View Full Version : Render artifacts.

05-14-2006, 08:27 PM

I'm having a render issue. Some of the polygons are rendering transparent. See attached Jpgs. It seems to be a camera "angle" issue. If I move the camera, certain transparent polys, become opaque, then different ones become transparent. Bahg! Checked and made sure all the normals where in the right direction.

Ideas anyone?

Mr Papabeis

05-14-2006, 10:33 PM
This is just something to try. I'm not sure if it will work. Make your surfaces double-sided and see if that works. Aside of that, I can't think of anything at the moment.

05-14-2006, 11:00 PM
Hey, Mr Papabeis,

Yep, you likely have some polys flipped. You could make your polys double-sided, as cobaltman suggested, but that'll add to the rendering time. You may just have small group of polys that are facing the wrong direction. To fix this, load your object in Modeler and under the Detail tab (in 8.5), click Align. This will make all your polys face the same direction. Hope that helps.:thumbsup:

Whoops, sorry - I missed where you said the normals were already facing the right direction. Double-sided might work...

05-16-2006, 10:05 AM
Guys this is maddening.

I did this test and I get the same transparent polys. And to top it off there seems to be no pattern. If I move the fish outside of the bowl they render fine. If I leave them in the bowl and turn off ray traced reflections, it renders fine. I set up an identical second camera, pull out a bit and now its ray trace shadows that causes the error. What the? The witch (see previous post) does it with no raytracing at all. The double sided thing doesn't work. Do i need to adjust spline bias on my models or sumpin?

I'm try to get some work done.

Please help someone.....

Mac G5, dual 1.8, GeForce FX 5200, 2GB ram

05-16-2006, 11:08 AM
Are there any errors in your geometry? What I mean is, are there any overlapping bits? In this case it doesn't look as if there would be but like you I've had this maddening problem.... clutching at straws really....

05-16-2006, 11:10 AM
I have not been in Lightwave very long and am still learning, but I try to help as much as possible. There are actually two ways to "double-side". Maybe trying to use the other method will help. Here are the 2 ways of doing it:

1. Click the "Double Sided" option in Surface Editor.

2. In Modeler, go to the Detail tab an check the More list under Polygons. One of the options say Double Sided. This is a little different than the first option in that it actually makes a double of the object and flips the polygons, thus making a REAL double-sided object. The first option only makes an illusion, if I'm correct.

If you haven't tried the second method, see if it works. Other than that, I can't think of anything else. Dodgy or SlineGod might know what to do.

05-16-2006, 12:02 PM
just an idea.. but is it possible that there are 2 sets of models?? I have seen things like this in the past were...just by accident, you copied and pasted the model on top of one another...check your point and poly count....

again... just an idea..

will keep looking


05-16-2006, 02:19 PM
I have seen that problem in my renders too. With me it was only in the shadow though... Luckily for me I was only rendering stills so I touched-up the still in photoshop.
Never knew what caused the problem though...

05-16-2006, 03:12 PM
I`ve had this promlem too, I got around it by selecting the affected polygon and polygons surroung it and subdividing them, Hth

05-17-2006, 03:44 PM
Things that have not worked so far;

1) Double sided polys, both ways.No dice. Actually made it worse.

2) Checked to see if I have 2 copies of the model.Didn't.

3) Reset my menues/plugins. Nope.

4) Tried various render schemes. Nada. See attachment for global illumination.

5) Put your advice in this space for only $19.95. Kidding.

Thank you Sarford and esper8 for your replies. At least I know its not just me.

Mr. Papabeis

kiwi dave
05-18-2006, 05:12 AM
Could you post a wireframe of the head so I can have a look at the polys around the problem areas.

I'm thinking its a poly-flow issue.


05-18-2006, 05:58 AM
That last image seems to have realtively large quad polygons across the top of the head...

I have had similar issues where there were non planar polygons, (particularly when importing from poser, or applying morphs). These were simple fixed by triipling.


05-23-2006, 08:23 PM
starbase1 had the right answer. Changed the Quads to Tris. Worked like a charm.


05-24-2006, 11:40 AM
My work here is done...


05-24-2006, 01:11 PM
just so we all might learn from this:

were the models subpatched or frozen? maybe this was all caused by nonplanars after a freeze.

my original guess was going to be that Satan :devil: was behind this, since it was a rendering of a wicked witch. Glad to see that good triumphs over evil yet again....

05-24-2006, 11:00 PM
Actually this was a Daz/Poser model. Victoria 3 with a "witch" morph. The morph slider, appropriately called "witch" at 100%. Not frozen. Just bent the **** outta the quads.


05-27-2006, 02:06 AM
Other things to note;
Turning on double-sided can give you self-shadowing polygons, showing up as black outlined polys when raytrace shadows are on, like the last posted image.

Non-planar polygons that render ok can appear to explode when rendered behind a refractive surface, like the fishbowl.