Question about the flatten loss about lasr HOT 4 CLOSED

Hi Xianghui, the flatten loss is borrowed from SoftRas. See the explanation here.

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Thank you so much for your explanation.

I have another question about the principal points prediction and processing part:

Also in your paper you said it is assumed the principle points are in the center of the image, why it is still needed here to predict the ppoints? Can we use zeros for this?

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why is it necessary to compute ppoints of the next frame from current frame?

We found using a constant principal points for a given frame pair (when computing the flow loss) produces better camera poses than predicting two separate pps. A reason is that separate pps are too flexible, which allows the change over pps to explain the majority of observed flow (instead of explaining by camera motion).

Also in your paper you said it is assumed the principle points are in the center of the image, why it is still needed here to predict the ppoints? Can we use zeros for this?

We could use a constant pp. But in practice that causes non-overlapping rendering issue in certain cases: see gengshan-y/viser#5

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I see, thank you so much for your quick response!

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