I want to detect the grid in a image.

Given a image, I detected edges and fitted lines, then got error when using sdet_grid_finder::computer_homography().
" failed to find dominant groups with at least 60 deg orientation".

Does the function computer_homography() requires all lines are on grid? In my case the input image with complex background, I mean, there is chessboard in the image, but there are also some backgrounds in this image.

Anyone has experience using this class?