● Problem o How to compute expected distance for any given(x, y, 8? Ray-tracing Cached expected distances for all(X, y, 8) o Approximation Assume a symmetric sensor model depending only on Ad: absolute difference between expected and measured ranges Compute expected distance only for(x, y) Much faster to compute this sensor model Only useful for highly-accurate range sensors ( e.g., laser range sensors, but not sonar)Problem | How to compute expected distance for any given (x, y, θ)? • Ray-tracing • Cached expected distances for all (x, y, θ). | Approximation: • Assume a symmetric sensor model depending only on ∆d: absolute difference between expected and measured ranges • Compute expected distance only for (x, y) • Much faster to compute this sensor model • Only useful for highly-accurate range sensors (e.g., laser range sensors, but not sonar)