Simple Case
If we know the 3D position of the points and know they are on an ellipsoid Q, we could directly use the equation: $X^TQX=0$, where Q is the 4x4 matrix.
Question
I'm wondering is it possible to build a constraint only use the information on image planes. If we know the projected points coordinates $[u_1, u_2, ...]$ of points $[X_1, X_2, ...]$, is there an equation that: $f(u_1, u_2, ...) = y(Q, P)$, where P is the projection Matrix.
Maybe we could use the distance between two points, crossratios between several distances and so on?
Thank you so much.