How do you render an alpha pass

[mxcreations]

Render Elements Panel and Rollout



Main toolbar > Render Scene button > Render Scene dialog > Render Elements panel > Render Elements rollout

Rendering menu > Render > Render Scene dialog > Render Elements panel > Render Elements rollout

Rendering to elements lets you separate various information in the rendering into individual image files. This can be useful when you work with some image-processing or special-effects software. You can later do compositing with the element renderings.

These are the elements you can choose to render separately:



Specular: The specular component of the rendering.
Diffuse: The diffuse component of the rendering.
The Diffuse element displays an additional Diffuse Texture Element rollout (http://diffuse_texture_element_rollout.html).
Self-Illumination: The self-illumination component of the rendering.
Reflection: The reflections in the rendering.
Refraction: The refractions in the rendering.
Shadow: The shadows in the rendering. This element saves black-and-white shadows only. See the later section on "Compositing Rendered Elements."
Atmosphere: The atmospheric effects in the rendering.
Blend: A custom combination of the previous elements.















The Blend element displays an additional Blend Element Parameters rollout (http://blend_element_parameters_rollout.html).
Z Depth: A grayscale representation of the Z depth, or depth within the view, of objects within the scene. The nearest objects appear in white, and the depth of the scene in black. Intermediate objects are in gray, the darker the deeper the object is, within the view.
The Z Depth element displays an additional Z Element Parameters rollout (http://z_element_parameters_rollout.html).
Alpha: A grayscale representation of the alpha channel, or transparency, of the scene. Transparent pixels appear in white (value=255) and opaque in black (value=0). Translucent pixels appear in gray. The darker the pixel, the more transparent it is.
The alpha channel can be useful when you composite elements.
Background: The background of the scene.
Other elements do not include the scene background. Include this element if you want to use the background in compositing.
The background is not trimmed against geometry, so elements should be composited over the background. See the later section on "Compositing Rendered Elements."
Ink: The Ink component (borders) of Ink 'n Paint materials (http://ink_n_paint_material.html).
Paint: The Paint component (surfaces) of Ink 'n Paint materials.
Lighting: The effect of direct and indirect lights and shadows in the scene.
The Lighting element displays an additional Lighting Texture Element rollout (http://lighting_texture_element_rollout.html).
Matte: Renders a matte mask, based on selected objects, material effects channel (effect IDs), or G-Buffer IDs.
The Matte element displays an additional Matte Texture Element rollout (http://matte_texture_element_rollout.html).
When you render one or more elements, a normal complete rendering is also generated. In fact, the element renderings are generated during the same rendering pass, so rendering elements costs little extra render time.

Rendering to elements is available only when you do production rendering with the default scanline renderer (http://default_scanline_renderer_rollout.html) or the mental ray renderer (http://mental_ray_renderer.html).

Note: The default scanline renderer supports a maximum of 32 render elements per scene. The mental ray renderer does not limit the number of render elements. If you're using a third-party renderer, check the product documentation for a possible limit on the number of render elements.
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NOW!
How did I get to this info??? > PRESS F1 > SEARCH "render pass"
It's that simple dude!

[3Darklight]

the Render Elements panel in the Render Window has everything you need.
where are you gonna do your compositing? after effects? combustion? or just stills in photoshop. depending on the program you'll have to save the file in a different format. RLA works with the adobe apps, RPF is perfect for combustion (might work with after effects too, haven't used it since version 4).

[sadghost]

cool sweet ... It's time to work thanks guys!

Yeah I did see it . but sometimes you might get a diffrent or better technique from other people.. or another approach, that's why I asked.

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