[EMAIL PROTECTED] wrote on 03/01/2007 01:14:34 AM:
> From a geotools-users thread: > > I've seen this in world images as well. I do believe the correct > > behavior would be not to assume anything, and return a null CRS. > > That's what vector datastore do, so it would be consistent. > > (it may be my fault if in origin they did return WGS84... well, > > I guess I was wrong :-) ) > > > Simone ha scritto: > > Ciao Andrea, > > actually I was thinking that when we change this, since I agree that we > > need to change this, we should defaul to ImageCRS because it could the > > case of having an image without CRS or an image which is no georectified > > but only geolocated by a certain numbers of Ground Control Points or the > > like. This might be non-consistent with Feature but > > that's hwo people expect things to be hande, IMHO at least :-). > > Hmmm... it makes sense, but I like consistency. Following this approach, > on the vector side we would have to use DefaultEngineeringCRS instead of > null. The authoritative response from ISO 19123 is that data without a known CRS have an EngineeringCRS. Be careful with the word "Image" (and ImageCRS). A DEM is not an Image even though it is gridded. Pictures are images. Rendered maps are images. Gridded data are coverages. "Georectified" means that there is an affine transform between the grid axes and your CRS. The grid cells are also all the same size. "Georeferenceable" means that there is a defined transform between grid cell location and "location-in-a-geospatial-CRS", but this relationship may have an unbounded complexity. Higher order warping functions, mathematical models of sensor optics and platform attitude, etc. are all examples of "Georeferenceable". ISO is just figuring out how to handle sensor data and has given up on trying to meaningfully define an "Image" as something distinct from plain old gridded data (for the moment). I would suggest that we treat all gridded sources as if they were gridded data until a clearly defined "Image" concept is generated. Bryce ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Geotools-devel mailing list Geotools-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-devel
