[GRASS-dev] Starting a new location

[Helena Mitasova]

On Jul 23, 2006, at 4:52 AM, Hamish wrote:

>
>> --- discussion on how to improve starting GRASS with new
>> location------- I looks like this may not be as difficult as  
>> percieved
>> if we take into account what the user has before he starts to work
>> with GRASS:
>
> [a pull-down menu would be nice here]
>
>> User who wants to start grass may have:
>> 1. georeferenced file with prj info
>
> we already have a button on the startup GUI for this one,

if you read the entire email - I am suggesting to make this the first  
choice
rather than the last one to encourage users to go this way
>
>> 2. georeferenced file but no prj - should we try to guess the coord.
>> system - lat/long would be easy, UTM maybe?, state plane would be a
>> lot of work, I don't know about the rest of the world.  I don't
>> think that you can guess a datum?
>
> Please, no. We shouldn't even infer lat/lon from data range. If in
> doubt, default to XY.

this was in response to Michael Tiemann's suggestion, see below
(Michael it cannot be done the way you describe, but I believe that  
this problem will be eventually
solved when every georeferenced file that general public would use
will have the prj and extent info associated with it - we are not  
that far from it.
If my optimism has any merit, the implementation of the guessing  
procedure may
not be worth the effort and most users will go with no.1 that does  
everything
automatically)

 >Michael T writes:
 >And/or some script-based help that can provide some guidance, such as
 >"this looks like a GIS file associated with the US Census TIGER
 >database.  If this is correct, your projection is likely $PROJ and  
your
 >extent is likely $EXTENT.  Should I use those values?"  Or, "this  
looks
 >like a GIS file associated with a Magellan GPS device.  If this is
 >correct..."

 >I believe that there are a few simple use cases--electronic  
versions of
 >USGS maps, GPS reference data, etc--that cover literally millions of
 >intelligent, but not sophisticated, users.  These users don't
 >necessarily need toolbar help in figuring out which band of LANDSAT  
data
 >they want to overlay, but they do want to map demographic or geocache
 >data, and it would be HUGE if GRASS made it as easy as possible to be
 >successful in those two use cases.

>
>> 3. non-georeferenced file
>
> simple XY location

should we have separate button for it on the startup pannel?
>
>> 4. nothing - can this happen?
>
> often we start with no data, but know the proj info or EPSG code.

no data but a prj info would be the same as no. 2, so that would be
"Use pre-defined projection" (or should it be pre-defined coordinate  
system?)

> First data arrives with e.g. i.rectify or m.proj.
>
>> 2. "Use EPSG values" would stay second choice but we can make it
>> more user friendly:
> ..
>> - is it possible to make EPSG list searchable?
>
> hear hear. "/" search or simple "find text" dialog please..
> currently the browse EPSG file is pretty useless as it is so long.

searchable EPSG file would solve a lot of problems - does anybody know
how to implement it?

Helena
>
>
>
> Hamish