Question about the opacity along the ray

[nnop]

Hi, Zehao,
Thanks for the brilliant work. I have a question about the opacity along the ray.
Why does the opacity being maximum in the middle and not continuously accumulated in the right half area?

[niujinshuchong]

Hi, this is related to how Gaussians are rendered. It can be thought that the Gaussians are modeling the accumulated opacity (weights) already, as otherwise we need to integrate it when rendering. Therefore we don't need to accumulate it. And as the accumulated opacity is monotonous increasing, we maintain the maximum value after the ray passes the peak of Gaussian.