Hi Alyre, In the maritime community, I think GMT )Generic Mapping Tools: http://gmt.soest.hawai.edu) is more widely used than GRASS, espacially for publication quality map output.
It has very effective tools for generating & manipulating grids (DEMs) & both plotting contours directly from the grid (optionally smoothed - perhaps useful for your 0 contour) & generating contours as vectors from them. OGR (ogr2ogr) can convert to/from GMT vectors, & with some fiddling, it can also create GMT grids from other rasters, although you may find ir easier to work entirely with GMT & to generate your grid in GMR from your source point data. If you are interested, send me the original data and I can scribble out a quick script to demonstrate this... Cheers, Brent Wood Brent Wood DBA/GIS consultant NIWA, Wellington New Zealand >>> Alyre <alyre.chias...@umoncton.ca> 05/15/09 5:46 AM >>> Hello, I am trying to create a bathymetric map of a small pond. I have imported the depths and digitized the outline of the shore (0 depth contour). I believe in GRASS both would by default be in vector format and I need to transform them into raster and merge both files. I have successfully converted the shoreline into raster form but it appears as a solid area as if the whole polygon that enclosed the pond was transformed and not the outline. What I need is to convert the outline of the polygon to a series of raster points and be able to define the spacing. The spacing of the 0 contour points appears to me to be important as it will influence the interpolation of the contours when the transect depths are added. In addition I am not sure how to assign the additional attribute of depth (which would be zero) in the transformation process or how to add it afterwards. From what I understand in GRASS, points are actually vectors but to do contours everything has to be in raster format. So I assume I will have to convert the depths (x,y,z) into raster format as well then merge the two raster files (shore outline of zero depth with depth transects). I assume GRASS is widely used to do bathymetric maps, a bit like elevation contours but with negative values. If anyone knows of a tutorial or step by step guidance at a beginner's level that would be most helpful. The bathymetric map is only a support element of a large fish distribution study but is turning out to be much more difficult to achieve than expected. Thanks Alyre -- View this message in context: http://n2.nabble.com/Help-with-creating-bathymetric-maps-tp2896653p2896653.html Sent from the Grass - Users mailing list archive at Nabble.com. _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user NIWA is the trading name of the National Institute of Water & Atmospheric Research Ltd. _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user