POV - Dark areas where transparent objects overlap - ior10.zip (0/1)

POV - Dark areas where transparent objects overlap - ior10.zip (0/1)

Post by Rune Winsev » Wed, 31 May 2000 04:00:00



Hi,

I've made a wine glass with our CAD program and exported to POV as a
mesh. Alone this glass looks quite all right, but if I place two of
these glasses so that the closest partially obscure the other things
get really ugly. Where the glasses overlap the result is a dark area.
First I thought that this was some strange refraction related mistake,
but even if I turned off refraction entirely, the atrifact persisted.

I have attached the .pov file complete with two glasses placed behind
eachother. I don't know how to describe the artifact so if you would
please take a look. (The .pov file is on 3.01 format, but 3.1 versions
should read it all right).

I'm sure I've done something stupid because this can't be a POV bug.
After all, POV is well-tested raytracer and thousands of people are
using it. So it must be me ;-)

Thanks for any help!

-Rune Winsevik

 
 
 

POV - Dark areas where transparent objects overlap - ior10.zip (0/1)

Post by Ken » Wed, 31 May 2000 04:00:00



> Hi,

> I've made a wine glass with our CAD program and exported to POV as a
> mesh. Alone this glass looks quite all right, but if I place two of
> these glasses so that the closest partially obscure the other things
> get really ugly. Where the glasses overlap the result is a dark area.
> First I thought that this was some strange refraction related mistake,
> but even if I turned off refraction entirely, the atrifact persisted.

> I have attached the .pov file complete with two glasses placed behind
> eachother. I don't know how to describe the artifact so if you would
> please take a look. (The .pov file is on 3.01 format, but 3.1 versions
> should read it all right).

You forgot the attachment :) Anyway I suspect that you need to specify
a max_trace_level in your global settings block.

global_settings { max_trace_level 20 }

The default max_trace_level is 5 which is often not enough for
overlapping transparent surfaces. I suggest you start with 20
and see if that cures your problem. If not you can raise it to
any higher value you wish.

--
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

 
 
 

POV - Dark areas where transparent objects overlap - ior10.zip (0/1)

Post by Rune Winsev » Thu, 01 Jun 2000 04:00:00




>> Hi,

>> I've made a wine glass with our CAD program and exported to POV as a
>> mesh. Alone this glass looks quite all right, but if I place two of
>> these glasses so that the closest partially obscure the other things
>> get really ugly. Where the glasses overlap the result is a dark area.
>> First I thought that this was some strange refraction related mistake,
>> but even if I turned off refraction entirely, the atrifact persisted.

>> I have attached the .pov file complete with two glasses placed behind
>> eachother. I don't know how to describe the artifact so if you would
>> please take a look. (The .pov file is on 3.01 format, but 3.1 versions
>> should read it all right).

>You forgot the attachment :) Anyway I suspect that you need to specify
>a max_trace_level in your global settings block.

>global_settings { max_trace_level 20 }

>The default max_trace_level is 5 which is often not enough for
>overlapping transparent surfaces. I suggest you start with 20
>and see if that cures your problem. If not you can raise it to
>any higher value you wish.

Yes, I messed up with the attachment. My news client (Forte Agent)
refused to send a binary attachment to a non-binary group...

Anyway, you're absolutely right! setting the max_trace_level fixed the
problem!

Thank you very much!

-Rune

 
 
 

POV - Dark areas where transparent objects overlap - ior10.zip (0/1)

Post by typ.. » Sat, 03 Jun 2000 04:00:00


I cannot believe it.

I just posted a problem to this group very similar to this.

I had scanned the articles before posting and searched using what terms
I could thing of but I missed this thread.

Unbelievable.

This solution solved my hollow-glass-within-glass trouble on the very
first try.

I am indebted to you!

Thanks,
TypoII
Frederick, MD




> > Hi,

> > I've made a wine glass with our CAD program and exported to POV as a
> > mesh. Alone this glass looks quite all right, but if I place two of
> > these glasses so that the closest partially obscure the other things
> > get really ugly. Where the glasses overlap the result is a dark
area.
> > First I thought that this was some strange refraction related
mistake,
> > but even if I turned off refraction entirely, the atrifact
persisted.

> > I have attached the .pov file complete with two glasses placed
behind
> > eachother. I don't know how to describe the artifact so if you would
> > please take a look. (The .pov file is on 3.01 format, but 3.1
versions
> > should read it all right).

> You forgot the attachment :) Anyway I suspect that you need to specify
> a max_trace_level in your global settings block.

> global_settings { max_trace_level 20 }

> The default max_trace_level is 5 which is often not enough for
> overlapping transparent surfaces. I suggest you start with 20
> and see if that cures your problem. If not you can raise it to
> any higher value you wish.

> --
> Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing
Links:
> http://home.pacbell.net/tylereng/index.html

http://www.povray.org/links/

Sent via Deja.com http://www.deja.com/
Before you buy.

 
 
 

POV - Dark areas where transparent objects overlap - ior10.zip (0/1)

Post by Ken » Sat, 03 Jun 2000 04:00:00



> I cannot believe it.

> I just posted a problem to this group very similar to this.

> I had scanned the articles before posting and searched using what terms
> I could thing of but I missed this thread.

> Unbelievable.

> This solution solved my hollow-glass-within-glass trouble on the very
> first try.

> I am indebted to you!

I am happy my indirect help was of use to you :)

--
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

 
 
 

1. POV - Dark areas where transparent objects overlap

Hi,

I've made a wine glass with our CAD program and exported to POV as a
mesh. Alone this glass looks quite all right, but if I place two of
these glasses so that the closest partially obscure the other things
get really ugly. Where the glasses overlap the result is a dark area.
First I thought that this was some strange refraction related mistake,
but even if I turned off refraction entirely, the atrifact persisted.

I have a zipped .pov file here which I would like to send to anybody
caring to help me, but I won't post it in this non-binary group.

I'm sure I've done something stupid because this can't be a POV bug.
After all, POV is well-tested raytracer and thousands of people are
using it. So it must be me ;-)

Thanks for any help!

-Rune Winsevik

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