As discussed in the forums, specification of the ROI should be done in world coordinates rather than component coordinates - the documentation should reflect this, perhaps using the .. warning directive to reflect that this is a temporary state of affairs...
I also note that if your ROI is at worldZ=0, VRT does not work, but if it is at 1 mm (or I assume any non zero value) then it does work...
As discussed in the forums, specification of the ROI should be done in world coordinates rather than component coordinates - the documentation should reflect this, perhaps using the .. warning directive to reflect that this is a temporary state of affairs...
I also note that if your ROI is at worldZ=0, VRT does not work, but if it is at 1 mm (or I assume any non zero value) then it does work...