Tracing the Edge

CUGOS Fall Fling 2013

Tools

Code:

Canny Filter

noise reduction

intensity gradient

horizontal and vertical derivatives

thresholding

non-maximum suppression

337.5<theta<22.5 & 157.5<theta<202.5

22.5<theta<67.5 & 202.5<theta<247.5

67.5<theta<112.5 & 247.5<292.5

112.5<theta<157.5 & 292.5<theta<337.5

hysterisis

how the weak become strong

Geographic Features

scale

    groundResolution = (math.cos(latitude*math.pi/180)*2*math.pi*r_earth)/
                       (256*math.pow(2,level))

    mapScale = (groundResolution*dpi)/0.0254

angle variance

length

Results

Canny

Modified Curved

canny = Canny(low=10,high=30,length=5,angle=180,lat=47.653941,zoom=19)

Straight

canny = Canny(low=10,high=30,length=2,angle=2,lat=47.653941,zoom=19)