Roughness map (shapefile)

[Pedro Quiroga]

Hi support team.

I'm working with a land-use map from Landsat which was converted to shapefile using Arcgis, this map was imported into the WAsP Map Editor, and then the attributes were specificated, my doubt is regarding the right and left-roughness, since shapefile only has one attribute of roughness per polygon (called gridcode), so my map has the same values for both roughness.

Could you give me an idea of how to assign each roughness?
Thanks for your help.

[Morten]

Hi Pedro,


I have no personal experience with this, but I believe that roughness values to the left and right side of each polygon or polyline in the SHP file should be stored in an a separate DBF file – with the same name and in the same folder, just using different filename extensions. You can read about this in the Map Editor help file section called ‘Map Formats> Vector maps> Shape files’. I am not sure exactly how you generate the DBF file with ArcGIS as I have never used this tool myself.


With best regards,
Morten Nielsen

[Pedro Quiroga]

Hi Morten,
Thanks for the prompt response, I was checking the help section and apparently there is a way to convert polygons to line, to get both roughnesses, the polygons option only has the internal roughness of each polygon, and as you mentioned is stored in a separate DBF file.
We are evaluating another option, we have a matrix with, X and Y coordinates and its respective roughness, we have a code in Matlab to create a .map file that writes the coordinates of a squared polygon for each roughness value in the matrix and as we know the roughness and location of each matrix element we can write as well the left side roughness, it is valid this approach (using a roughness polygon per element in the matrix)?
Thanks.
Best regards
Pedro

[Antonio]

Hi Pedro,

could you solve it, as we have the very same problem? We actually tried the following, that partially worked: we exported (via Global Mapper) the shape file as GRID (x,y,roughness) and imported it in Map Editor as a grid. Map Edito is able to create polygons from it. This was partially succesful, despite in this way there are a lot of problems of discretization, and the precess is very slow ... so we are still searching for the possibility to use the shape file directly.

thanks

Antonio

[Rogier]

I posted some instructions in the other thread about this topic.