The most comprehensive free data I know of for Australia is Geoscience Australia's 1:250000 series dataset. This has the advantage that it is up-to-date (September 2006) and free, but does have some disadvantages:
1. It is not the raw data, but is really a description of the printed maps (although I don't think this version has actually been printed.) Thus you have to contend with cartographic correction (whereby the things you want to be most accurate -- often roads -- are those which are moved furthest from their true position). The data is not complete either -- the elevation column for contours is not populated for example. There is no linking of annotations to the objects they refer to although some of the database tables have name columns which are populated. 2. The data is at 1:250000 scale, which is probably too small for what you want. (The Spacial Database Access Policy, released in 2001, calls for the 1:100000 data to be released within 5-10 years, but I don't know what the current schedule calls for.) You can obviously print it at whatever scale you want, but features are not described precisely enough to be represented smoothly at scales larger than about 1:100000, and annotations will appear in positions apparently unrelated to what they describe. 3. The data is available based on mapsheets. In the case of Tasmania you would need to download the four sheets which cover the state. Features which cross sheet boundaries will be split into multiple features, one for each sheet and there is no way of connecting them back together. Area features will have boundaries which run along the sheet boundaries which can look funny if you print a map which crosses those boundaries. On the other hand there are some advantages: 1. The data is free. You have to "sign" an agreement which describes what you plan to do with the data, but there are no restrictions on what you can do, including commercial use. The only requirement is for some attribution. (Depending on your internet connection of course it may cost a dollar or two in ISP charges to get the data. The files vary in size up to about 7Mbytes, but 4Mbytes is more typical. The Tasmanian sheets may be a little larger because they cover more than the usual standard rectangle.) 2. The data is available in several formats: bitmapped image (ECW) and various shape formats. I've downloaded the whole of Australia over several months in the ESRI personal geodatabase format (i.e. an Access database), which is the most complete of the formats. There are 513 separate files to download whichever format you choose. (The whole of Australia fits on a single DVD when the files are compressed. With current disk sizes on personal PCs there's no problem keeping a database with all of Australia.) To get to the data you need to go the Geoscience Australia website (www.ga.gov.au). click on "Free Downloads" and then click on "Topography" and use "Tasmania" as a keyword. That should get you to all four sheets. If you would like to see what the data looks like when produced at a different scale, let me know and I can generate you a PDF (A3 or A4, portrait or landscape) centered anywhere in Australia at any scale. As an aside, if anybody has any freely available documentation on what the format of the annotation entries in the ESRI personal geodatabase files is, I'd be interested. I haven't had time yet to fully reverse engineer the format. Most of the useful information is stored in a single binary object as a single column in the table. Kevin. _______________________________________________ Geowanking mailing list [email protected] http://lists.burri.to/mailman/listinfo/geowanking
