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zhengthomastang / 2018AICity_TeamUW

The winning method in Track 1 and Track 3 at the 2nd AI City Challenge Workshop in CVPR 2018 - Official Implementation
http://openaccess.thecvf.com/content_cvpr_2018_workshops/w3/html/Tang_Single-Camera_and_Inter-Camera_CVPR_2018_paper.html
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Step 2- Camera calibration old method vs new method #25

Open bitasd opened 3 years ago

bitasd commented 3 years ago

Hi, Thank you so much for providing us with your codes. I am a bit confused about the output of step 2, the old method, which produces a Projection Matrix (3 x4) and the newer version which produces a Homography Matrix (3x3). Since the projection matrix is fed into the code in the speed estimation step, I was wondering how the homography matrix could be converted into the projection matrix.

I really appreciate your response, Bita

zhengthomastang commented 3 years ago

Hi Bita. The homography matrix cannot be converted into a projection matrix, but a projection matrix can be converted into a homography matrix. Since the homography is just a transformation from one plane to the other plane (ground plane to image plane), this is all you need for estimating the speed if the ground plane is flat (approximately). But you may need to modify the code of speed estimation to change the projection part.