Before revision: Visual clues When a non-moving background (typically the shore line) is present, CBDR situations can be recognized by the fact that some part of the moving target vessel is not visually moving against the background.
After revision: but not alwaysVisual clues When a non-moving background (typically the shore line) is present, CBDR situations can be recognized by the fact that some part of the moving target vessel is not visually moving against the background.