Hello,

For a DEM, I would like to calculate the surface angle (i.e. slope) for each grid cell in the 4 cardinal directions (N, S, E and W). In other words, for a given cell, what is the angle between a flat plane and the DEM surface in each direction.

For example, a grid cell located on a 45 degree slope facing due west (270 degrees aspect) would have angles relative to a flat plane of 0, 0, 45 and -45 (or 225) degrees for N, S, E and W respectively.

Does anyone know how this can be generated using Arc? I imagine it would require generating 4 separate grids, one for each direction.

For a DEM, I would like to calculate the surface angle (i.e. slope) for each grid cell in the 4 cardinal directions (N, S, E and W). In other words, for a given cell, what is the angle between a flat plane and the DEM surface in each direction.

For example, a grid cell located on a 45 degree slope facing due west (270 degrees aspect) would have angles relative to a flat plane of 0, 0, 45 and -45 (or 225) degrees for N, S, E and W respectively.

Does anyone know how this can be generated using Arc? I imagine it would require generating 4 separate grids, one for each direction.

In Spatial Analyst hydrology the flow direction command gives you a number representing one of the 8 directions (N, NE, E, SE, S, SW, W, NW) that is unique to the four corners. This is slope is towards the lowest of the of the surrounding cells and may not be the same as aspect.

Hillshade produces a value based on horizontal direction, but I'm sure if it can be correlated to cardinal directions.

Just some ideas...