1. A range determiner assembly comprising: an image sensor configured to obtain image data for each of three views of a target at each of a plurality of different locations along the track of a craft moving at a determinable altitude above a surface of the earth; a detector board comprising a first line array, a second line array and a third line array, each of the first, second and third line arrays receiving a respective sequence of images from a corresponding one of the three views; and processing circuitry configured to determine a relative distance between the craft and the target based on the image data.