I believe this is an important aspect to professional animation projects, which to my knowledge went mostly unaddressed and undiscussed since the creation of the Cycles engine. I’m hoping this will inspire a solution of any sort to the problem.
As everyone dealing in animation surely knows, most animated films are done in two steps: In primary stage, an extremely simplistic version of the scene is rendered, in order to preview how the animation looks like… whereas in the final stage, the animation is rendered with all visual features and effects enabled, to obtain the quality end product. This is done so the animation can be previewed quickly; You don’t want to waste hours / days rendering fancy materials and tons of particles and post-processing effects, just to see if the movement of a character during a certain sequence needs correcting… instead you render a simplified version of the world, which often involves disabling lighting altogether and even turning off textures in favor of flat surfaces, while some go as far as replacing their character mesh with a bunch of cubes attached to armature bones.
Cycles has a major issue here; Ray-tracing is so expensive that even when you disable every effect possible, down to using direct lighting exclusively (no bounces of any sort) and turning off caustics and shadows, it still takes too long to generate a preview. Even at 10 samples for 720p resolution, a single frame can take nearly a minute to render out… though even if it was faster it wouldn’t matter since everything is so grainy you can barely distinguish objects from one another! As an added annoyance, most settings need to be permanently changed during the preview then changed back before in the final render, so you must also note each one down to avoid losing your configuration.
Now I’m aware of the seemingly obvious solution: Render your animation test in Blender Internal, then the end product in Cycles. This might sound like an instant fix at first, but it’s not due to one reason: Cycles materials and settings differ from Blender Internal ones. Even if the 3D objects and meshes are the same, the differences in lighting and texturing can make a scene designed for Cycles impossible to discern in Blender Internal: You’d need new light entities since mesh lighting is Cycles exclusive (otherwise everything appears black), a different environment setup so the sky can be distinguished from the rest of the geometry, and if you want to have a textured preview then you must make entirely new materials for everything intended for BI. Obviously no one wants to setup the same scene in two different engines and do twice the work, just so they can get a simple preview render.
For those reasons, I propose a special render parameter for simplified rendering, for Cycles and if possible Blender Internal as well. My suggestion is simple: Just as you have the “wireframe” / “solid” / “textured” / “material” / “rendered” options for the viewport, offer those options at render time as well! This should allow us to render frames in under 1 second and instantly generate simple previews, without having to turn down dozens of settings per test or move between engines and even then get poor results.
I’m not sure if any Blender developers will read this, and I’d really like to get the suggestion out to them if possible. Until myself or anyone else does so, I’m curious what other artists think; Do you agree Blender needs to have this or a similar ability? Other than that, I’d like to know what workarounds people found within what Blender currently offers.
