How can I read and extrapolate a grid from an image?

edit

I'm a complete noob to OpenCV and just need nudge in the right direction. I'd like to project a grid on an object, then process an image of that object with the grid on it. I'd then like to see if I can determine the 3D shape of the object from the grid deformation. I assume this breaks down into 2 overall tasks:

-read the grid from the image and determine the vector or geometric data of the grid.
-process that data to determine the 3D shape.

How would I do this? Are there specific libraries/examples I should be looking at to get started on each of these tasks? Thanks.