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zorzi-s / PolyWorldPretrainedNetwork

PolyWorld: Polygonal Building Extraction with Graph Neural Networks in Satellite Images
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Question about Differentiable Polygon Rendering #18

Closed wanghr-git closed 2 years ago

wanghr-git commented 2 years ago

@zorzi-s Hello! Very pleased with your work，I don't quite understand the algorithm of one of the modules, the formula of the Differentiable Polygon Rendering algorithm you gave. How det(um,vm) is calculated specifically. Are u, v, m all two-dimensional vectors?

zorzi-s commented 2 years ago

Hello @wanghr-git! Yes, u,v, and m are two dimensional vectors. The matrix for the determinant is formed by stacking um and vm next to each other as column vectors.

wanghr-git commented 2 years ago

Thank you, I got it! In addition, I would like to ask you another question: in the process of calculating the wraparound number. Do pixel coordinates need to be converted to Cartesian coordinates?

zorzi-s commented 2 years ago

@wanghr-git Yes, we normalized pixel coordinates between -1 and 1 (where [-1, -1] is the top left corner of the image).

wanghr-git commented 2 years ago

Thank you!