Compositing and Rendering Chakrit Watcharopas Reference: The Essential Blender: The Official Guide to 3D Creation with the Blender Open Source Suite   Author Roland Hess Publisher No Starch Press Publication Date 2007-09-27 Also from: http://blenderunderground.com/2008/03/31/introduction-to-composite-nodes-part-1/

Why Composite?

Why Composite? (2) Although rendering might seem to be done, in a real production environment you would almost certainly have to color correct or composite the render with a pre-created background, or possibly even put it together with several different renders, building a final image in layers Though possible to add all elements of finished scene into a single render, it is an inefficient and time consuming approach to a production

Render Passes Left to Right, Top to Bottom: Combined, Alpha, Z Buffer, Color, Diffuse, Specular, Shadow, Ambient Occlusion, Reflection.

Render Passes (2) Blender’s Composite Nodes give the user access to data from its render passes When Blender calculates things like shadows or specular highlights, it stores the results as pixel data Images will be combined later using pixel math

Render Passes (3) You can access each of these passes individually, modify them, and put them back together in whatever way you see fit Above process is known as compositing The primary definition of a composite is something made up of differing parts, combined to make a whole

Render Passes (4) In Blender, when you press F12 and render your scene, what you’re seeing is a composite of render passes – a set of separate images combined together into one final With CompositeNodes, you can control how these render passes get assembled, and what happens to them along the way

CompositeNodes Combined – This is the renderer’s composite of all the render passes

CompositeNodes (2) Alpha – This pass is an 8-bit graphic representing the combined render’s transparency information White pixels represent full opacity and black pixels indicate full transparency

CompositeNodes (3) Z-buffer – You might not be able to see the data represented of the scene depth here Z-buffer information is stored as a 32 bit floating point number

CompositeNodes (4) Color – This is an RGB color mask containing information for each object in the scene

CompositeNodes (5) Diffuse – This pass contains all shading and color information from lighting calculations in the scene

CompositeNodes (6) Specular – The information generated from all materials’ specular shaders are contained in this pass

CompositeNodes (7) Shadow – For ray traced or buffered shadows, this pass stores the shadow data for the scene

CompositeNodes (8) Ambient Occlusion (AO) – This pass is the result of a separate pass using the AO algorithm

CompositeNodes (9) Reflection – Data generated from ray traced reflections are stored in this pass

Render Layers In the Render Layers panel of the Scene buttons (F10) are buttons for activating the various passes Left: Render Layers panel with render passes selected. Right: Render Layer node with corresponding render pass points

Setting Up for Node Editing Node editor with composite nodes button selected and “Use Nodes” button active.

Setting Up for Node Editing (2) Once you have the Node editor active, you’ll need to select the Composite Nodes button at the bottom, and turn on the Use Nodes button

Setting Up for Node Editing (3) The last step is turning on “Do Composite” in the Anim panel of the Scene buttons – if you don’t, all the node editing in the world won’t affect your final render Anim panel with “Do Composite” active