Why do roads “disappear” from some scenes?
Aspect angle describes the relative orientation of the transmitted radar beam and the direction or alignment of linear features. It can have a significant influence on the appearance of radar imagery, especially when features in the scene have an organized linear structure, such as agricultural crops or geological structures. When a radar’s illumination is oriented perpendicular to geologic features such as faults, lineaments and outcrops, increased contrast and shadowing of the features in the image results. This is a favourable aspect angle for the image interpreter, as terrain is enhanced. In agricultural applications, fields imaged from different aspect angles may result in different tones on the image because of row or planting direction. Aspect angle can cause imaging geometry to be either enhanced or suppressed.
