Hi All,

I have a question regarding the creation of a shader in C5Pro: Is there a way of making a gradient shader for a surface that goes from white opaque in the center to fully transparent on the edge (see illustration)? I want to create a floor of 1000mm x 1000mm where I can see cast shadows but no horizon. Thanks. Happy christmas to you all. Johannes

If you just want to get rid of the horizon, there are maybe other approaches that would require less of your render time too. There is the 'shadow catcher' thing that might do what you want. Are you rendering with raytrace, or do you want to use GI and IL? Do you want to combine your render with a existing background? Or is it just the edge you do not want? If you check the 'packaging' scenes in the Wizard, you will see that there are certain ways of creating a 'white room' that might be usable for your situation too.

Johannes. What an intersting one. No solution BUT it looks like it MAY be somthing like applying the Veloute Tools 2d Gradient on a plane. Using the Circular zero-one pattern and checking invert. It' just a guess and not much help if you don't have the Velout plug in. Will look at more tomorrow.

Hoofd: I would use a white background, preferably with GI. I'd rather not go for actually building a white room like in the Packaging Scenes. Stupid question: what do you mean by "shadow catcher thing"? :) J

Attached Link: ShadersPlus @ www.digitalcarversguild.com

You can make anything a shadow catcher, but normally that works only with ray tracing. I you want to 'catch shadows' with GI you need the plugin from DCG that does just that (and lots and lots of other things). If you want just a white background, and a white floor, the horizon line should not be a problem at all. The 'building' of a white room could be just a bent plane from the spline modeller. Or a plane that bends downwards at the end, or something. Good luck! Hoof

I'd look at the shader catcher, or Shaders Plus GI Shadow Catcher route. You can also look at the Radial Gradient in Shader Ops. It does exactly what you've shown in your original diagram.

Regards,
Eric Winemiller
Digital Carvers Guild
Carrara plug-ins

Is this the result you want to get?

This is the object, an infinite plane, background = white, ambient light = 0, and no other lights. The infinite plane has Shaders Plus GI Shadow Catcher with Max Brightness set on 80%. The renderer is set on Sky Light = checked, Photon Count = 50000, Lighting Quality = Excellent, Accuracy = 4 pixels. It shows no horizon.

You could get away with using the built in Shadow Catcher if you went for normal lighting (no GI).

Regards,
Eric Winemiller
Digital Carvers Guild
Carrara plug-ins

You could also create texture maps for the transparency channel to achieve your goal of a fully transparent outer edge of your floor plane. - Dex

Like this?

The Blender is a curve filter on a Radial Gradient. A couple control points in the Filter control how much of the shader is which color. Copy the color channel to the Transparency channel with the colors reversed. If you wanted to get tricky, make the Blender a Reference Shader so you'd only haveto mess with it in one place to affect both the color and transparency channels. - Jasen.

Don't know if this .car will help or confuse? At least you will be able to look at all the adjustments in the various parts of the shader. I used the Shader Ops Radial Gradient. And it won't let me attach the .car file? Sorry.

Go to www.3dxtract.com---forums---Carrara--Radial Gradient. Where you will get access to the .car.

You can attach a .car, just change the extention to .txt and let the person know. R'Osity will transfer the file fine as long as it isn't too big.

Sorry Bluetone you have lost me. Do you mean change Radial Gradient.car to Radial Gradient.txt? And what person do I let know? Sorry if that all sounds dumb.

Yes. Renderosity's servers will not accept all file types, but certain ones they will, like .jpg, and .gif AND .txt. So, change "Radial Gradient.car" to "Radial Gradient.txt". Then Renderosity's servers will accept the file type and you can updload it to the site as a link in your message. Then whoever wants to download the file can and then change it back to "Radial Gradient.car" and it will work.

Thanks Bluetone--here goes--

Thanks everyone!! Johannes

bwtr: The Curve Filter in your file looks good. But under the filter is just a solid color rather than a radial gradient; did you use a plugin for the gradient? I used C5's radial gradient in mine. You may want to use the alpha channel rather than transparency when using this technique. Using the alpha channel you can just put a solid color in the color channel - you don't have to do the "brightness" balancing act that the transparency channel requires. This technique is very useful for particle emitter objects. Attached is a file where I get a little silly with the Curve Filter. - Jasen.

And here's a render from the above .car file. The center is solid, non-transparent, followed by a turbulent transparency section, then fully transparent to the edge. In the color channel is a turbulent center, solid red (blended smoothly with black to balance with the transparency), then solid black to make the edge fully transparent. - Jasen.

JasenJ1. I used the Shader Ops plugin Radial Grad. You say you used C5 Radial Grad?--I can only find Spherical Gradient?
I have gone through your three shaders on the .car and I think it's all to clever my mind to grasp! I guess it's because I would not think of what you wanted to attain in a million years! What a lot of clever people in 3D. OK I found the C5 ADJUSTABLE gradient--whacco you beaut!

Message edited on: 12/21/2005 16:05