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Good morning,

I would like to have precision on ZONALCENTROID of the GRID module.

I study watersheds’ geometry using a DEM and a coverage of outlets.

In the GRID module, I have extracted the basins for each outlet with
WATERSHED, to have one grid for each basin.
Then, I have used ZONALCENTROID to obtain a new grid defining the
equivalent ellipse for each basin, its centroid and its axis.
For many basins, I have got an error message, because the new grid had
nodata everywhere, so could not be defined.

One amazing thing is that when I use the ZONALGEOMETRY with the ellipse
option, I get a statistical table with erroneous ellipse parameters, but
no error message.

To solve the problem with ZONALCENTROID, I have tried :
- to round a little the limits of the basin, with a FOCALMAX and then,
- to reduce the study area using a boundary obtained from the polygon
coverage of the same basin (determined by GRIDPOLY).

And, for some basins, it seems to work well. But, not for every basin.

I would be delighted if anybody could help me to solve this problem.
Thank you.

Best regards,

Julie Charleux