Tim Attwood <tim### [at] comcastnet> wrote:
> It does seem to make some speckling of shadows in some
> cases where scenes in 3.6 did not.

  Do the speckes disappear if you specify an ior or reflection for the objects?

  Could you build a minimal scene which demonstrates the problem?

-- 
                                                          - Warp

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Warp wrote:
>  In the new beta the behavior of the maximum trace level has been
> changed a bit. Now the trace level is *not* incremented for objects
> which do not have reflection nor ior (but which may be transparent or
> semi-transparent).

Will there be a new keyword for specifying the max desired number of 
transparent surfaces passed through (default=infinite)? If not, how can it 
be avoided that scenes that rendered fast before (with acceptable artifacts) 
will render extremely slow with the new behavior?

Rune
-- 
http://runevision.com

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>  Do the speckes disappear if you specify an ior or reflection for the 
> objects?

It looks like the speckles are there even with ior or reflection or with
max_trace_level boosted.

>  Could you build a minimal scene which demonstrates the problem?

Sure, this shadow looks banded by coincident surfaces in 3.7
but not in 3.6

#declare testmat = material { texture {
      pigment {color <1,0,0> transmit 0.5}
      // finish { reflection 0.1 }
   }
   // interior{ior 1.1}
};
camera { location  <1.0, 2.0, -4.0>
   direction 1.5*z
   right     x*image_width/image_height
   look_at   <1.0, -0.2,  0.0>
   angle 30 }
light_source {<-10, 10, -5> color rgb <1, 1, 1>}
plane {y,-1 pigment{rgb <1,1,1>}}
union {
   sphere {<0.0,0,0>,0.5 material{testmat}}
   sphere {<0.1,0,0>,0.5 material{testmat}}
   sphere {<0.2,0,0>,0.5 material{testmat}}
   sphere {<0.3,0,0>,0.5 material{testmat}}
   sphere {<0.4,0,0>,0.5 material{testmat}}
   sphere {<0.5,0,0>,0.5 material{testmat}}
}

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Warp wrote:
>   Actually my intention was not to ask "test with tons of objects put one in
> front of the other, as many as you can, to see that it indeed works", but to
> test that the feature didn't break any existing scenes (eg. by crashing the
> program or causing visual artifacts). :)
> 

You should know that posting "Please test this" in these newsgroups is 
tantamount to saying "Please try to break this" :)

-- 
...Ben Chambers
www.pacificwebguy.com

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Tim Attwood <tim### [at] comcastnet> wrote:
> >  Could you build a minimal scene which demonstrates the problem?

> Sure, this shadow looks banded by coincident surfaces in 3.7
> but not in 3.6

  It doesn't seem to be related to the max trace patch because disabling it
doesn't change the problem.

  You should make a proper bug report.

-- 
                                                          - Warp

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Rune <new### [at] runevisioncom> wrote:
> Will there be a new keyword for specifying the max desired number of 
> transparent surfaces passed through (default=infinite)? If not, how can it 
> be avoided that scenes that rendered fast before (with acceptable artifacts) 
> will render extremely slow with the new behavior?

  You think it's necessary? Any suggestions?

-- 
                                                          - Warp

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Warp wrote:
> Rune <new### [at] runevisioncom> wrote:
>> Will there be a new keyword for specifying the max desired number of
>> transparent surfaces passed through (default=infinite)? If not, how
>> can it be avoided that scenes that rendered fast before (with
>> acceptable artifacts) will render extremely slow with the new
>> behavior?
>
>  You think it's necessary?

I don't have particular scenes in mind, but the need for it is just as real 
as a ned for an adjustable max_trace_level. If it was just a matter of 
avoiding infinite trace loops, a fixed max_trace_level of, say 255, with no 
option of setting it lower, would be fine. But it's not just about that, and 
this is no different if the ray goes straight through or bended.

> Any suggestions?

I don't know. max_passthrough_level ?

Rune
-- 
http://runevision.com

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Rune <new### [at] runevisioncom> wrote:
> I don't have particular scenes in mind, but the need for it is just as real 
> as a ned for an adjustable max_trace_level. If it was just a matter of 
> avoiding infinite trace loops, a fixed max_trace_level of, say 255, with no 
> option of setting it lower, would be fine. But it's not just about that, and 
> this is no different if the ray goes straight through or bended.

  If the trace level was not limited then reflecting/refracting objects
could cause an infinite loop. That's the main reason why the trace level
is limited.
  However, objects which do not reflect nor refract cannot cause an infinite
loop.

  But perhaps it might be a good idea to be able to limit the number of
transparent objects traced, if needed...

-- 
                                                          - Warp

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>  You should make a proper bug report.
OK, I put in a bugreport.

Thanks for the work on pass-thru rays.
Might be nice to be able to put a number on it
like max_trace_level, but overall it seems
like a good idea.

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"Chambers" <ben### [at] pacificwebguycom> schreef in bericht 
news:46dd0474@news.povray.org...

> You should know that posting "Please test this" in these newsgroups is 
> tantamount to saying "Please try to break this" :)
>

...and that is good scientific practice, according to Karl Popper   :-)

Thomas

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