Bob Hughes wrote:
> 
> Mike's had a setback with it too, was talking about it Saturday night
> at POV-Ray Chat on AOL.  He was encountering a totally black media
> after hiw most recent compilation.  No idea if any relation to
> possible other problems but seems something might not be correct in
> the code I guess.  He'll have to speak for himself, all I'd have to
> say is totally wild conjectures (duh).
> 
> Bob

  My point to Tony may not have been altogether clear either. I don't care
right now how the media appears. It is the way the light sources themselves
are acting that I am finding disturbing. I can adjust the media but I cannot
recode the way the light sources are working in the scene.

-- 
Ken Tyler
1100+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html

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> My point to Tony may not have been altogether clear either. I don't care
> right now how the media appears. It is the way the light sources themselves
> are acting that I am finding disturbing. I can adjust the media but I cannot
> recode the way the light sources are working in the scene.

There really isn't anything going on with the lighting here.  What's happening
is that you are specifying a min of 10 samples and a max of 100.  Up to the
minimum the new method is being used.  The next 90 are being cast in the same
spot (the end of the interval).  When it's all averaged out you end up with
bright areas at the end of the interval.

I could simply fix this by using the max samples or ignoring them altogether.

-Mike

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> Mike's had a setback with it too, was talking about it Saturday night
> at POV-Ray Chat on AOL.  He was encountering a totally black media
> after hiw most recent compilation.

I got that part fixed.  There's something in the code I still don't
understand, as I can't get supersampling to work yet.

At this point I'm thinking of just scrapping backwards compatibility for
now and try to just get it to work the way I want it to.  In the meantime
I might update the one I released to add a fix for the problem Ken
pointed out and to change the new keywords.

-Mike

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Good idea.

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I also tried making a variety of modifications to media, including evenly
spaced samples and supersampling, but I couldn't get supersampling to work
properly either.  I now know what I was doing wrong.  Make sure that when
you super-sample, you give the super-samples less weight in the average.
I.E. if you add a new sample between two existing samples, the new weights
of the existing samples plus the weight of the new sample should still add
up to the sum of the original weights of the two original samples.  Ok...
that sounds a lot more confusing than I intended.

-Nathan

Mike <pov### [at] aolcom> wrote in message news:37EF0DCB.98DCDE0D@aol.com...
> > Mike's had a setback with it too, was talking about it Saturday night
> > at POV-Ray Chat on AOL.  He was encountering a totally black media
> > after hiw most recent compilation.
>
> I got that part fixed.  There's something in the code I still don't
> understand, as I can't get supersampling to work yet.
>
> At this point I'm thinking of just scrapping backwards compatibility for
> now and try to just get it to work the way I want it to.  In the meantime
> I might update the one I released to add a fix for the problem Ken
> pointed out and to change the new keywords.
>
> -Mike
>
>

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>I also tried making a variety of modifications to media, including evenly
>spaced samples and supersampling, but I couldn't get supersampling to work
>properly either.  I now know what I was doing wrong.  Make sure that when
>you super-sample, you give the super-samples less weight in the average.
>I.E. if you add a new sample between two existing samples, the new weights
>of the existing samples plus the weight of the new sample should still add
>up to the sum of the original weights of the two original samples.  Ok...
>that sounds a lot more confusing than I intended.


Makes perfect sense to me.

A1 = original pixel 1
B1 = original pixel 2
A2 = new pixel 1
B2 = new pixel 2
C2 = supersampled pixel between A2 and B2

A1+B1 = A2+C2+B2

Right?

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TonyB wrote:
> 
> >I also tried making a variety of modifications to media, including evenly
> >spaced samples and supersampling, but I couldn't get supersampling to work
> >properly either.  I now know what I was doing wrong.  Make sure that when
> >you super-sample, you give the super-samples less weight in the average.
> >I.E. if you add a new sample between two existing samples, the new weights
> >of the existing samples plus the weight of the new sample should still add
> >up to the sum of the original weights of the two original samples.  Ok...
> >that sounds a lot more confusing than I intended.
> 
> Makes perfect sense to me.
> 
> A1 = original pixel 1
> B1 = original pixel 2
> A2 = new pixel 1
> B2 = new pixel 2
> C2 = supersampled pixel between A2 and B2
> 
> A1+B1 = A2+C2+B2
> 
> Right?

	Well, not exactly or you wouldn't need the supersampled pixel at all :)
but ideally yes (and as far as weight is concerned, yes)

		Jerome

-- 
*******************************

* they'll tell you what can't * mailto:ber### [at] inamecom
* be done and why...          * http://www.enst.fr/~jberger
* Then do it.                 *
*******************************

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> I also tried making a variety of modifications to media, including evenly
> spaced samples and supersampling, but I couldn't get supersampling to work
> properly either.  I now know what I was doing wrong.  Make sure that when
> you super-sample, you give the super-samples less weight in the average.
> I.E. if you add a new sample between two existing samples, the new weights
> of the existing samples plus the weight of the new sample should still add
> up to the sum of the original weights of the two original samples.  Ok...
> that sounds a lot more confusing than I intended.

I think I know what you are saying, but the way I'm doing it fits in with the
new sample_media function, so each time a supersample is taken it's added into
the total emission.  Then later it's divided by the total number of samples for
that interval.

I think I found the problem though.  I was looking through one of the functions
for where the values are added and noticed the variable d0 was still being used
even though I took d1 out of the function.  I can only assume it's value is 0
because I forgot to pass it into the function.  I'm going to try to fix that
and I hope, oh how I hope it works!  I've spent so much time on this and really
haven't got anywhere.

-Mike

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Mike <pov### [at] aolcom> wrote in message news:37F03EC1.A53D7734@aol.com...
> I think I know what you are saying, but the way I'm doing it fits in with
the
> new sample_media function, so each time a supersample is taken it's added
into
> the total emission.  Then later it's divided by the total number of
samples for
> that interval.
>

That will cause a problem, though.  Uneven sampling (which is the result of
supersampling) needs uneven weights for the averaging process.  A simple
sum-and-divide will not give desired results.  I know, since I tried it.
;-)

-Nathan

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> That will cause a problem, though.  Uneven sampling (which is the result of
> supersampling) needs uneven weights for the averaging process.  A simple
> sum-and-divide will not give desired results.  I know, since I tried it.
> ;-)

I can only assume you are correct since I can't get it to work. I'm still
trying to get a handle on how everything goes together in media.c.

-Mike

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