On Monday 11 August 2008, Maciej Sieczka wrote: > Paul Kelly pisze: > > On Sun, 10 Aug 2008, Moritz Lennert wrote: > >> Well, to be absolutely precise, you don't need linked attribute tables > >> to have multiple layers, so I'm not sure that reducing the layer > >> concept to table links is really 100% correct. > > > > I think though, that connecting multiple layers to different tables is > > the main application for layers? Are they much use for anything else? In > > which case, calling them tables makes things clearer. Perhaps even table > > would be enough - each vector map can be connected to multiple tables, > > each vector map can have multiple tables, each vector map can have > > multiple table links... is there a big difference in meaning between > > those different sentences? I feel removing the word "link" improves the > > clarity of the meaning without adding any additional ambiguity. > > I don't agree with Paul. In GRASS vector terminology the term "table" > already has a very well defined meaning and it must not be used for > anything else. > > (A "table" is an object in the database that stores the given "layer"'s > attributes, and the "table" and "layer"'s geometrical features are > linked using "key column" in which the "categories" are stored inside > the "table".) > > Regarding Moritz's remark I indeed missed the fact that the vector map > having 0 or more "layers" does not directly imply it has the same number > of data "tables". Given that, "table link" to replace "layer" as I > suggested is bad. If we are to change the term, we should do it right. > How do you like "category set" then, "catset" in short? Together with > with replacing term vector "map" with vector "layer" it would yield: > > Each vector "feature" (line, point etc.) can have 0 or more "categories" > in a vector "layer". Each "category" belongs to only 1 "category set". > Each "category set" of a vector "layer" can be connected or not with a > single database "table". The "key column" in that "table" stores the > "categories" of "features" present in the given "category set". > > Any good? > > Talking about layers (in their current meaning) - there is no convenient > tool to report the number of layers in a vector map. There is only > v.category opt=report. Could v.info be extended in this regard? Oh, and > the regular v.info already reports number of "dblinks" (which I guess > might be renamed to "table links", but I won't insist), while v.info -t > doesn't. Could this be addressed too please? > > > With regard to calling maps something different though, I think that > > would be very confusing and not a good idea (especially if they were > > renamed to layers). Map has IMHO a much clearer meaning than layer. > > There is the issue of ambiguity with a printed map I suppose, but use of > > the word in that context is kind of non-technical I feel. The use of the > > word map has a clearly defined historical meaning in GRASS (and > > influences other words too, e.g. a mapset = a collection of maps - > > should this be renamed a layerset?) and I feel that it should stay. > > Paul has points here. Yet I *guess* I'd prefer to trade legacy for > clarity anyway. Calling GRASS "maps" "layers" would improve clarity > IMHO, especially for newcommers. Word "map" has been in use for > centuries and the word immediately brings a nice picture with north > arrow, legend and stuff to my mind. "Layer" is *the* GIS word for a set > of features that can be represented graphically as a map, as well as a > table or a set of statistic properties etc. > > Maciek
+1 on Maciek's suggestions. This has been a point of controversy and confusion for some time now, and we could potentially have a nice clean start from the 7.0 branch. Cheers, Dylan -- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
