********************************************************************** * IMPORTANT NOTE: * * * * r.proj runs with fp-GRASS only. * * Save your time and don't try to compile it if you are using * * GRASS4.1!!! * * * ********************************************************************** r.proj() Misc. Reference Manual Pages r.proj() NAME r.proj - projects raster maps between two projections (GRASS Raster Program) SYNOPSIS r.proj r.proj help r.proj input=name location=name [output=name] [mapset=name] [dbase=name] [method=name] [res=value] DESCRIPTION r.proj projects a raster map in a specified mapset of a specified location from the projection of the input location to a raster map in the current location. The projection information is taken from the momentary PROJ_INFO files. COMMAND LINE OPTIONS Parameters input=name input raster map. location=name location of input map. output=name output raster map (default: same name as input map). mapset=name mapset of input map (default: same name as current map- set). dbase=name database of input map (default: current database). method=name interpolation method to use options: nearest, bilinear, cubic default: nearest res=value resolution of output map (default: calculated from the number of cols in input map). NOTES r.proj uses three alternative resampling algorithms: nearest - nearest neighbor bilinear - bilinear interpolation cubic - cubic convolution SunOS 5.4 Last change: 1 r.proj() Misc. Reference Manual Pages r.proj() The nearest option, which performs a nearest neighbor assignment is the fastest of the three resampling methods. It is primarily used for categorical data such as a land use classification, since it will not change the values of the data cells. The bilinear option determines the new value of the cell based on a weighted distance average of the 4 sur- rounding cells in the input map. The cubic option determines the new value of the cell based on a weighted distance aver- age of the 16 surrounding cells in the input map. The bilinear and cubic interpolation methods are most appropriate for continuous data and cause some smoothing. Both options shouldn't be used with categorical data, since the cell values will be altered. If nearest neighbor assignment is used, the output map has the same raster format as the input map. If any of the both interpolations is used, the output map is written as float- ing point. BUGS The entire input map is read into memory. This requires a large amount of memory if large raster layers where pro- jected. SEE ALSO r.bilinear, r.resample, s.sample, v.proj AUTHOR Martin Schroeder University of Heidelberg Dept. of Geography emes@geo0.geog.uni-heidelberg.de REFERENCES Press, W.H. et al. (1992), Numerical Recipes in C, Cambridge University Press, Cambridge, 2nd edition. Richards, John A. (1993), Remote Sensing Digital Image Analysis, Springer-Verlag, Berlin, 2nd edition. SunOS 5.4 Last change: 2