Roughness areas and overlap (2009-07-10)

[Old Forum Archivist]

Hello,



I am doing digitalization of raster topography map.

I have one question, is it the good way if i have area which represent the water and area inside this that represent forest to draw first water, and inside this area to draw forest area, in this way two different roughness areas are overlapping?


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Remember that, for WAsP, there are not "areas" of roughness, but lines of roughness change. That's what the WAsP model 'sees', but they of course represent some real-world arrangement of different areas. It's possible to construct lines which will confuse the model by describing nonsensical arrangements of different areas. But what you ask about doesn't sound so problematic, if I understand your needs correctly.



If you draw some area of water, say a lake, then that's a closed polygon of roughness length change lines with the background roughness on the outside and the water roughness on the inside. You can draw an island on this lake with a smaller polygon of change lines with the water on the outside and the forest on the inside. WAsP will handle that perfectly well, and interpret it as a forested island on a lake. It doesn't matter which one you draw first. Is that what you mean?

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Yes,

I managed and created full roughness map for terrain of 10kmx10km, I found usefull information in help file in WAsP Map,



When I realized that WAsP sees LINES not Areas, everything suit well.



But, still thanks very much on your answer it confirmed my assumption.

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