Question regarding equation for calculating J

[graphdeco-inria]

Question regarding equation for calculating J

[yklcs]

I believe the corresponding equation in the Ewa Splatting paper (not Ewa Volume Splatting) is equation 34 instead of 29. Equation 29 is for volume splatting while 34 is for surface splatting.

[fzhiheng]

Hi everyone! Thanks for the wonderful work and for releasing it!

I had a problem reading the paper and looking at the code. On the paper "EWA volume splatting" on equation (29), how to compute the J would be like this:

However, on the code (cuda_rastizer/forward.cu), its implemented like this: Which is different from the paper. I understood why you are multiplying by the focal lenght bu I did not understand the row of zeros. Also, since there is a row of zeros, this matrix is not invertible, which would mean that cov is not invertible, which would mean it is not a valid covariance matrix, which, I imagined would cause some problems.

Is there anything I missed? Why did the authors implement the code in this manner?

Thanks for the help!!

Hi, I did not understand why we need to multiply by the focal lenght. Looking forward to your help.