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Pryzm
08-02-2014, 04:18 PM
really strange issue going on just curious if anyone has run into it.

I have an object that is made up of a stack of single face polygons (separated by about 60mm). It's a cloud object similar to this tutorial (http://iaian7.com/lightwave/FakingVolumetricClouds)

VPR will render them just fine, but F9 won't render them at all. As I troubleshoot the issue, I found that if I rotate the clouds 180 (about 173) it will then render with F9 but not in VPR. I wish I could attach something but can't until the project is over... :(

Has anyone run into this?

thanks

bruce

spherical
08-02-2014, 04:44 PM
In which direction are the poly normals facing and which render method matches that direction? IOW, are the polys facing toward the camera and VPR renders them or does F9 render them? That the rotation angle to make them appear is so specific is odd. Perhaps related to Ray Recursion Limit?

Pryzm
08-02-2014, 05:36 PM
Normals towards the camera and F9 doesn't render, but VPR does. I tried different RRL's with VPR, and nothing changes. The only thing that (at this point) gets them to render is to flip them over...but playing with it a little more, I did realize why it changes at 173. The object is large enough that at that angle it rotates down in front of the camera (so the camera sees the backside (normals away) of the cloud object).

So it appears that if the normals are towards the camera F9 won't render, but VPR does and vice versa...

Thanks!

bruce

spherical
08-02-2014, 07:47 PM
The technique depends upon backlighting the cloud planes and the use of translucency. If the normals are facing the camera, they essentially disappear to the light that is used to illuminate them.

Pryzm
08-02-2014, 07:52 PM
The technique depends upon backlighting the cloud planes and the use of translucency. If the normals are facing the camera, they essentially disappear to the light that is used to illuminate them.

and that does makes sense, but what doesn't make sense is the difference between VPR and F9 render. I thought they were supposed to match...

thanks,

bruce

spherical
08-02-2014, 10:10 PM
VPR is a great approximation. It's a previwer. Doesn't render equally in all circumstances. They're working on it and it has improved over the first version.

I just loaded up the clouds.low and clouds.scn to check out what is what and, even though the cloud plane normals in Modeler are facing forward, the object in Layout is rotated to have the normals facing away from the camera and toward the lights. F9 returns a full set of clouds. VPR returns a partially deep set, but it does render them. Lowering the RRL to 4 makes the F9 depth match the VPR.

Pryzm
08-02-2014, 10:27 PM
VPR is a great approximation. It's a previwer. Doesn't render equally in all circumstances. They're working on it and it has improved over the first version.

I just loaded up the clouds.low and clouds.scn to check out what is what and, even though the cloud plane normals in Modeler are facing forward, the object in Layout is rotated to have the normals facing away from the camera and toward the lights. F9 returns a full set of clouds. VPR returns a partially deep set, but it does render them. Lowering the RRL to 4 makes the F9 depth match the VPR.

Yeah, I've been using Lightwave since v5 (but I'm still learning new things all the time) and it has made leaps and bounds over what it was when it started out. :) I usually take VPR's render with a grain of salt, but it usually gets pretty close. It's just weird that it doesn't render an object out at all (or the opposite with F9).

I did try to set the RRL to a number of different settings (1, 4, 8, 20, 50) to see if that made any difference, but no go.

Thanks for taking time to help me out on this, I appreciate it. It really seems an odd (but probably explainable) situation. It's not a show stopper if I don't figure it out because I've figured out a work around, but it would be nice to know if I've found a bug, or if I found something else new to learn. ;)

bruce

spherical
08-03-2014, 12:15 AM
Well, that I get a render of those planes in VPR says that nothing is broken. I don't have your object/scene to look at in order to learn why you aren't getting anything. However, trust that the F9 render is good and go with that, no matter what VPR may be doing at the time.

Pryzm
08-03-2014, 01:00 AM
will do, thanks again for your help. I appreciate you taking the time to help me out.

bruce