Moritz et al, Thank you for the helpful suggestions. One of the problems I have is that about half of the points are in a tidal estuary where the elevations are all zero (sea level); so utilizing the elevations to sort will not work -- I have several thousand points I'm dealing with, which I obtained by doing a vect-->rast conversion and then got the points from the rast (I know this sounds screwy).
I have to explain what I'm doing. I want to use r.inund.fluv to generate a flood inundation map. The problem stems from the fact that I have a USACE HEC-RAS model implementation which was not georeferenced, from which I have modeled water surface elevations from a historic flood. From an ascii output file, I basically have the channel centerline locations (x,y) and water surface elevations and I have calculated the distance to the river mouth at each point. In GRASS I have independently, using a UTM map projection, the channel centerline as a vector. I have also identified the corresponding upstream and downstream end points, which identify the same locations -- so I plan I 'mapping' the HEC-RAS water-surface elevations (WSEL) at the un-georeferenced channel centerline locations based on scaling the entire river reach length between this data and what I have in GRASS. I can use the scaled distance from the river mouth to spatially interpolate locations where I know the WSEL. The GRASS addon command r.inund.fluv needs X, Y, WSEL as an ascii file. Now if I can go directly from the GRASS vector centerline and output verticies of that feature, so I have the x,y locations of the verticies my problem would be solved. I looked at v.distance and other modules but could not see how to generate the verticies and export them -- but, in the end, I need an ascii file of centerline point locations in upstream to downstream order. I have/am writing Perl scripts to manipulate the data. I was afraid the order would not be preserved by v.out.ascii, which was confirmed by my script that calculated the distances from the river mouth when I saw them starting to bounce around in odd ways as I looked at the calculated values when I looked at the downstream to upstream distances. Cheers! Tom On Tue, Apr 15, 2014 at 5:21 AM, Moritz Lennert < [email protected]> wrote: > On 15/04/14 08:13, jctorres wrote: > >> Hello >> >> You can create a map of these points contining the elevation as >> attribute. Once you output this map you could sort points using the >> elevation values. >> >> you can do this for instance using v.to.rast to convert the points to >> raster, them combine this map with elevation using r.mapcalc (assigning >> elevation to the points), and them output the map using r.out.xyz. >> To sort the points you can use any sort program or a spreadsheet. >> > > Maybe directly using v.what.rast might be easier... > > And, Thomas, have you checked the category values of the points ? If the > points were created in stream order than the cat values should give the > correct order. > > Moritz > > > >> >> Best regards >> >> Juan Carlos Torres >> >> El 15/04/14 04:52, Thomas Adams escribió: >> >>> All: >>> >>> I have a collection of points that represent the centerline of a >>> river. I need to output them in upstream to downstream order (or the >>> reverse). A simple v.out.ascii does not do this because of the channel >>> meanders. It's critical to get the x,y locations of these points in >>> the correct order. >>> >>> Any help is appreciated! >>> >>> Regards, >>> Tom >>> >>> -- >>> >>> >>> >>> _______________________________________________ >>> grass-user mailing list >>> [email protected] >>> http://lists.osgeo.org/mailman/listinfo/grass-user >>> >> >> >> -- >> >> ======================================================================= >> Juan Carlos Torres |http://lsi.ugr.es/~jctorres >> Laboratorio de Realidad Virtual | Tlf.: (+34) 645 885 167 >> Dpto. Lenguajes y Sistemas Informaticos | (+34) 958 249 307 >> ETS. Ing. Informatica | interno ugr 71 260 >> Univ. de Granada | FAX: (+34) 958 243 179 >> ======================================================================= >> >> >> >> _______________________________________________ >> grass-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/grass-user >> >> > >
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