On Sat, 30 Jan 2010, Dylan Beaudette wrote:
Where did these data come from?
Dylan, USGS, BLM, USFS. I have the Hydrography Data Dictionary so I need to closely read it and find which ancillary tables have the relevant data. It turns out that there's a lot of it. For the water courses (linear, flowing aquatic systems), we're told, "This feature has been modeled to allow for flow modeling. All arcs must point downstream. This layer will be routed using the LLID identifier for the stream. All associated attributes are stored as event tables on the LLID routes. The stream routes are indexed starting from 0 at the mouth of the stream to some maximum value at the headwaters. All route measures will be initially calibrated in kilometers to three decimal places. As these routes are edited, every effort will be made to keep the measure value at a given map location from shifting. This will be accomplished by stretching or shrinking the measure values to accommodate lengthening or shrinking along the route as its X,Y coordinates are edited." There is also an E-R diagram that graphically shows the relations among tables and columns associated with the map table. So, I need to look for the tables with segment lengths and write a SELECT statement to get all relevant rows and sum the lengths. More when I have questions, Rich _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
