[GRASS-user] Re-organizing Project

Rich Shepard rshepard at appl-ecosys.com
Tue Dec 22 20:35:00 EST 2009


On Wed, 23 Dec 2009, Glynn Clements wrote:

> There is no real advantage to using multiple locations with the same
> projection unless they are used for entirely separate projects where you
> will never (or, at least, rarely) need to use data in one location from
> within a different location.

   Thank you, Glynn. That's finally made sense to me.

> How to use mapsets is a judgement call. If the data is shared between
> multiple users, each user needs their own mapset (you can only select a
> mapset as the current mapset if you own the mapset directory). Similarly,
> if you want multiple concurrent sessions, each session really needs a
> separate mapset so that sessions don't end up stomping on each other's map
> and WIND files.

   I'm the only user and can work with a single session.

   If I correctly interpret your preference it's to have a single location
(e.g., Oregon in my situation) with mapsets for each theme map. Nothing in
PERMANENT other than the default window and projection information. That's
what I'm trying to do. Daniel likes everything in PERMANENT but the specific
project directory, and that's just a different way of organizing.

> There's no reason to use *.proj when the source and destination location
> are the same. You can just copy/rename maps between mapsets, or you can
> just leave them where they are and use the map at mapset syntax and/or the
> mapset search path (g.mapsets).

   The source and destination locations are different. I'm trying to collect
the different locations into one by using v.proj and r.proj. That's not
working properly.

> If you have several specific regions of interest, you can create named
> regions with "g.region ... save=...", then subsequently select a named
> region as the current region with "g.region region=...".

   Within a specific location? Isn't the region reflected in the mapset's
WIND file? What I think I want to have is location=Oregon with
PERMANENT/DEFAULT_WIND == the entire state (using the state boundary map as
the source), PROJ_INFO and PROJ_UNITS set as the Oregon LCC since that's
what the state uses.

   Then within that location I can have a mapset for each theme map, and
another one for the project itself. The region of each mapset would be set
as the local WIND ... or would it change the location's region?

   Finally, I can eventually define the region/WIND for the project drainage
basin which is another mapset in the Oregon location.

   Lot's of options and opinions; I'm learning a lot from all of you, and
this far exceeds what I knew way back when. I'm grateful for the education.

Rich

> The DEFAULT_WIND file offers a convenient way to restore the current
> region to cover the entire dataset, but it isn't any more than that,
> and nothing actually requires data to fit within the bounds defined in
> the DEFAULT_WIND file, nor is the current region constrained by it.

   So for my purposes I should set DEFAULT_WIND to the WIND of the state
boundary mapset as that's the reference for all subregional work. Correct?

Again, thanks,

Rich


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