[GRASS-user] Re: ArcGIS vs GRASS notes

[Alex Mandel]

I can clarify some of the questions...
Arc has dropped Visual Basic in favor of python, in the current 10.x
series though python can only interact with tools in the toolbox (making
it quite similar to how GRASS works). Anything more directly using Arc
libs to build applications at the low level requires .Net.

Personally I like to explain it as GRASS fills the same role typically
filled by Spatial Analyst, 3D Analyst, Network Analyst and Imagery
Analyst (All add on extension to Arc). While not 100% equivalent it's
similar enough in feature set. I also tend to recommend a combo of QGIS
as the data prep/viewer/map maker and GRASS (not via plugin) as the
backend analysis workhorse.

For general Raster analysis that uses existing tools GRASS is a great
option. In the course I help with we've avoided it though because the
Location/Mapset concept throws too many students into confusion early
on. Instead we've followed a course similar to the Utah one on how to
use GDAL/Numpy, which gives students more of a feel for how to iterate
over raster data and learn to deal with it in chunks or rows to avoid
memory issues, so they better understand how raster algorithm
development works.
http://www.gis.usu.edu/~chrisg/python/

I need to talk with my Professor about getting our updated version online.

Thanks,
Alex

On 04/02/2012 10:40 AM, Michael Barton wrote:
> I don't know of any such comparison, but you could write the user and developer lists to see if there is one. I haven't kept up with Arc scripting in recent years. I believe they switched from their own OOL to Visual Basic. However, I've recently heard things that suggest you can script in Python too (but I'm not sure about that).
> 
> With GRASS, you can script in about anything that will interact with the shell (or DOS window) in some way. In recent years, we've emphasized Python over BASH, creating many convenience classes and methods in Python for GRASS scripting. 
> 
> I'm not sure of the level of your students. But if this is also an introduction to GRASS and advanced GIS, I think it will make it much harder for them to learn if you keep them from using the GUI. An important aspect of the GUI from the point of view of scripting is that it is designed to help users learn command-line tools and scripting.
> 
> 1. All GUI dialogs for commands have the option of copying the command and its arguments so that it can be pasted into the command line or into a script. 
> 
> 2. Additionally, the GRASS command console provides a rich hinting environment (with autocompletion and tab to get command syntax) for issuing GRASS commands. 
> 
> 3. Finally, the new graphical modeler is an excellent tools to start scripting. You can create chains of GRASS commands--complete with user interaction and recursion--with graphical tools, test them, and then save them to Python scripts that can then be enhanced. There are not many written docs for this yet, but there is an excellent set of You-Tube videos on their use that should be very helpful for students. 
> 
> Michael
> 
> 
> On Apr 1, 2012, at 8:15 AM, Doc Robinson wrote:
> 
>> Professor Barton,
>> I very much liked your posting comparing ArcGIS with GRASS for the new 
>> user. I was wondering if you have run across a good summary comparing 
>> the two with regard to scripting for complex raster processing problems?
>>
>> I going to introduce some of our graduate students (a couple from 
>> Anthropology as well) to GRASS 6.4.x but not the GUI...just the text
>> CLI so they concentrate on script writing.
>>
>> thanks in advance
>> -- 
>> Regards,
>>
>> Doc
>> <doc_robinson.vcf>
> 
> _____________________
> C. Michael Barton
> Visiting Scientist, Integrated Science Program
> National Center for Atmospheric Research &
> University Corporation for Atmospheric Research
> 303-497-2889 (voice)
> 
> Director, Center for Social Dynamics & Complexity 
> Professor of Anthropology, School of Human Evolution & Social Change
> Arizona State University
> www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu