ACSCull: visibility-aware triangle elimination for skinned characters under an admissible Camera Set

Top-down mobile games render skinned characters under a tightly bounded cinematic envelope yet ship meshes authored as if every face could be observed from any direction. Triangles outside that envelope are rasterised every frame at no visual benefit. We describe ACSCull, an offline pre-pass that removes such triangles for pre-composed skinned characters. The method formalises the game's cinematic envelope as an Admissible Camera Set (ACS) - a five-tuple of pitch, yaw, distance, field of view, and aspect - and identifies the visibility set by rendering K cameras × P poses sampled from a low-discrepancy sequence over the ACS into an R32UI render target with per-triangle identifiers carried as flat-interpolated vertex attributes. Non-visible triangles are eliminated and the geometry is re-emitted as standard glTF Binary, drop-in compatible with mobile NDK and WebGL runtimes. Removes 27-55% of triangles from skinned characters by visibility; composable with conventional mesh simplifiers. Output is standard glTF Binary; runtime renderer requires no changes. Held-out SSIM ≥ 0.9999 in-ACS and ≥ 0.9997 under ±5° pitch / ±25% distance perturbation.