Learn more about underlying GPU hardware here. Modern architectures – Fermi, Kepler, and Maxwell included – include dedicated tessellation units that allow for independent processing of tessellated objects. The automation of tessellation helps streamline production of high-fidelity, realistic graphics and avoids increasing development overhead. NVidia separately made clear that tessellation is often heavily automated by the underlying framework, but still requires fine-tuning by technical artists in-house. In a practical application, this is noticeable when observing a flat wall in-game that has a brick texture applied to it Epic could extrude the wall's triangles, producing an appearance that the wall is modeled with depth corresponding to the protruding bricks. Lighting and shadowing can work with those shapes to sell the final look.” Displacement and tessellation allow us to increase triangle density and then push and pull those triangles in, out, to the sides to get those shapes to come off of that surface. What you'll never get is a silhouette off of that kind of technique. You can do a lot of shader tricks to make it look better – what we call 'bump offset,' where we shift the location of pixels based on the camera angle – and that can give you the sense that the bricks have depth and are coming out of the surface. A small object far away doesn't need to spend performance for. “Epic biases displacement in tessellation based on camera distance. We asked whether tessellation could be impacted by camera angle or distance, curious as to techniques to create false depth to surfaces without consuming too many system resources. Willard outlines boulders as an easy example, as seen here: Dicing objects in this fashion allows for more curvature, bumps, gouges, and so forth. This effect was produced using displacement mapping that ultimately gets rendered by the GPU, assisting in the dicing of objects into more triangles. Some readers may remember the Samaritan demo, a video showcasing rocky extrusion from a human character's face. This topic was first brought to Epic Games by nVidia nearing the end of the development cycle for Unreal Engine 3. This not only makes the surface look higher resolution, bumps and hills and valleys that weren't there before. When we do that, that allows us to do things like displacement or smoothing and increase the apparent detail. “Tessellation is a way of doubling on the graphics hardware – so what was two triangles becomes four, what was eight becomes sixteen, and so on. When we asked for a top-level definition of tessellation, Willard explained (emphasis is ours): Alan Willard Interview – What Is Tessellation?Īt a top-level, Willard explains that surfaces and walls (think of these as a flat surface) are built out of “quads.” Quads consist of two triangles that are “butted-up together” to make a square.
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