Spatial View - Slope grid and Slope Angle grid

[HPJ]

Hi,

I was wondering how the slope grids are calculated in WEng? I can understand how the terrain inclination grid is done, but the slope grids I can't figure out.

Thanks!

- Hans Peter

[Duncan]

Hi Hans Peter,

In different versions of WEng, it's been done slightly differently.

In WEng 3, the slope angles are coming from the LINCOM flow model analysis somehow. I'll ask my colleague Qiangbing to add a bit more detail describing what happens.

At some point in the past we were using a separate algorithm which used some spline fitting on the elevation surface, but I'm not sure which versions of WEng actually applied that.

HTH, Duncan.

[Qiangbing]

Hi,
The slope gird is calculated straightforwardly from the terrain inclination grid.
For terrain inclination (dx, dy) the slope in percentage is s = sqrt(dx^2 + dy^2), which is the length of the inclination vector, while the aspect is just the direction of the vector, a = atan(dy/dx).

Qiangbing