@article{Caldwell_2001, title={Physical Terrain Modeling for Geographic Visualization}, url={https://cartographicperspectives.org/index.php/journal/article/view/cp38-caldwell}, DOI={10.14714/CP38.795}, number={38}, journal={Cartographic Perspectives}, author={Caldwell, Douglas R.}, year={2001}, month={Mar.}, pages={66–72} }