Onboard geolocation for images

A method for on-board spacecraft image geolocation, the method comprising:

• sensing timestamped images with an image sensor of a spacecraft;
• collecting orbit position data using one or more sensors of the spacecraft;
• collecting attitude data using one or more sensors of the spacecraft;
• generating, by one or more electronic circuits onboard the spacecraft, timestamped ephemeris data for the spacecraft based on the orbit position data;
• generating, by the one or more electronic circuits onboard the spacecraft, using a Kalman filter, timestamped attitude data for the spacecraft based on the collected attitude data;
• projecting, by the one or more electronic circuits onboard the spacecraft, a pixel ray from the image sensor to a point on the Earth, based on the timestamped attitude data and the timestamped ephemeris data, the pixel ray specific to a target pixel(s) of a target element in at least one of the timestamped images;
• determining, by the one or more electronic circuits onboard the spacecraft, an intersection between the pixel ray and a digital elevation model;
• determining, by the one or more electronic circuits onboard the spacecraft, in real-time, timestamped geolocation data for the target pixel(s) in the at least one timestamped image, based on the intersection;
• refining, by the one or more electronic circuits onboard the spacecraft, the geolocation data for the target pixel(s) in the at least one timestamped image, based on correspondence between the at least one timestamped image and a three-dimensional digital construct of at least a portion of the Earth;
• correcting, by the one or more electronic circuits onboard the spacecraft, attitude filter parameters of the Kalman filter, based on the refined geolocation data for the target pixel(s) in the at least one timestamped image;
• generating, by the one or more electronic circuits onboard the spacecraft, using the Kalman filter with the corrected attitude filter parameters, additional timestamped attitude data for the spacecraft based on the collected attitude data;
• and
• determining, by the one or more electronic circuits onboard the spacecraft, additional timestamped geolocation data for ones of the target pixel(s) based on the additional timestamped attitude data.