[GRASS-user] Re: ArcGIS vs GRASS notes

[Benjamin Ducke]

On 04/02/2012 08:00 PM, Alex Mandel wrote:
> 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

If you use GRASS via SEXTANTE and gvSIG, then you have all in one
package and no need to manage a location/mapset:

   http://www.oadigital.net/software/gvsigoade

Basically it's like ArcView 3.x, plus all the "[PayALotOfMoney] Analyst"
extensions (Raster, Network, etc.).

I have used the above in many GIS training courses, as an integrated
software platform for students with different backgrounds, interests
and skill levels. I have also successfully replaced ArcGIS 10 with
the above for very demanding land use/management and data analysis
projects.

Best,

Ben

> 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
>
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-- 
Benjamin Ducke
{*} Geospatial Consultant
{*} GIS Developer

   benducke at fastmail.fm