r.random.cells not working correctly when min distance is < 0.1

[pvanbosgeo]

I am running r.random.cells in location/mapset with latlon with a resolution of 0.008333. When using a minimum distance of e.g., 0.09 degrees, random locations / cells are selected that are closer then that distance, including selection of neighboring cells.

[hamish]

what is your ew, ns region resolution? (the module uses that)

r.random.cells does not know that 1deg lat is not the same distance as 1deg lon. Considering the nature of what it is doing (feeding into future stats) I wouldn't risk the wrong answers, I'd run it from a projected location instead of a lat/lon one.

the module is smart enough to deal with ew,ns resolution (of the same units) being different though.

Hamish

[pvanbosgeo]

random points generated with r.random.cell with minimum distance of 0.09 degrees. Regions resolution is 0.00833.

[pvanbosgeo]

The region's resolution is 0.008333. Good point about different distances latitudinal and longitudinal. In my specific case it doesn't really matter though, I just want to avoid to select any two cells that are e.g., less then 2 cells apart). A minimum distance of 0.09 should take care of that, shouldn't it. However, the resulting layer does still contain plenty of neighboring cells selected (see attached image).

[hamish]

without exploring the code to closely, perhaps what is happening is that the random points in real x,y,z space are more than 1 cell space apart from each other, but at the final rasterization step they trigger filling adjacent cells?

+------+
|   .  |
|      |
|      |
+------+
|      |
|      |
| .    |
+------+

But r.random.cells works on distance between the rows and columns, so perhaps that is wrong and it is comparing distance between cell centers. Further investigation would be needed to see at what stage the rasterization happens.

Hamish

[martinl]

What is status of this issue?