Whoever produced the DEM should have provided a contour equivalency. The appropriate contour interval is very dependent on the type of the topography in the area as well as the quality of the equipment gathering the data and the post processing.
The DEM was produced from stereo imagery. I have the post spacing and point density images, but I still can't find any literature that addresses this problem. I would like to find something that says the relationship between DEM's and contours is based on more than a hunch.
