@techreport{Parberry2014TR4,
  author = {Ian Parberry},
  title = {Tobler's First Law of Geography, Self Similarity,
and Perlin Noise: A Large Scale Analysis of Gradient
Distribution in Southern Utah with
Application to Procedural Terrain Generation},
  institution = {Laboratory for Recreational Computing, Dept. of Computer Science \& Engineering,
                 Univ.\ of North Texas},
  number = {LARC--2014--04},
  year = {2014},
  month={June},
 }