upslope/downslope along a line

[ToreBorvik]

Hi.

I'm making a model that analyses least cost path From A to B and back from B to A. it outputs a polyline

This line represents a proposed road.

My model has come this far..

Problem: Maximum allowed slope is lesser uphill than downhill, so I need to find a way to add this to the model.


Example: When driving from startpoint A in the west to midpoint B in the east, the road back will likely not be the same as to, since now we drive in the opposite direction and reverse downhill/uphill.


I hope you understand. And I also hope someone has a tip on how to solve it!


Running ArcInfo 9.3.1. with all extensions

[ToreBorvik]

Thanks for the suggestion. I've tested a bit with path distance but I do not quite know how to get this information from it (I got an output but it makes no sense).

The purpose of my entire model is to add a start point and a stop point and find the quickest way between these while avoiding certain areas (which works fine), but it must also regard the upslope/downslope along the suggested line since the max allowed slope is different between these two.

So the path distance is what I lack. for possible inputs I have pregenerated: DTM raster, slope raster, aspect raster, cost distance raster, cost path line.

And the settings: max 25 degrees downslope  and max 15 degrees upslope.

Can I make the calculation based on what I have? if no, what do I need also? and where do these inputs go into the tool?

[ToreBorvik]

ahhh. Never mind this whole post. I thought initially that the path distance should be combined with the cost distance. but after trying I see that it can replace the cost distance so that the path distance raster can be input for cost path.

But right now I have two path distance calculations in my model since to my understanding I needed it to calculate both one for FROM A TO B and another one for FROM B TO A.


attached a screen of the model output, seems to work great and I also manually checked it with an aspect and slope raster, does its job 🙂

Blue Line = A to B with certain high cut/low cut angles.
Green Line = B to A with different angles

I could set the angles to be the same and still get different results, but I realized that now I can also model slope restrictions if a forestry truck is either loaded with timber (usually from a to b) or not (b to a). an extra bonus, hooray!