<br><div class="gmail_quote">2011/7/27 Rich Shepard <span dir="ltr"><<a href="mailto:rshepard@appl-ecosys.com">rshepard@appl-ecosys.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
I have a map of drainage basins and another of the project property<br>
boundary. Of the 4200+ basins in the map, the property is in only a dozen or<br>
so. I'm trying to overlay these maps to produce a union that has only those<br>
basins that drain the property. v.overlay with operator=or yields a combined<br>
map of _all_ basins and the property[1] so either I'm not correctly applying<br>
the module, or the resulting map needs more processing with a different<br>
module. Please point me in the right direction to get the results I want.<br></blockquote><div><br>there are different ways for that job, one is using r.water.outlet which compute the drainage area for a specified point: get to coordinates of the outlet point of your drainage area, and it will compute one unique corresponding catchment area !<br>
<br> <br></div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
After I have a map containing only those basins overlaid by the property<br>
boundary I want to use v.overlay to clip the stream networks in these same<br>
basins. I assume that v.overlay with op=and will do this nicely. My question<br>
is then what process will allow me to extract each drainage basin with its<br>
stream network and portion of the property for terrain and hydrological<br>
analyses and modeling.<br></blockquote><div><br>transform the resulting catchment area raster into an area vector (r.to.vect), then use v.select or v.overlay to query the stream netwok that is contains into the cathment area ...<br>
<br></div><div><br></div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
[1] Using the wxPython GUI with v.overlay I did not see a data entry widget<br>
to select the operator. It apparently defaults to 'or' but if there's a<br>
radiobox to select 'or,' 'and,' 'not,' or 'xor' I did not see it.<br></blockquote><div><br>in the command dialog box, there are several tabs. One is called "Options", and there is a list box "Operator defines features written to output vector map" which permit to select the different avaliable operator ...<br>
<br><br><br>Sylvain <br></div></div>