[GRASS-user] GRASS Location covering multiple UTM zones and SpatiaLite

[Bulent Arikan]

Hello Stefan,

As Markus mentioned, although SpatiaLite uses SQLite, it is a different
entity. In the past, I used native dbms of GRASS. For the new project, I am
thinking of switching to SpatiaLite, if it would be practical. The aim here
is to record settlements (points), weather stations (points), stream
network (lines), and basins (polygons) in one db to make some calculations
easier; rather than extracting data from GRASS, exporting them into a
separate SpatiaLite file. analyzing, and putting data back into GRASS'
attribute data. It seemed to me that doing it with SpatiaLite would be
easier but I am open to suggestions. I just started so I want to make sure
that I build this right.


As for QGIS (2.18.2) - GRASS (v. 7.0) issue –running on Mac OS 10.10.5
Yosemite–, when I install GRASS plugin, the default path for GRAS
installation files is set to " /Users/Shared/unix/grass-qgis-mtlion/grass-7.0.4
". I do not have GRASS installation files there and this creates an
initiate error "GRASS init error: GRASS cannot found..." The only folder
related to GRASS in my Users folder is "grass_dev" (sub-folders for v.6 and
v.7) and some read-me files. I saw on the internet that some people
suggested to move (,app) icons out of the folders but I am not certain
because it was an old email thread.

When I provide the correct path: AFAIK it is " /Applications/GRASS/GRASS-7.
0.app/Contents/MacOS "  that does not seem to resolve the issue. All GRASS
versions I have are kept in one folder titled GRASS under Applications. So,
I am not sure how to solve this one.

BÜLENT

On Tue, Mar 28, 2017 at 11:32 AM, Blumentrath, Stefan <
Stefan.Blumentrath at nina.no> wrote:

> Hi Bülent,
>
>
>
> GRASS 7 uses SQLite for attribute management by default, so except for the
> spatial part the DB backend it is identical. And a couple of modules can
> handle points without topology.
>
> If you give us more information on what exactly you are planning to do
> with your vector data it would be more easy to suggest a solution… E.g. are
> you using polygons as input or output? What are you going to do with them…
>
> BTW. it should be fully possible to load GRASS data in QGIS 2.18. What is
> your OS and GRASS version and what is the “path” issue you mentioned?
>
>
>
> Cheers
>
> Stefan
>
>
>
>
>
>
>
> *From:* Bulent Arikan [mailto:bulent.arikan at gmail.com]
> *Sent:* tirsdag 28. mars 2017 09.37
> *To:* Blumentrath, Stefan <Stefan.Blumentrath at nina.no>
> *Subject:* Re: [GRASS-user] GRASS Location covering multiple UTM zones
> and SpatiaLite
>
>
>
> Hi Stefan,
>
>
>
> Thank you for your response! I guess that makes sense and I will define a
> location for UTM 36 since it covers the majority of the region as well as
> it is between 35 and 37. That would probably help to keep any distortion at
> minimum.
>
>
>
> I understand that there is still not full compatibility with SpatiaLite,
> so I will probably think something else.
>
>
>
> Cheers,
>
>
>
> BÜLENT ARIKAN
>
> Assistant Professor
>
> Department of Ecology and Evolution
>
> Eurasia Institute of Earth Sciences
> Istanbul Technical University
> Maslak-Sarıyer
> Istanbul
> 34469
>
> Turkey
>
> http://web.itu.edu.tr/~bulentarikan/index.html
> [image: cid:image001.jpg at 01D2A7AA.458E7A90]
>
>
>
> On Mar 28, 2017, at 10:07 AM, Blumentrath, Stefan <
> Stefan.Blumentrath at nina.no> wrote:
>
>
>
> Hi Bülent,
>
>
>
> Here in Norway we face the same situation. The country covers UTM zones 31
> to 36. However, the standard the public authorities suggest is to use the
> average (UTM 33) when running analysis on the whole country.
>
> Of course this leads to imprecision and distortion, but if that is
> significant or not depends on your application (esp. scale of the problem
> you are going to solve)…
>
>
>
> Since GRASS has a topological vector format, linking external vector data
> can cause issues in your analysis, esp. with polygons. However, points can
> be fine in many cases… Please have a look at the mauals of v.external [1]
> and v.external.out [2].
>
>
>
> Cheers,
>
> Stefan
>
>
>
> 1: https://grass.osgeo.org/grass72/manuals/v.external.html
>
> 2: https://grass.osgeo.org/grass72/manuals/v.external.out.html
>
>
>



-- 
Asst. Prof. BÜLENT ARIKAN
Department of Ecology and Evolution
Eurasia Institute of Earth Sciences
Istanbul Technical University
Maslak-Sariyer, Istanbul
TURKEY
34469
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