Hi, i'm not sure that the raster way is the easiest, the tools are not really usable for what you want to do ...
you better have to make a new vector layer with a "height" attribute, then display it over your raster and edit the vector layer by drawing polygon/point with the height as attibute. Once ended, you will have to convert the vector to raster (v.to.rast) using the attribute "height" as raster value. I think it's the easiest way as you will be able to store the same height for many consecutive pixel without having to edit each one, and you will also be able to easily change the height if your first try is not good enought ;) cheers, Sylvain 2011/4/17 vinod kumar <[email protected]> > Hi Markus Netler, > > i want to identify buildings, trees etc.. and assign height values at > particular zoom level in a raster map and to view the data in a 3Dimensional > where i do not have any information to identify pixel graphically. > > And the problem also persists in identifying buildings and assigning height > values and to use condition like IF might not be possible as there is no > source of information. > > Thanks in advance, > nani. > > > > On Sat, Apr 16, 2011 at 11:06 PM, Markus Neteler <[email protected]>wrote: > >> On Sat, Apr 16, 2011 at 10:36 PM, vinod kumar <[email protected]> >> wrote: >> > Hi Markus Neteler, >> > >> > yes, importing pixel values with r.in ascii and patch into existing >> into >> > raster is simple easy for particular pixel, >> > but if we want to assign a height value to more pixels, for example >> > assigning height value to buildings in a >> > particular area in raster map is difficult as we don't no to which pixel >> > value we have to assign height value and >> > checking each pixel value is difficult. >> >> Now I understand a bit more: so use r.mapcalc with an if() condition. >> >> Markus >> > > > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > >
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