Visible but not visible ??!

homey_jay

Is there any way to have a refelecting object in C8.5 that causing reflecttions in the render on other objects but itself actually be invisible in the render?

eg I'm using a large surface with a reflection map to give interesting reflections on objects but the damned thing is visible absolutely everywhere when rendered!

Jonstark

I think there's a way to do this using a combination of backdrop and background (in scene tab of the assembly room).  I'm thinking you'd put the reflection map in the background channel and then a different map (like an hdri or similar) of the actual scene in the backdrop channel.

Edit:  yup, just tested and this could work. I threw a texture map of one of my character's facial spec maps into the baground channel, then put in a color in the backdrop channel, and put a reflective sphere in the scene, seems to work ok.

Dartanbeck

Also, in case you're thinking a different thing:

In the shader of the invisible object, instead of use Alpha channel to reduce visibility, use Transparency. In Intensity use a value 1-100 slider and set it up as high as 100 (invisible)

You can still use shininess and highlights and reflections, etc., while the thing is still clear.

homey_jay

Thanks - that trick with the transparancy worked perfectly!

Dartanbeck

homey_jay said:

Thanks - that trick with the transparancy worked perfectly!

My pleasure. Since that worked, I'd also like to suggest trying out some of the included shader examples in the browser.

"Glass" > "Clear" is an excellent place to start, because it has a nice basic Glass setup, complete with refraction, etc.,

But to use Refraction effectively, you need two layers of mesh, or the refractive calculations will continue on - as if the depth of the refractive material is still there.

For example, for glass, we need a lyer of mesh for the face surface, and another to determine the thickness of the glass.

A single sphere with no thickness would therefore be a solid glass sphere. Add thickness (either in the model room, or by duplicating (Ctrl+D) the original and scaling in or out) and instead we'll have a shere made of 'x' thickness of glass, 'x' = the distance between the two spheres ;)

Fun stuff!

===========================================

Reflection vs Gloss

Sometimes we don't really even 'need' reflections, but just some good ol' shininess! For that, just try a high value (or bright color) for the Highlight channel, and somewhere around 1-100 = 25 for shininess, then adjust upward very slightly (up to 28 - 35) for tighter shines or downward (10 - 18) for more highlight coverage.

Trying this without any reflection can be helpful to make a surface look almost as if it is reflective without calculating for reflections. But sometimes we just really need those reflections - like some of the metals shaders rely on reflection to get the color, since color = none, or some other value (instead of color). 

Just some more fun things to consider.

 

homey_jay

Awesome tips, many thanks! Playing with this right now!