Hello Markus and Paul,
I'd like to suggest to find a different word to replace "Default", "whole" is still not correct, at least for the rome40 case reported below. The paramters
towgs84=-225.000,-65.000,9.000
can "correctly" be applied only to the Sardinia island, as reported in:
http://earth-info.nga.mil/GandG/publications/tr8350.2/wgs84fin.pdf
> ---
> 4 Used in whole rome40 region
> (PROJ.4 Params towgs84=-225.000,-65.000,9.000)
> Default 3-Parameter Transformation (May not be optimum for
> older datums; use this only if no more appropriate options
> are available.)
So in this case it should be something like "Used in Sardinia island".
Now, if I understand correctly, all the parameters stored in the file "datum.table" are parsed and presented to the user as in point 4 above.
This lead to the problem of choosing a right word which can not be "Default" and could be "whole" in all the cases where the parameters parsed can actually be used for the "whole" region.
If the rome40 case is the only with local parameters, and since the are more accurate parameters available for the Sardinia island (see choice n. 2 in the parameters list), perhaps the choice n.4 could be omitted, so the user can choose only between the first 3 options.
Regards,
Alfonso Vitti
Message: 8
Date: Fri, 31 Mar 2006 17:35:49 +0200
From: Markus Neteler <neteler@itc.it>
To: grass5@grass.itc.it
Subject: [GRASS5] Re: GRASS: "default" datum parametersHello Paul,
thanks for your efforts! It's good to know that datum stuff
is no longer scattered around.Here, for the record, the same test again:
++++++++++++++++++++++++ Gauss Boaga, Italy ++++++++++++
Please specify datum name
Enter 'list' for the list of available datums
or 'custom' if you wish to enter custom parameters
Hit RETURN to cancel request>>rome40
Now select Datum Transformation Parameters
Please think carefully about the area covered by your data
and the accuracy you require before making your selection.Enter 'list' to see the list of available Parameter sets
Enter the corresponding number, or <RETURN> to cancel request>>list
Number Details
---
1 Used in Italy (Peninsular Part)
(PROJ.4 Params towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68)
Accuracy 3-4m
---
2 Used in Italy (Sardinia)
(PROJ.4 Params towgs84=-168.6,-34.0,38.6,-0.374,-0.679,-1.379,-9.48)
Accuracy 3-4m
---
3 Used in Italy (Sicily)
(PROJ.4 Params towgs84=-50.2,-50.4,84.8,-0.690,-2.012,0.459,-28.08)
Accuracy 3-4m
---
4 Used in whole rome40 region
(PROJ.4 Params towgs84=-225.000,-65.000,9.000)
Default 3-Parameter Transformation (May not be optimum for older datums; use this only if no mor
e appropriate options are available.)
---Now select Datum Transformation Parameters
Please think carefully about the area covered by your data
and the accuracy you require before making your selection.Enter 'list' to see the list of available Parameter sets
Enter the corresponding number, or <RETURN> to cancel request>> 1
++++++++++++++++++++++++ END ++++++++++++++++++++++++
Now the wording should be clear. Of course, the user *has*
to think...Thanks again
Markus
--
____________________________________________________________________________
"He who has imagination without learning has wings but no feet"
Department of Civil and Environmental Engineering
University of Trento
Via Mesiano, 77 - 38100 Trento (ITALY)
Alfonso Vitti
tel: +39 0461 88 26 08
fax: +39 0461 88 26 72
email: alfonso.vitti@ing.unitn.it
____________________________________________________________________________