[GRASS-user] Re: import a folder full of shapefiles and reproject on-the-fly?

[Michael Barton]

On Jul 30, 2008, at 6:53 AM, <grass-user-request at lists.osgeo.org> wrote:

> Date: Wed, 30 Jul 2008 15:53:50 +0200
> From: "Markus Neteler" <neteler at osgeo.org>
> Subject: Re: [GRASS-user] Re: import a folder full of shapefiles and
> 	reproject	on-the-fly?
> To: "Tim Michelsen" <timmichelsen at gmx-topmail.de>
> Cc: grass-user at lists.osgeo.org
> Message-ID:
> 	<86782b610807300653j48a077a9u50248468a699e319 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hello Tim,
>
> On Tue, Jul 29, 2008 at 11:41 PM, Tim Michelsen
> <timmichelsen at gmx-topmail.de> wrote:
> ...
>> Nevertheless, I cannot get around expressing my disappointment about
>> GRASS in this area.
>> * I cannot just point the program to a directory of shapefiles and  
>> tell
>>  it import all. QGIS, gvSIG and ArcGIS can do this.
>
> We could easily add v.in.ogr.all or v.external.all, I suppose two or
> three lines of shell script :) Could be stored in the Addons wiki.
>
>> * I cannot reproject these on the fly be changing the projection of  
>> my
>> location.
>
> Yes, because it was decided to not support that (see archive of this  
> list).
> And, using QGIS I regularly *fail* to do this job.
>
>> => Whenever it comes to data format conversion and reprojection  
>> people
>> on QGIS/GRASS Maillists tend to tell the user: get your keyboard and
>> hack something with OGR/GDAL (Re: converting .asc to .xyz,
>> http://permalink.gmane.org/gmane.comp.gis.qgis.user/2519).
>> In clear words this means that the software is not ready, yet.
>
> I don't agree. You can easily import and reproject single maps even
> with the various d.m/gis.m/wxpython user interfaces:
> - create new location *graphically* from startup menu, now even with
>  location wizard.
> - run r/v.proj
>
> Not too much keyboard needed here.
>
>> This tells me that these GIS are not made for "normal" Desktop GIS  
>> task
>> and mapping.
>> Maybe GRASS is good for some very specialised and automatisable  
>> tasks.
>> But to make a beautiful and printable map from a buch of data that  
>> can
>> be interpreted?
>
> see
> http://grass.osgeo.org/wiki/WxPython-based_GUI_for_GRASS#Cartography_tools
> -> work in progress
>
> ...
>> Why did I write disappointment? Because GRASS is advertised by  
>> OSGEO as
>> THE most powerful free GIS that can perform any task.
>
> Where did you see "any task"?

This is a good reply. No GIS software that I know of is good at  
everything. ArcGIS has great cartographic tools, but is limited for  
processing raster files. GRASS can make very nice looking maps (I've  
published some in leading journals), but lacks easy cartographic  
layout (that is, it has the tools but they are not point and click).  
However, it's raster processing is superb and easy.

There has been a lot of discussion about on-the-fly reprojection. The  
consensus from experience with programs that offer it is that it is  
very convenient for making maps for display, but very problematic for  
any uses that require geospatial precision. GRASS has chosen to  
implement projection protocols and algorithms that ensure accuracy. It  
also supports an enormous array of projections.

Combining gdal with a large array of additional internal drivers,  
GRASS can import and export more GIS formats than any other program I  
know of. Importing a directory full of ESRI shape files is a task that  
some people encounter, but many more do not. If there is enough demand  
for this, someone will end up writing a module or script that everyone  
in the community can use. That's one of the great things about open  
source GIS.

While often a response will reference a GRASS module by name (e.g.  
r.in.gdal), all can be used via GUI interfaces and almost all are  
accessible from the main GRASS GUI. Suggestions that suggest to 'get  
your keyboard and hack something' usually are pointing out that if a  
fuction is not already built into GRASS, a user can create his/her own  
pretty easily. With most GIS software, what you see is what you get  
and what you are stuck with. As a Mac user, I'm a big fan of GUI's--to  
such an extent that it might annoy my colleagues on the development  
team at times ;-). Nevertheless, I'm also an equally big fan of  
GRASS's enormous flexibility and ease of creating scripts that combine  
GRASS commands in new ways. By way of a couple personal example, GRASS  
has no inherent way of creating a graphic output file of one of its  
displays. So the first script I ever wrote, combined GRASS commands to  
create that function. While there are now various ways of achieving  
this, the descendent of that script (d.out.file) is still useful to  
many. My research team has created one of the most sophisticated and  
fastest landscape dynamics modeling tools that I've seen or read of-- 
capable of simulating erosion/deposition over centuries and across  
watersheds of millions of cells in response to climate and vegetation  
change. We did it simply by chaining together GRASS commands in scripts.

GRASS is not good for any task. But it is very useful for many of the  
tasks involved in the processing, analysis, and display of geospatial  
data. In comparison with other similar software--and there are many  
good packages and some not so good ones--it's as 'prime time' as it  
gets.

Michael