Generating contour lines using different elevation data file formats
  In terrain mapping, there are so many ways to measure and estimate the terrain measurements like contouring, vertical profiling, hill shading, hypsometric tinting, perspective view, etc. Here in this paper we are using the contouring techniques to generate the contours for the different digital elevation data like DEM, HGT, IMG etc. The elevation data is captured in dem, hgt and img formats of the same projected area and the contour is generated using the existing techniques and applications. The exact differences, errors of elevation (contour) intervals, slopes and heights are analyzed and recovered. 
P. S. Hiremath, B. G. Kodge
cs.OH