Hi

I'm making a forest using billboards - my billboards are two orthogonal faces with the same image on it, and one pointing directly at the camera.

I'm using png images with an object surrounded by transparency.  The image shows a test landscape with two types of tree.

When I raytrace I get many elements drawn black.  Why is this, I wonder?  Radiosity doesn't change it.  Could it be a lack of light?

The scene looks fine in 3DC.  Any ideas?

George

could you send me the scene? i will open it and take a look...not sure whats going on there, but would love to see why its happening..if not, please let me know what you find out...i havent done anything like that in POV yet..

a total guess - no pov at the moment to test it on...

do the "black trees" overlap another tree ? if so this might (the guess bit) cause some problems. Try moving one of your "black trees" away slightly so it is not touching any other.....

Again - this is just a guess

how come your pov is working ? altered system date ?

nope

just downloaded rc5 - and tested my guess.

I am getting the same problem - touching or not......

Blayd

I'll send you the file to make you happy.  You might have to move the camera around to get it looking like this if I've moved it.  Cant remember

Alan

Yes smarty pants I've altered my system date.  10M over a dialup every week is getting boring. Don't tell anyone else.

George

solved it by looking in newsgroup archives.

You have to increase the value of

max_trace_level in the global settings.

Anyone using many transparent textures overlapping should read the help file on this.

Thanks for responding.  I've sent you the file anyway B.
George

George,
I just now saw your post on this subject. Wish I had seen it earlier, as I could have saved you a little time with the searching of the news groups.
This "artifact" problem occurs when there are lots of overlapping transparent textures. It can be anything like smoke, trees, multiple cloud layers, etc.
Hmm, someone should write a max_trace_level tutorial for Pov to explain why this happens and how to correct it.
Anyway, I'm glad you got it figured out. Now, back to my rat-killing(learning more about VB6)..........hehehe...  ;D

Les

Thanks for the information - don't blame you for the system date (I am getting fed-up of the downloads.... went a couple of weeks without it -  I just wish that British Telecom would get broardband out here into Wales... )

Wales!!! I was born There! Milfordhaven

     is that right?

Dimensions,

Lots of people are born here
Tom Jones, Berley Shassy, The Pope,The England football manager.....*

Not sure if you are you asking if this is where you were born, then again I can't remember where I was born, or where I was last night ......... ???


* Not everything on the internet is the total truth.

getting a tad off topic from my coal black sea black faces, as the scene in my original post was supposed to be _New South_ Wales :-)

George

George,

It may be worth reporting this to POVRay.org. But be warned, they may bite your head off. They don't like to hear about bugs (especially if they aren't)

Richard

wouldn't dare then :-)

It's not a bug and is in fact quite well documented in online help - once you've figured out where to look.

The only minor problem is that you can't render into the 3DC screen as you have to change the global settings in the povray file.  It would only be possible if one day the 3DC programmer decided this could be included on teh properties page of the model....

George

So, what is the issue? Why does it do this?

Richard

For faster rendering.  Better to look up max_trace_level in Povray help than ask me.  Here's the beginning...

"In scenes with many reflective and transparent surfaces POV-Ray can get bogged down tracing multiple reflections and refractions that contribute very little to the color of a particular pixel. The global setting max_trace_level defines the integer maximum number of recursive levels that POV-Ray will trace a ray."

I must admit I didn't study it enough to understand completely -  I just found a setting that worked.  Didn't seem to change the render time much in this case.  I don't know if BMRT has the same thing, either.  You already have to decide on your renderer when setting up a scene as it decides your choice of textures: so in effect the renderer is a property of the scene.  What I'm getting at is there must be other things in both BMRT and Povray that I've never heard of.  So is there an easy way to use them from 3dC without editing the Pov file itself by, for example, allowing the user to fill in a "global settings" box to be exported with the file?  Doesn't actually make it that much easier if you keep povray open...and you would spend all your time updating support for the renderers.

Getting into a bit of a ramble here.  Stop.

George