Computer system and method for maritime surveillance and satellite-based earth observation of objects using nadir-oblique image matching

A method of computer vision-based maritime surveillance and identification of unknown vessels, the method comprising:

• comparing, via a neural network, a cropped nadir image to at least one oblique image of a known vessel stored in an oblique imagery database, the comparing including determining a similarity score indicating a similarity level between the cropped nadir image and the compared oblique image, the oblique image containing a known candidate vessel having a known unique vessel identifier associated therewith that is stored in association with the oblique image and which identifies the known candidate vessel;
• outputting, via the neural network, a ranked list of the oblique images that were compared to the cropped nadir image, the ranked list based on the determined similarity scores, wherein a higher ranking in the ranked list indicates a higher similarity score and greater likelihood of the known vessel in the oblique image being the same as the unknown vessel in the nadir image;
• and
• assigning at least one unique vessel identifier to the cropped nadir image based on the ranked list.

A method of training a nadir-oblique image matcher model for computer vision-based object tracking, the method comprising:

• pretraining an oblique image encoder branch for use in a nadir-oblique image matcher model, the oblique image matcher encoder branch trained in oblique-oblique image matching;
• pretraining a nadir image encoder branch for use in the nadir-oblique image matcher model, the nadir image encoder branch trained in nadir-nadir image matching;
• and
• training the nadir-oblique image matcher model using the nadir-nadir pretrained model and the oblique-oblique pretrained model, using pretrained weights obtained from pretraining the oblique image encoder branch and pretraining the nadir image encoder branch in the nadir-oblique image matcher model;
• wherein the nadir-oblique image matcher model includes separate oblique and nadir image encoder branches.