For the last few days, there have been several messages referring to XGEN and
its lack of use in `serious' applications:

> As far as XGRASS and xgen go in general, I think that very few serious users are
> working with it. We use it for introductory training, where it has obvious 
> strengths. A few days ago someone at CERL stated in a post that no one there
> is currently actively supporting XGRASS. So, draw your own conclusions...

We at ASSIST (Academic Support for Spatial Information Systems) have been
working with XGEN for a couple of years now. We have been producing a ~major~
tutorial - SITE (Spatial Information Tutorial Environment) for teaching some
of the fundamentals of Spatial information processing.

SITE is essentialy an XGEN interface that sits on top of GRASS with a series
of workbook exercises. It is designed for those who wish to gain a fuller
understanding of GIS technology and some of the theory behind its use. It 
can also be used as an interface to GRASS in its own right, perhaps as an
alternative to XGRASS.

It is due for public release this Spring, and will be distributed at the
cost of materials (approx 100 pounds)

For more information on this or any other of our GRASS related tutorials,
Email RRL@leicester.ac.uk, FAO Jo Wood / Jason Dykes.


Jo Wood
Academic Support for Spatial Information Systems
Department of Geography,
University of Leicester
Leicester LE1 7RH
UK.


rom grass-lists-owner@max.cecer.army.mil  Sun Feb 20 15:39:55 1994
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Date: Sun, 20 Feb 94 10:07:46 EST
From: jianp@ocean.rutgers.edu (Jianping Xu)
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Subject: Re: d.histogram problem

> Has anyone noticed that histograms produced by d.histogram
> can be significantly different when they are drawn on display frames
> of different sizes?
> 
> For example, given a raster called "dem", create a histogram 
> using the entire graphics screen.  Then, use "d.frame -c" to make 
> a smaller frame in the top-left margin.  Draw another histogram of dem
> in the new frame without erasing the first one.
> 
> When I do various repetitions of the above, using different-sized
> frames, I get vastly different results at times.  I'm using 4.1, but
> not the latest release.

I have not found the OVERALL changes of the histograms but the x-axis 
unit and y-axis unit. The later changes result from the changes of 
display frames. (I am using version 4.1)

Jianping Xu

