ABSTRACT
The concepts in engineering, hydrology, geology, geomorphology such as absolute and relative heights, degrees of slope, areas, volumes, slope and height frequency distributions, isotangent and isosinal slope maps, are derived from the measurement of horizontal lengths in the plane of the map. This chapter develops that the formulae give the opportunity to estimate the contribution of the variances of the conventional modes of measurement and plotting, to the variance of a contourline in a map. The plotting of contour lines at a large and medium scale by computer interpolation as well as the method of sampling heights per unit of area, giving ultimately a good impression of form lines. The influence of the precision of the map is small in respect of the influence of the photogrammetric procedures; the influence of, being dependent on N, is largest if N is maximum, usually in rough topography.
