Hi everyone,

Here is a stupid question about the estimation of trifocal tensor. I think this mail list should be the right place to get the help.

I am writing a program to estimate the trifocal tensor using the linear method mainly with ppp and lll configurations. I know this process consists of three steps: normalizing features, solving a linear system of equations and recover the original tritensor. I am sure the first two steps are OK as I have test the result using mvl functions such as TriTensor::image1_transfer(). But I've got some problems to recover the trifocal tensor.

I use the equation (9.2) of Faugeras and Luong's book(Geometry of Multiple Images, 2001) but can't get the right result. So my questions are:
(1) If the transformations H,H',H'' in (9.2) are the same to those used to normalize the image features? My idea is no. As I normalize the line segments by normalizing its two endpoints, the two transformations for points and line segments should be identical in one image. But they are transformations for points, not lines.
(2) If the equation (9.2) is correct as I am a little suspicious of its veracity.
(3) Please give me a short algorithm to recover the tritensor, i.e. the third step.

Any help appreciated!

Leonard