Left / Right Decision When Exporting from Shape File

[Neil]

Hello,

I am just getting to know WASP and am trying to export a polygon shape file to the required format. I have read on the forum that there are other programs in which this can be done but ArcGIS is what we have and I have inherited a script to make the conversion which I need to debug.

My question is this : When I convert from polygons to lines should I do so for each polygon seperately (thus there will be duplicate lines for common edges) or use only one common edge? If the latter there will be situations where the decision "left or right" will be contradictory for common boundaries.

Thanks in advance,

Neil

[Ole Rathmann]

Hi Neil, it is still a problem to get from closed-polygon land-surface (roughness) representation to the "network" representation we use in WAsP. In the Help-system of the Map editor, in the topical page "Line types | Roughness lines | Roughness area topology" you will see the principle of the latter demonstrated. So, in you case, in stead of having to split up the polygons in smaller segmements fitted together at node-points it would be easier to keep the polygons but sqeeze them slightly, to make sure there is a small space of, say, 3 m, betwee adjecent polygons. Then neither the map editor nor WAsP itself would register any crossing line-segments not overlapping roughness areas.
Hope you may use this advice.

[Neil]

Hi,

Thanks for the reply. I am looking for a solution which is easy to automate so I was wondering if I couldn't instead use contour lines? If I convert the landcover to a raster and create contour lines that are for specific roughness class changes only, then two adjacent landcovers with ver different roughness classes will simply squeeze the intervening contour lines very close together.

I can then consistently set the Right as the higher value and left as the lower value either side of any given Roughness line?

Neil