Note: This page has very little or no relation to aviation, but was created for the purpose of understanding a different topic better.
The Moiré effect was a visual effect previously used in beacons along shorelines to indicate underwater hazards.
A Moire effect is what happens as a result of moiré patterns, patterns you appear to see when two similar but slightly different patterns are overlayed on each other.
These beacons that utilized the moiré effect were called a leading mark indicator and patented in 1986 (Patent Number 4,629,325 Link Here) and the patent was assigned to a company called Inogon. (Full Patent At The Bottom) This light was now called a Inogon leading mark.
The U.S. Coast Guard analyzed the concept and installed it somewhere near New York harbor and was later concluded that it could be used to guide aircraft to properly park in their gates.
Credits: This article was based on the research done for the A-VDGS article, specifically the APIS system by FMT. Information from this article was pulled from the Wikipedia article regarding the Moire pattern (Link), the Google Patent page for the United States patent of the leading mark indicator (Link) and finally, the United States Coast Guard Research and Development Center analysis and evaluation of the Inogon Leading Mark (Link).