[GRASS-user] integration of sample.c algorithms into r.resample

[Maciej Sieczka]

Glynn Clements napisa?(a):
> Dylan Beaudette wrote:
> 
>> When I use your new version of r.bilinear method=nearest on a CELL image, the 
>> output is DCELL. While this can be fixed with r.mapcalc it shouldn't be too 
>> hard to add this to the new module (?) .
> 
> It's easy enough to change, although I'm not sure whether it's the
> right thing to do. It's arguable that the *only* difference between
> the methods should be the way in which the result is calculated. Out
> of the nine possible combinations of CELL/FCELL/DCELL input and
> nearest/bilinear/bicubic methods, at least 8 of them will produce a
> floating-point output map, so consistency would favour doing likewise
> for the one remaining combination.

> Whilst it would be possible to forcibly convert a CELL result to
> FCELL/DCELL with r.mapcalc in cases where that was required, it might
> not necessarily be obvious that a conversion is necessary until the
> first time you actually use method=nearest and end up having to figure
> out what happened.

Glynn,

That's right. But there is one situation when the output *will* be CELL
for sure - if the input is CELL and method=nearest. Maybe your resample
module could take that into account?

Other combinations are indeed hard to predict, as the most appropriate
output datatype will also depend on the combinations of output region
extent and input/output cell size and shape. So I guess defaulting to
DCELL is very good idea.

Maciek