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The Watcher
07-20-2005, 10:27 AM
I've run into a problem and for the life of me I can't see what I'm doing wrong here. The best summary is probably to show what happens - the two images here show a view out through a window, in the background a nebula and starfield should be visible. The image on the left has the window in place, as you can see all that is visible is the nebula. The image on the right was rendered after removing the window and now the stars are visible. No other changes were made to the scene. (click the images for larger versions)
http://fleet.starforge.co.uk/images/window_in_thumb.jpg (http://fleet.starforge.co.uk/images/window_in.jpg) http://fleet.starforge.co.uk/images/window_out_thumb.jpg (http://fleet.starforge.co.uk/images/window_out.jpg)

The stars and nebula are objects, not pre-rendered background, created using the techniques described in the AP3D BetterSpace tutorials (http://www.ap3d.com/betterspace/betterspace-tut-00.htm). The window is one layer in the room object, all the polys that form it have the Window surface and the settings for that surface are:

Color: 200 200 200
Luminosity: 0.0 %
Diffuse 100%
Specularity: 42%
Glossiness: 58.5%
Reflection: 9%
Transparency: 94%
Refraction Index: 1%
Bump: 0%
No smoothing, Advanced, Environemnt and Shaders tabs are all defaults.
(I should note that the problem persists even if reflection is set to 0 and transparency is set to 100)

I have enabled Ray Trace Shadows, Ray Trace Transparency, Ray Trace Reflection and Ray Trace Refraction in the Render Options. I have also tried increasing the ambient light to 100% to see if anything is being drawn very dimly but it is not - those starts simply aren't being drawn through the transparent object. I'm probably missing something obvious here, but I've searched and come up blank (of course, this could just be because I'm not sure what to search for).

Oh, and it's Lightwave 8.3 on Win2K.

Can anyone point me in the right direction here?

Lightwolf
07-20-2005, 11:56 AM
Single point polygons can not be raytraced (they have no "physical" dimension and thus a ray can't intersect them).
Since you need raytracing for the volumetrics though you should think about rendering in layers instead.

Cheers,
Mike

The Watcher
07-20-2005, 12:02 PM
Okay, thanks very much!

MonroePoteet
07-20-2005, 05:13 PM
If the windows are flat and fill the frames, you might just turn off ray-traced refraction, and maybe ray-traced transparency. Assuming what Lightwolf says about single-point polys having trouble ray-tracing (makes sense to me), that would be the cause of the windows "occluding" the stars, since the refraction raytracing would miss them.

mTp

Lightwolf
07-21-2005, 02:45 AM
If the windows are flat and fill the frames, you might just turn off ray-traced refraction, and maybe ray-traced transparency. Assuming what Lightwolf says about single-point polys having trouble ray-tracing (makes sense to me), that would be the cause of the windows "occluding" the stars, since the refraction raytracing would miss them.

You would need both turned off. However, if the nebula is a volumetric it won't render behind the glass then...
In that case it might help to just render the nebula, map it onto a poly and render the whole scene with raytracing transparencies and refraction off.

Cheers,
Mike

mgrusin
07-21-2005, 10:47 AM
You might look into Hyperstars (http://www.ficatech.com/plugins.htm) or Starpro (http://www.maasdigital.com/starpro/), especially if you're planning on animating your scene.

-MG.