AccuRender nXt

advanced rendering for AutoCAD

i spotted an unrealistic black part on the side of the glassplate in this image and when i right-click the rendering window to show the alpha channels this is the result. Since i don't know much about alpha channels i wonder what's happening here.

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Normally when this happens it means some light paths are finding there way to the background via transmission only.

 

There is a global switch you can try.  It's on the Advanced Lighting tab and it's called No Transparent Object Alpha.  It will prevent you from doing alpha compositing through windows so it may not work for you.  (I need to add a local switch here-- either material or object prop.)  Let me know how it goes.

"alpha compositing through windows"? Don't know what that means. Anyway, checking the switch doesn't change a lot. Only the alpha channel is no longer transparent, part of the face stays black as night. Changing te view angle gives te same result. You can view the final image in my albums as "livingroom2" I cheated by using the alpha channel to "correct" this in PS

Ah, that makes some more sense.  Turning up the refractive bounces may help (try 16?).  You've got some total internal reflection going on.

 

You shouldn't get any alpha for this in the very latest build so the cheat won't work anymore (> 271, I think).

 

*****

 

By alpha compositing through windows I mean the ability to see a color background (like a photo) behind a window with glass in it.  By default, nXt for AutoCAD is set up to provide alpha channel for this.  You lose that ability when you check the switch.

 

Turning up the refractive bounces doesn't change anything but i saw some strange behaviour in the drawing. I'll check earlier backups to see if the drawing file could be corrupted.

Still very likely to be total internal reflection.  The edges of tables are notorious for this.  If it's what I think it is, it's working like a fiber-optic cable where the light can't escape.  If you can't manage to get it out of there by adding extra bounces, then post-processing may be the only option.

 

It can, of course, be some other problem.

I have to stick with post-processing. The problem remains. Thanks anyway Roy.
Have you tried rounding the edge of the glass top, or using another material like plastic on the edge?
Yep. Actually the glass solid is filleted. I'm affraid that changing the material won't satisfy me. I also have to explode the solid to be able to do that,no?

Was any solution found for this apart from post processing, for those of us not Gurus in PS or any other for that matter.Note the lamp In front of the white wall, or is Nxt saying the background would be reflected in the lamp shade too, because of the material?

This illustrates my point better.

I added a "No Transparent Alpha" switch in the Object Properties a while back.

Got it takes, works like a dream.

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Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"Yes, the glass material translated as Refractive automatically."
Dec 23, 2020
Roy Hirshkowitz replied to Roy Hirshkowitz's discussion AccuRender Studio
"Yeah-- like I mentioned the caustics are accurate but could be annoying.  Things that might alter it include changing the sun angle so it's not striking the chair's metal surfaces so directly, changing the roughness of the chair…"
Dec 23, 2020
Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"Here's the latest render using metallic materials. The chrome now looks a lot better. I do feel though that the reflected light on the back wall is too bright."
Dec 23, 2020
Roy Hirshkowitz replied to Roy Hirshkowitz's discussion AccuRender Studio
"Ah-- so that's a function of the material type.  The standard material won't give you a mirror anymore.  You need to change the material to metallic and you should get something more familiar.  Use the Type popdown on the…"
Dec 18, 2020
Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"Pacing a mirror on the back wall (reflections = 1.0, noise = 0.0), you can see the difference more clearly (top image is nXt)."
Dec 18, 2020
Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"You can see from these two images that there is definitely something wrong with reflective surfaces. It appears the light is being reflected, but not objects or textures. In the nXt version (top image), the carpet texture is being reflected in the…"
Dec 18, 2020
Roy Hirshkowitz replied to Roy Hirshkowitz's discussion AccuRender Studio
"It's interesting-- overall the quality of this interior is very high for that short amount of processing, and may be acceptable for certain scenes.  In this one, however, there are some reflective caustics that are taking longer to…"
Dec 17, 2020
Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"ARDECAL now works. Here's the image after 10 minutes of rendering. I do have a slight concern that reflective surfaces seem rather dull. This is particularly evident on the end frame of the desk and the base of the chair."
Dec 17, 2020

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