●。● Computing Importance Weights (Approximate Method) o Off-line for each empty grid-cell(x, y) Compute d(x, y the distance to nearest filled cell from(x, y) Store this"expected distance"map o At run-time, for a particle( x, y) and observation z=(r, 8) Compute end-point (x,y)= X+rcos(0), y+rsin (e)) Retrieve d(x, y and compute Ad from △d=r-d(x,y) Compute p( Ad x) from Gaussian sensor model of specITIc oComputing Importance Weights (Approximate Method) | Off-line, for each empty grid-cell (x, y) • Compute d(x, y) the distance to nearest filled cell from (x, y) • Store this “expected distance” map | At run-time, for a particle (x, y) and i observation z =(r, θ) • Compute end-point (x’, y’) = (x+rcos(θ),y+rsin(θ)) • Retrieve d(x’, y’) and compute ∆d from ∆d = r - d(x’, y’) • Compute p(∆d |x) from Gaussian sensor model of specific σ2