ambijat wrote: > I have a typical problem. I have extracted the raster > boundary line from SRTM data. each cell contains the > elevation value. Idealll\y speaking the total length of a > boundary would be the some of the cells x cell resolution > (90m). But, this is not true to actual boundary length as > there are elevation in mountainous regions. > > So, I need to add all the hypotenuse values of the cells. > How can it be done any idea ?
you can do lots of refinement, but fundamentally it's a fractal problem with no real answer, see http://en.wikipedia.org/wiki/How_Long_Is_the_Coast_of_Britain%3F_Statistical_Self-Similarity_and_Fractional_Dimension the 2D plan-area within a boundary will converge on a single answer though as you make dx smaller and smaller. also within a single constant dataset you can compare one area to another ("this edge is x% of the total boundary"). v.to.rast + v.to.db may give you an answer, but I won't use it. see also the r.surf.area and r.volume modules, which are slightly different creatures in the same family of problem. Hamish _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
