ABSTRACT
This chapter examines laser ranging methods that focusing on the most commonly employed type of laser altimeter technology that uses pulsed laser light. The emergence of airborne laser swath mapping (ALSM) has provided a powerful means to characterize the elevation of the Earth's solid surface and its overlying covers of vegetation, water, ice and structures created by human activity. The bald Earth surface, or digital terrain model (DTM), is produced from those returns inferred to be from the ground based on spatial filtering that identifies lowest returns defining a continuous surface. Implications for the vertical accuracy of DTMs due to the upward bias of discrete-return, leading-edge ranging are apparent from histograms of elevation differences between ground control points and an ALSM ground topography DTM. ALSM is a uniquely capable method for collection of high resolution elevation data.
