On Sun, 2007-10-07 at 23:08 +0100, Dave H wrote: > O.k thanks for that - I'm no geo-whatever expert - in fact most of the > acronyms > floated in here mean very little - i suspect to many this side of the > Ocean.
I am a geo-whatever expert. ;-) Most of acronyms used here are used in the Geographic Information Systems (GIS) and geo-informatics industries. It's a small, large industry in the sense that it is everywhere, yet few have heard of it. > It seems to me your so lucky in the US that your public-tax-$ > investments in > geo-data collection - the data seems to be handed back freely back to > you.. > Certainly in the UK either we have no of our own or its damn-secret or > we > have to pay a second time. This is true that the US has been inherently blessed in the past with good quality data. This is changing at a fast (and IMO, alarming) rate. There really hasn't been truly freely available orbital data since LANDSAT-7 and the SRTM shuttle mission. Street and feature data extracted from Census data is really a byproduct of the Census, complete with varying amounts of error. This error can be easily demonstrated on this page a friend did on the subject: http://casoilresource.lawr.ucdavis.edu/drupal/node/433 I've suggested that at a minimum, OSM should include metadata specifying projection parameters, but it falls on deaf ears. It would be much better if users either uploaded data consistently (and rejected outliers) or the system reprojected upon upload. OSM may be a useful last resort for Xastir in areas where better data does not exist. > Xastir in the UK is often poor looking simply due to lack of decent > map sources > and probably zero overlays. Either we don't have them or some buggers > got > copyright over things we paid for once already. We get desperate or > use outlines > for lack of much else. Aside from Census data, that is largely the case here in the States, too. I don't know how things of this nature function in the UK, but here we are able to request data from local municipalities. I've had no trouble getting needed data for projects that local governments have collected. Have you tried asking various levels of government for a Shapefile of roads? Try asking for street center-lines, first. They are generally high accuracy. Be specific of what you want so that you aren't creating work that they don't need to do...and they might respond to you favorably in the future. -- Brad Douglas <rez touchofmadness com> KB8UYR/6 Address: 37.493,-121.924 / WGS84 National Map Corps #TNMC-3785 _______________________________________________ Xastir mailing list [email protected] http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
