Dear all,
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 ?
Thanks!
regards,
Ambrish
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