When several images are orthorectified, we are often asked to generate a mosaic of the combined scenes. Mosaics help simplify the end result by eliminating the need to track each output scene individually. The output from a combination of orthorectification and mosaicking is often referred to as an orthomosaic.
During the mosaic process, each image is added to the mosaic individually by an analyst. The analyst chooses a cutline (the edge between the new scene and the mosaic) carefully so that the line between the two will not be visible. A good cutline will follow natural edges such as roads or fields so as to mask the difference between images. It will also avoid clouds, shadows, and other undesirable portions of each input scene. Many imagery companies run their orthos through an auto-cutline generator to save time and money, but this often results in mosaics where cutlines are at least partially visible. While we have the ability to use an auto-cutline generator, our standard procedure calls for a human to draw cutlines, resulting in a superior product.
Color-balancing of mosaics is also best achieved by a human and not a computer. Although we offer the option of no balancing or computer balancing for budget consumers, our standard mosaic protocol calls for manual color balancing of each scene that is added to the mosaic. This ensures that the seam between images is virtually invisible, or “seamless.” For jobs with large numbers of images, manual color balancing is assisted by color ramping, our proprietary differential superposition method, and other advanced techniques across the extent of the project area. Whether the project involves 2 scenes or 200 scenes, our experienced image analysts are able to produce consistently-balanced, evenly-toned, seamless mosaics. We pride ourselves in the quality of our orthomosaics, which are used globally for base mapping, scientific analysis and even artistic