Glossary/GPU/Rasterization

Rasterization

Rasterization is the rendering technique that projects triangles onto the screen grid and shades the covered pixels, and it drives nearly all real-time graphics.

Also known as raster rendering, raster

Measured by SystemCheck

Part of the four-stage run: a 60-second sustained CPU load reporting throughput, decay and consistency; a memory stage reporting bandwidth and latency; a calibrated GPU raster load reporting frame time, pacing and decay; and a path tracer reporting samples per second. The paragraphs below say which metric carries this term.

The pipeline transforms vertices into screen space, determines which pixels each triangle covers, and runs a fragment shader per covered pixel. It is fast because it never asks the physically correct question (what light actually reaches this point). It only asks which surface is visible and what colour to paint it.

That approximation is why raster rendering needs so many tricks: shadow maps, screen-space reflections, ambient occlusion, and baked lightmaps all exist to fake effects that follow naturally from tracing light. They are cheap and they are the reason a mid-range GPU can hold 144 fps.

SystemCheck's GPU stage is a rasterization workload. It applies calibrated raster pressure and measures frame time, frame pacing stability, and decay over the run, so it reports how your GPU behaves on the kind of work the overwhelming majority of games actually do, separately from the path-tracing stage that probes the ray-tracing pipeline.

Related terms

Ray tracingRay tracing computes lighting by following rays from the camera into the scene to find what each pixel actually sees and how light reaches it.Read more Path tracingPath tracing is ray tracing that follows light along many random bounce paths per pixel, converging on a physically accurate image as samples accumulate.Read more Fill rateFill rate is how many pixels or texels a GPU can write per second, setting a hard ceiling on performance at high resolutions and with heavy overdraw.Read more Shader throughputShader throughput is how much arithmetic a GPU's programmable cores complete per second, and it limits performance in shading-heavy modern rendering.Read more Frame timeFrame time is the milliseconds taken to produce one frame, and it describes smoothness far more accurately than an averaged frames-per-second figure.Read more

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