Wind and current

[Malcolm Williamson]

> GrassHopper!
> Now, I'm doing search and rescue of vessel at sea. 
> A analysis got under way and the other two wind and current rate about vessel.
> Does anyone know how can GRASS store the rate of wind and current in vector map.
> and, Does GRASS express in raster map ?
> Thanks for your help and suggestion.
> 

Shyh-yuan,
Analysis in GRASS is almost always done in the raster format. Refer to the
following references:
	GRASS4.1 Users' Reference Manual - r.mapcalc entry (available online
	using g.manual). Pay special attention to the spatial operator.

	R.MAPCALC - An Algebra for GIS and Image Processing (available by
	ftp'ing moon.cecer.army.mil - get /grass/grass4.1/documents/mapcalc-
	algebra.ps.Z)

	_Geographic Information Systems and Cartographic Modeling_ , 
	by C. Dana Tomlin (1990, Prentice-Hall) (although this book doesn't
	refer directly to GRASS, it is probably the definitive work on 
	raster-based GIS analysis).

Regards,
-- 
Malcolm D. Williamson - Research Assistant       E-mail: malcolm at cast.uark.edu
Center for Advanced Spatial Technologies      Telephone: (501) 575-6159
Ozark Rm. 12                                        Fax: (501) 575-3846 
University of Arkansas              
Fayetteville, AR 72701