[GRASS-dev] Nearest neighbour

GRASS GRASS developer
1

I noted that both r.proj/r.proj.seg use floor() in the NN method
(at least in 6.4). Should not be a proper rounding to the nearest integer
more appropriate?

--
Francesco P. Lovergine

2

Hi Francesco,

I noted that both r.proj/r.proj.seg use floor() in the NN method
(at least in 6.4). Should not be a proper rounding to the nearest integer
more appropriate?

glad you raise the question. I found the same methodology in the java
NN methods and was right these days I was wondering. The docs say it
is due to performance issues. Not sure if it is the same here.

Very interested here,
Regards,
Andrea

--
Francesco P. Lovergine
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3

Francesco P. Lovergine wrote:

I noted that both r.proj/r.proj.seg use floor() in the NN method
(at least in 6.4). Should not be a proper rounding to the nearest integer
more appropriate?

No.

If a projected point has grid coordinates (2.99, 3.99), the cell with
indices (2,3) contains that point, and its centre is the closest to
that point.

If the value of cell represents a sample taken at a point, the sample
point is the cell's centre, not its top-left corner.

--
Glynn Clements <glynn@gclements.plus.com>