Hi Martin, > I don't think that the difference between discrete and continuous coverage is > about returning null (nodata) values or not. I think that the difference is > rather that DiscreteCoverage do not applies interpolation. evaluate(point) > returns the same value for every point inside a pixel, no matter if the point > is > at the pixel center or near the corner of that pixel. On the contrary, > ContinuousCoverage can apply an interpolation, so that requerying the value at > the center or near the corner of a pixel will produce different values. > Whatever > that pixel represents a "nodata" value is an other topic.
My problem with this is that, to my mind, nearest-neighbour interpolation is still interpolation. You are still "inventing" data values where no data was measured. When I call evaluate() I need to know whether I am getting a "true" data value or an interpolated one. I am talking in particular about the case where a Coverage is created from a set of point measurements. One might decide that these points are representative of a finite-sized "cell" but there is no guarantee that these cells will be contiguous. Therefore in general there will always be points outside the cells that are unsampled. Are such points considered outside the domain of the Coverage? Or is a Coverage simply the wrong choice of data structure for this kind of information? Cheers, Jon -- -------------------------------------------------------------- Dr Jon Blower Tel: +44 118 378 5213 (direct line) Technical Director Tel: +44 118 378 8741 (ESSC) Reading e-Science Centre Fax: +44 118 378 6413 ESSC Email: [EMAIL PROTECTED] University of Reading 3 Earley Gate Reading RG6 6AL, UK -------------------------------------------------------------- ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Geotools-gt2-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
