HARPER@opmvax.csc.fi (Robert Harper (Finland)) (06/22/89)
In article <8906191818.AA04227@net.bio.net>, GORENTZ@msukbs.bitnet writes: > The digitizing you describe is a subset of what is done by the input modules > of GIS (Geographic Information System) software. I just happened to have a friend at the geograhpy department at Helsinki University who is interested in ARC/INFO. Here is a short report on what they use at that department. I hope some of the info might be useful. -------------------original------------------------------------------ From: HYLK::BLOM "Tom Blom / D. of Geography, Helsinki U, Finland" Subj: GIS software Hello! I heard from Pellervo Kokkonen that you have been asking about GIS software for some specific application. ARC/INFO and other similar software packages can be used for digitizing but they can do a lot more. If the task is to digitize polygons (or lines or points) and do some specific calculations they are perhaps too "heavy" and you must be prepared to spend quite a lot of time to learn to use the system. For "simple" GIS applications you can also use CAD software. What is special to GIS software is 1) Topology, i.e. information about the relative location of spatial features like connectivity of lines 2) Attribute information about spatial features. Attribute information is usually stored in a relational database. For example, ARC/INFO always stores the area of polygons to database when topology is created from digitized "spaghetti". If you need to calculate measures of spatial dispersion and other spatial statistics you'll probably have to find more specialized software. If locational accuracy is not very important, you can also use raster-based GIS software. The study area is divided in a regular rectangular grid and every grid cell is coded with a attribute code. Raster-GIS software is much cheaper and easier to use than vector- based software. You can also use scanners to input data from maps and other pictures instead of using a digitizing tablet. At the Department of Geography we have a raster-based GIS software called IDRISI. It costs US$ 100 for univerities and includes modules for spatial statistics. I'm glad if I can help more about GIS problems Tom Blom EARN/BITNET BLOM@FINUHA