grass4.0 performance

[Chris C Rewerts]

>From lists-owner at amber.cecer.army.mil Tue Jul 21 17:36:58 1992
>From: JARDOT at TAMUSDA.TAMU.EDU
>Subject: Re: grass4.0 performance
>
>Also, I have been told several times that GRASS is not good at working with
>raster maps.  This is in reference to computations, statistics, etc.  This 
>is apparently the opposite of what most people think.  Which is true?
>
>Kelly
>

Good question, since it points to the need for GIS users to understand
more than command syntax. The real point may not be in playing favorites
to given systems, but in their thoughtful utilization.
I venture to say that (today) it is incumbant on the user of a GIS to know
the nature of the programs s/he uses to manipulate their maps.

(e.g. when an 30X30 meter resolution elevation map (DEM) is resampled
to a 120X120 meter resolution, how are the values for each raster
cell obtained from the 16 cells in the input map? by mean? mode? centroid?
How does this match what they expect to be done? What if it was a soils
series or aspect map instead of a DEM?)

IMHO, it is very tricky to rank GIS into bipolar (good/bad) terms. Each
will have a variety of strengths and weaknesses. The trick is to find the
best fit to the needs of whatever it is that you intend to use it for.
Another big issue is data, since it can cost many more times the cost
of the GIS software and hardware... but that is another story.

Off the top of my head, a good place to start for learning more 
about GIS assessment would be:
"A process for evaluating geographic information systems" 1988. Stephen
Guptill, ED. U.S. Geological Survey Open-File Report 88-105. 

Chris Rewerts
Agricultural Engineering, Purdue University