[GRASS-dev] Re: r.walk, r.cost & r.drain patches posted

[Colin Nielsen]

> Thanks for the updates. I'll give them a try. While I understand the reason
> for the gaps in the paths now, I think that it is important to find some way
> to get rid of them. That is, there needs to be some algorithm that will
> 'connect the dots' of knights move jumps.

I certainly agree but it should be done without adding cells in
between. The knight's moves should be retained in the output. We need
some kind of vectorization algorithm which connects cell center to
cell center, or which joins all the little line segments that would be
produced by a discontinuous path.

> Even without vectorizing, the cell accumulation
> values will be inaccurate if cells are skipped in a path from point A to
> point B.

The algorithm accounts for the accumulation value in these larger
jumps using pythagoras. Just as diagonals are multiplied by ~1.4,
knight's move jumps are multiplied by ~2.2 (but depending on the
resolution, etc.).

-Colin