers quality.

Mr. Limpet
01-11-2007, 11:24 PM
thanks very much for your answer. I will do more testing next week. The current project is done and out the door, but I am taking the shot I had so much trouble with and rendering numerous times trying different settings to settle the issue.

I will give your suggestions a shot. Didn't know the reflections/diffuse issue and I will look at that. Will try the Classic rendering methods. I believe I used to use Enhance Medium for most stuff before PDL existed. Enhanced Medium wasn't perfect but seemed a good balance of quality vs. render time for the types of projects I do.

Not sure how to set the viewer to float except to select float from the general options menu under the "o" key.

Again, thanks very much!

01-12-2007, 02:11 AM
No problem! And if anything's not clear just ask :)
When PLD came out I did a lot of tests trying to find something useful in it... couldn't... find anything...
anyway Image Viewer FP is in your Render Options panel -

"The Classic reconstruction filter is still the best and fastest too."
(I hate typos)

01-12-2007, 05:04 AM
When you say you render to different codecs, please explain? Have you tried rendering out as a image sequence instead?


01-12-2007, 05:08 AM
If your images are getting too bright for AA, set Limit Dynamic Range in the Process panel. This will clip the high values so they will be AA-d properly.

01-12-2007, 07:31 AM
For boxy shapes like that you might try rendering with the "Gaussian" or even "Gausian (Soft)" reconstruction filter. This may increase render time over one of the classic methods, but it does tend to soften edges a little. You can then take the final into AE and hit it with a sharpen filter to bring a little crispness back to it.

Mr. Limpet
01-12-2007, 09:16 AM
When you say you render to different codecs, please explain? Have you tried rendering out as a image sequence instead?


Hi Mark,

Some background. Most of my time I am a video editor. Most of the projects I edit I also create graphics for, mostly Photoshop, Illustrator and After Effects but some Lightwave. I am used to working with video clips within those types of apps so I have always rendered Lightwave directly to a video file, usually Quicktime using whatever codec is appropriate for the destination. So if the Lightwave animation is being used directly in Avid, I render to one of the Avid codecs with lower field interlace @ 29.97fps. If it is for direct use in Final Cut Pro I will render to the appopriate codec for whatever IO hardware is being used. If it is being composited in AE I render with no compression or with animation compressor. If I have time I render at 60fps progressive (no fields).

I would be interested in knowing the opinions of Lightwavers as to whether rendering to an image sequence improves the quality of the image.

I have always rendered final animations out of AE directly to the appropriate codec for the editing app. I have found some graphic artists like to render finals out to Animation codec but that takes alot more time to import into the editing app and I can't see the difference on reference monitors or scopes. So I have always considered Animation compressor final output superiority a kind of urban myth unless you don't know what the destination app is and need a generic file that can be imported into any editing app. Would be happy to be convinced otherwise however so I will try rendering out to a targa (or whatever you might recommend) sequence and have a look.

thanks for that tip, will try that.

among the many settings I tinkered with was trying all three settings of Gaussian. Straight Gaussina looked too soft to me and I could still see the jaggies under the blurring. But that was with PLD. I will try that in Classic and look for any difference. I also tried Mitchell but really couldn't see any difference compared to Gaussian on the difficult shot. I will try your tip of adding a little sharpening in AE to the shot rendered with Gaussian.

Thanks alot to everyone.

01-12-2007, 10:26 AM

It sounds as though you and I have very similar workflows and uses for LW (although I do some hobby stuff as well).

Anyway, I used to render from LW the exact same way as you are describing and have since changed my ways.

For very long renders, which I had a project last year that required it, rendering out as image sequences saved my life. They had little changes in the video sequences I was mapping on to objects, and luckily since I had rendered out image sequences, all I had to do was render the frames that changed, a big big time saver. This is even more crucial since I render out at 60fps progressive as well for NTSC video use.

I always render Targa sequences, although that may change when I get the soon to be announce AE 8. I will probably switch to OpenEXR since it has lots of other data from LW that AE can use. I always process LW renderings through After Effects whether it needs it or not, but since it is 60fps and image sequences, it usually needs it.

Here is a screen shot showing the renders settings I am using for my current project. This will be output to BetaSP from Final Cut Pro using an AJA IoLA interface; component video.


Mr. Limpet
01-12-2007, 02:26 PM
Im am interested in OpenEXR as well but had not thought of it as an intermediate for 3d elements. I thought AE 7 could handle HDR float images. Don't know one way or another whether it handles OpenEXR. I wonder if rendering to such HDR type images would elimate aliasing on very bright parts of the image.

Took a look at your settings. Pretty much the same as what has been recommended with Classic Enhanced Med. In testing I tried all three Gaussian filters but like "sharp" best.

I hadn't thought of making revisions directly to the targa sequence since as an editor I have always been making the graphics for myself and just rendered out revised sections as Quicktimes and cutting them into the original animation with the edit system. Of course that results in alot of outdated media piling up with multiple revisions and I can see the image sequence route would help manage that. I am going to give that a shot.

Thanks very much for your help!

01-12-2007, 02:44 PM
Cool Gary,

Hope it works out. I am still stuck in AE 5.5 standard land, so the upgrade (company) to AE 8 Pro is going to really be nice.


01-12-2007, 04:01 PM
AE7 can handle OpenEXR images... but only reads the contained RGBA channels (no multi-buffer exports in a single file).
I sincerely hope this will change with AE8.


01-13-2007, 01:13 AM
Lots of good reasons to render to frames!
1. Crashes or power outages can ruin a quicktime or avi file, forcing you to start the render from the beginning again.
2. When rendering to frames, you can stop and restart the render any time you want.
3. If one or a series of your frames renders wrong, you can go back and re-render that frame without having to do any editing.
4. You can save high bit-depth images
5. You can inspect frames or parts of your animation before it's completely rendered.

01-13-2007, 03:15 AM
Plus if you render out in a lossless format (tiff, targa etc) then you'll see which discrencies are being added by Lightwave's renderer. I'd be loath to save anything out in an animation format (or still image format) with codecs applied as there will be some loss in quality from the start. Sequences is the way to go :)

Mr. Limpet
01-15-2007, 01:28 PM
Thanks for everyone's help. I have just one more question. How do you handle fields when rendering to an image sequence. Do you render 60fps progressive and convert later or do you render directly to a 29.97 image sequence with interlace?

Thanks for all the info!

01-15-2007, 10:32 PM
Thanks for everyone's help. I have just one more question. How do you handle fields when rendering to an image sequence. Do you render 60fps progressive and convert later or do you render directly to a 29.97 image sequence with interlace?

Thanks for all the info!
I've never used fields, but if you render them into the frames you can't do things like blurs or paint fixes, so I'd probably convert later -