Determination of Building Model Key Points Using Multidirectional Shaded Relief Images Generated from Airborne LiDAR Data

Algorithm 1

Improvement of mask in marker-controlled watershed.

Pgrad← Modified slope by proposed method

R, C← Size of Mgrad (Modified slope)

, ← Thresholds

Mwin← Moving window

minV ← Minimum value of Mgrad

Pgrad = Mgrad

Pgrad (Mgrad < ) = minV

for y = 2 to R - 1

for x = 2 to C - 1

Mwin = Mgrad (n x n window at (x, y))

if (standard deviation of Mwin) <

Pgrad (n x n window at (x, y)) = minV

end

end

end