POV-Ray : Newsgroups : povray.newusers : Transparent Objects Become Black : Re: Transparent Objects Become Black Server Time
9 Dec 2021 07:54:29 EST (-0500)
  Re: Transparent Objects Become Black  
From: Alain Martel
Date: 11 Nov 2021 12:08:51
Message: <618d4e23$1@news.povray.org>
Le 2021-11-11 à 08:06, bubble_person a écrit :
> Hello Forum,
> 
> I am relatively new to POV-RAY, but have a functional script .
> 
> I am simulating air bubbles in a glass tube full of gel.  I am running into a
> funny problem where, if I add too many bubbles to the script, they go from being
> transparent and rendered correctly, to a completely opaque, black object through
> which no light shines.
> 
> Things that don't seem to work:
> 
> 1) Increasing the  max_trace_level
> 
> 2) I have tried to be sure that the inner surface of the gel is not in contact
> with the air bubble by reducing the bubble radius by epsilon (.0001).  Oddly
> enough, the script with up to 4 bubbles works only when the two surfaces are
> coincident, and subtracting an epsilon value (.0001,.001,.01) causes the bubbles
> to turn black, no matter the number.
> 
> I would love your input on this issue as I am stumped.  I cannot figure out why
> this renders without issue when I only have a certain number of objects defined.
> 
> 
> The order of my file:
> 
> In my scene, centered at the origin, I have bubbles, inside of gel, inside of a
> glass tube, inside of water, inside of a plexiglass cylinder.
> 
> My code
> 
> 1) I define variables, set trace level, and place the camera
> 
> 2) I create a distributed area light source on a rectangular box
> 
> 3) I define the bubbles I want in the gel
> 
> 4) I create the glass tube into which the gel will sit
> 
> 5) I create the gel region with voids into which the bubbles sit.
> 
> 6) I then add water around the glass tube, and then a plexiglass perimeter.
> 
> 
> 
> 

The first thing that I would to would be to increase max_trace_level 
further still. It can go up to 255.

Note : Your area_light is oblique. If you want it to be flat, then, it's 
size should be something like this :
area_light 160*x 200*z 65 65
adaptive 0 // start with zero, then, increase if needed
Size of area_light adjusted to match the light_box dimensions.

During testing, you should disable the area_light. It makes testing and 
debugging faster.

The 100 by 100 get silently increased to 129 by 129 when adaptive is 
used. That increase DO NOT affect the rendering time.

Using dispersion 1 is the same as not using dispersion. It must be 
slightly different than 1. Realistic values are usually in the 1.01 to 
1.08. Values less than 1 result in inverted dispersion.

You are using fade_power 1000 !? You should use 1 or 1001.
Using 1000 may cause some issues.


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