ok... why is it that my transparancies all turn black?.. this is supposed to be a semi-trans glass like pumpkin... but it's all black.. I have tried lighting.. camera angles... can't get it.. something I'm missing?

and here are my settings for the shader... something i'm missing here?

Hi....try turning color to value and keep it at 0% and in your transparency put the orange color.....I think this will do it..I do not have Carrara open to try it.....but if it does not work....I will open up carrara and find the right way. kirk saavedra www.shaders3d.com

Message edited on: 10/08/2004 22:17

Hi again...I just checked...The way i said was right..

kirk saavedra
www.shaders3d.com

Message edited on: 10/08/2004 22:19

In the render room.. have you made sure that 'transparency' and 'light through transparency' are checked?...

hmmm didn't work... :(

and here are the settings...

This just all seems wrong to me...?

If i want the "color" of the item to be orange.. well then I should set "color" to orange?

If I set the Trans to a color... how do i adj "how" transparent the item is?... if trans is a "color" then how can I make it very clear? or adj it to something that is only slightly clear?

did that make sence?

Message edited on: 10/09/2004 06:24

Can you attach your .car file to a message? This is a curious challenge.

Sticking a color in Transparency is a good way of getting colored light.... you've got that. :-) I copied your settings and set up your scene (as far as I could) and the only way I could get what you've got is... by setting my 'pumpkin' as a shadow catcher...? HTH, Mark

you also might try increasing your ray depth... with all those rays trying to bounce around in there, maybe none are getting back out

I couldn't reproduce this either. I think falcon has one possibility that makes the most sense. Turn that shadow catcher option off and you should be working fine. The only other thing I could think of was that it's the refraction but I couldn't get it to go black. I thought it might be refracting the black backdrop. -Kix

Here's my shader tree.

After taking a quick look again at your first post, you do have some orange showing up in it which makes me think it's not a shadow catcher deal. If you're comfortable with it, send me the file. -Kix

Hi here is a fast render to show you the way i said. kirk

The problem is in everyones shader tree it shows the reflection way to high.....this will not look good....turn it down to 3%.....trust me the color goes into the transparency section...not the coler section...the color section gets a value...and that is where you control how much the pumkin will look transparent. thanks kirk

Just playng around with it some more myself.

Ok, I've fussed with this enough. While I'm getting results that make some sense, I'm still stumped on the black pumpkin issue. I'm also still confused why 11% in the reflection channel is a problem. -Kix

Here's my shader for the last post. -Kix

well i got it... it was the shadow catcher... go figure

Very glad it came out! -Kix

now I have to fix it all up... :) thanks folks

Kixum, about the 11%, I think the 'value' value of the color in the transparancy channel is above 90%, so it adds up to more then 100%. Which is forbidden by the laws of nature, if I understand correctly.

Right. If 10% of your light bounces off the object, then you have only 90% left to either be absorbed by the surface, or to continue through the surface by transparency. To use an extreme example, you can't have an object that's 100% transparent and 100% reflective. That would mean that all of the light is passing through and all of the light is also bouncing off. I was never a Ray Dream user, but I played with it years ago and it handled this issue nicely - if I remember correctly, reflection and transparency were handled with a single slider control with two little arrows, one for transparency and one for reflection, Since they couldn't pass each other on the slider, it was impossible to get the percentages to overlap unrealisticallly. If you wanted more transparency you'd have to reduce the reflectivity. It was slick. I'm sure many of you are more familiar with this feature of Ray Dream. Still, in a more-strict physical model I would think that absorption of light should be handled in the same way, but as I recall it wasn't. - Joe

That's correct. If you look at the final shader tree I put together, the combination of transparency and reflection add up to something close to 100%. My loose interpretation was that reflection can have a large value. No biggy. As for Raydream vs. Carrara, you are again correct. Raydream would scale the other pertinant values as transparency was changed. That was removed from Carrara to give users more power over the shader engine. The shader tree shown here reproduces the effect of the Raydream transparency mechanism. You simply apply transparency using the slider at the bottom of the tree rather than in the transparency slider in the regular shader. All the other channels are set up as though you have no transparency at all. Color, reflection etc. are set they way you would like them with a non transparent object. One other note, you'll see that I cut back on the color channel extensively by mixing it with black a LOT in the previous post. Great comments! -Kix