Methods and systems for image alignment of at least one image to a model

A method for image alignment of at least one two-dimensional or three-dimensional image to a two-dimensional or three-dimensional model, executed on a processing unit, the image alignment having an acceptable likelihood of mismatch between the at least one image and the model, the method comprising:

• selecting a value for a radius in Fourier space;
• discretizing a set of poses into a discrete grid of candidate poses and a set of shifts into a discrete grid of candidate shifts;
• determining a fixed fraction as an upper bound on the acceptable likelihood of mismatch, the fixed fraction being determined based on, at least, the fraction of poses and shifts that are discarded on typical dataset of images;
• the processing unit iteratively determining whether a selected accuracy of image alignment has been obtained, and when such determination is false:
• assigning a lower bound to the acceptable likelihood of mismatch, the lower bound comprising a first component;
• analyzing the image to isolate selected portions of the image that are below the value for a radius in Fourier space;
• determining values for the first component for each of the poses and shifts on the discrete grid of candidate poses and the discrete grid of shifts, using only the isolated selected portions of the image;
• determining a reference first component using a value for the fixed fraction;
• parsing the discrete grid of candidate poses by analyzing each one of the candidate poses over all of the candidate shifts to obtain a minimum value of the first component over all the candidate shifts and discarding each candidate pose from the discrete grid if the first component exceeds the reference first component;
• parsing the discrete grid of candidate shifts by analyzing each of the candidate shifts over all of the candidate poses to obtain a minimum value of the first component over all candidate poses and discarding each candidate shift from the discrete grid if the first component exceeds the reference first component;
• for every remaining pose in the discrete grid of candidate poses, replacing the pose with a plurality of subdivided grid points representing the candidate poses;
• for every remaining shift in the discrete grid of candidate shifts, replacing the shift with a plurality of subdivided grid points representing the candidate shifts;
• and
• increasing the radius in the Fourier space;
• and
• otherwise, returning the pose and shift at the lower bound with minimum value.