[R-sig-Geo] stars st_transform gives NA to the offset and delta parameters

[Edzer Pebesma]

On 07/06/2021 01:16, Manuel Spínola wrote:
> Dear list members,
> 
> When using st_transform in a stars object the offset and delta parameters
> become NA, is this an expected behavior?

Yes, it also says that you got a curvilinear grid as a result, which is 
a grid with non-constant cell size (delta) and non-constant coordinate 
of the side (offset); see 
https://keen-swartz-3146c4.netlify.app/intro.html#raster-types

If you want a regular grid in the new CRS, use st_warp(), preferably 
with the target grid template.

> 
> 
> geomatrix = system.file("tif/geomatrix.tif", package = "stars")
> x = read_stars(geomatrix)
> 
> new = st_crs(4326)
> y = st_transform(x, new)
> y
> 
> 
> 
> 
> *Manuel Spínola, Ph.D.*
> Instituto Internacional en Conservación y Manejo de Vida Silvestre
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-- 
Edzer Pebesma
Institute for Geoinformatics
Heisenbergstrasse 2, 48151 Muenster, Germany
Phone: +49 251 8333081