Lighting invariant matching algorithm (lima)

An aerial vehicle comprising:

• (a) a computer having a memory;
• (b) a processor executing on the computer;
• (c) the memory storing a set of instructions, wherein the set of instructions, when executed by the processor cause the processor to perform operations for illumination invariant image mapping for terrain relative navigation (TRN) of the aerial vehicle, the operations comprising:
• (1) obtaining a first image of a terrain segment having a known first sun vector, wherein the first image is obtained in a first lighting condition;
• (2) obtaining a second image of the terrain segment having a known second sun vector, wherein the second image is obtained in a second lighting condition that is different than the first lighting condition;
• (3) registering the first image to the second image, wherein the first image and the second image are matched;
• (4) obtaining a target third image of the terrain segment having a known third sun vector, wherein:
• (i) the target third image is obtained in a third lighting condition;
• (ii) the third lighting condition exceeds a threshold required for matching;
• (5) synthesizing a synthetic composite image based on (a) the first image and the second image, and (b) the first sun vector, the second sun vector, and the third sun vector, wherein:
• (i) the synthetic composite image is registered to the first image and the second image;
• (6) matching the synthetic composite image to the target third image;
• and
• (7) based on the matching, deriving and using a TRN solution to navigate the aerial vehicle.