Professor Guth Viewshed Research
Computing intervisibility with line-of-sight profiles and viewsheds represents one of the important uses for digital topography, with applications for the military, communications engineers, landscape planners, and others. The computations must consider data resolution, quality, and format, and have generally used a single surface and neglected the effects of vegetation. Vegetation can potentially be included in a number of ways. (1) Separate grids from LIDAR or IFSAR contain the bare earth elevation (or bare earth and buildings) and the first return, and the difference between these provides the vegetation height. (2) Vector data sets contain vegetation information, which can be combined with the topography grids during analysis, probably most easily with a vector to grid conversion. (3) Gridded land cover data sets include vegetation categories, some of which include tree height data. Examples of these include NLCD, NBCD 2000, and LandFire. Most of these approaches will require probabilistic models with ranges of heights assigned to the vegetation categories based on analysis of local conditions, but with suitable development of algorithms will greatly improve on current intervisibility computations. Regardless of the approach, viewshed results should be compared to recent high resolution imagery to verify that vegetation reported in digital data sets still represents reality. Commercial tree farms and orchards grow rapidly and can significantly impact intervisibility in many areas.
Peer reviewed papers
Published Conference Proceedings
last revision 3/29/2016