[GRASSLIST:2125] Re: New Location

[Paul Kelly]

On Fri, 2 Jan 2004, Markus Neteler wrote:

> Most unreferenced maps are imported with *negative* XY coordinates
> when using r.in.gdal. This behaviour should be discussed
> and probably changed. IMHO positive XY coordinates should be
> written except for AVHRR (as far as I remember, maybe also SAR).

Are both the X and Y co-ordinates negative? If so it doesn't seem to make
sense. It would make sense to me if only the Y co-ordinates were negative,
as then the absolute y co-ordinate of the centre of each pixel would be
the same as its row number (in the conventional way of numbering pixels in
image processing). This is maybe more familiar to people like me who
currently do most image processing in MATLAB.

But I don't really know how this works in practice and if it's hard to get
your head around while actually doing image processing in GRASS. If you
were just temporarily importing into the XY location before rectifying
then I don't see that the XY co-ordinate system would make much difference
at all.

Probably there is another disadvantage that I have missed?

Paul