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John Caron wrote:
Martin Daly wrote:My interoperability concern is more for the case when the extents don't go outside to [0,180] and [0,90] range. How can a client know whether this is right or left of the prime meridian, or above or below the Equator? we always assume + means north, east, and - means south, westSorry, I didn't explain myself very well. What I meant was, if the full extents of the coverage are in the range [0,180] and [0,90], then the client has no way of knowing what the origin is. That is, the client could detect longitudes > 180 and latitudes > 90 and deduce that the server is using the [0,360] and [0,180] ranges. But that hueristic breaks down for smaller extents. Like I said, the extents ranges should probably respect the CRS extents and origin. That way there is no guesswork involved. Just trusting the results might not be enough. For example, our client allows the user to clip the coverage request to the extents of the current view. We need the current view extents and the coverage extents to either be in the same domain, or to be able to know the domains. Regards,MartinThis reminds me of a question Ive been meaning to ask.Suppose the client asks for an area that is bigger than the actual data area. I assume that we should return the intersection?What if the client asks for an area that doesnt intersect? Is that an illegal request? Do we return an empty file?
my spontaneous reaction: both is an error. The spatial extent is advertised, and the client must keep with that. Otherwise we more and more deviate from the correlation between what is being asked and what is being returned. I don't feel happy with an empty file - if this indicates a nonregular situation, it should be flagged as such = an error code should be returned. Otherwise the client, in particular a non-leight-weight one, may run into dozens of case distinctions before being able to really process what's been received. My personal opinion is that this would take away some elegance and clarity from WCS.
I know that WMS also allows a "far zoom out", which may be nice for viewing (well...some people may think so), but again: the primary mission of WCS IMHO is to serve _original_ data.
just my 2 cents... -Peter -- Dr. Peter Baumann - Professor of Computer Science, International University Bremen www.faculty.iu-bremen.de/pbaumann, mail: p.baumann@xxxxxxxxxxxx tel: +49-421-200-3178, fax: +49-421-200-49-3178 - Executive Director, rasdaman GmbH www.rasdaman.com, mail: baumann@xxxxxxxxxxxx tel: +49-89-67000146, fax: -67000147, mobile: +49-173-5837882 "A brilliant idea is a job halfdone."
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