SmartProject

The Problem

In interactive mode, PROJECT uses the inherent defined projection and only asks for the output projection description:

   Arc: project cover incov outcov

   **************************************************
   *      The INPUT projection has been defined.    *
   **************************************************
   Use OUTPUT to define the output projection and END
   to finish.
   Project:

In non-interactive mode you must define the input and output descriptions in an external file like this:

Arc: project cover incov outcov \path\to\dd2albers.prj

Where "dd2albers.prj" looks like:

      INPUT
      projection gegraphic
      units dd
      datum nad83
      parameters
      OUTPUT
      projection albers
      units meters
      datum nad83
      paramaters
       61 40  0.000 
       68  0  0.000 
      -132 30  0.000
       59  0  0.000
      500000.00000
      500000.00000
      END

Even though the input projection is defined in the cover, when passing a projection file on the commandline, PROJECT *does not verify the external INPUT description is correct* And, it won't work without the external description.

This is an error waiting to happen since there is no guarantee the projection as written in the prj text file matches the projection as defined internally in the cover. And then there's the headache of managing N-dozen prj1_to_prj2 projection files.

 

The Workaround

As it turns out there is a way to force PROJECT to think it is running interactively, thus using the defined projection, plus using an external projection file for automation:

&sys arc project cover incov outcov \path\albers.prj

where "albers.prj" looks like:

   /* the '&if' lines allows this prj file to be used automatically with
   /* with PROJECT and PROJECTDEFINE. The semicolon at the beginning of
   /* the line is important. To use this file from Arc:
   /* "&sys arc project <grid|cov> <cov_in> <cov_out> <%.prj%\albers.prj"
   /* "&sys arc projectdefine <grid|cov> <cov> <%.prj%\albers.prj"
   ;&if [locase[show program]] = project &then; OUTPUT;
      Projection    ALBERS
      Datum         NAD83
      Zunits        NO
      Units         METERS
      Spheroid      GRS1980
      Xshift        0.0000000000
      Yshift        0.0000000000
         Parameters
       61 40  0.000 /* 1st standard parallel
       68  0  0.000 /* 2nd standard parallel
      -132 30  0.000 /* central meridian
       59  0  0.000 /* latitude of projection's origin
      500000.00000 /* false easting (meters)
      500000.00000 /* false northing (meters)
   ;&if [locase[show program]] = project &then; END;
</cov></cov_out></cov_in>

You don't really need the &if lines, you can just slap the OUTPUT and END lines in there anyway, but using &if gets you one less error message.

There is a speed penalty to pay since you are invoking a shell within a shell with a shell, but it's pretty cheap compared to the added security and reliability.

%.prj% points to a network shared drive which all users can read (x:\arcutils\prj)

 

PostScript: the same methodology can be used to automate other interactive commands like Append:

&sys arc append outcov < list_of_covers.txt

-- MattWilkie - 05 Feb 2001

 

---

smart-proj.aml: AML which implements the approach discussed here.

To use:

• create a global variable .PRJ which points to where your projection files are stored, e.g. z:\arcutils\prj .Have this var set everytime you start Arc (ESRI:11653).
• put your smart projection definition files in .PRJ\smart\ (without any extension)

The command

   Arc: &r smart-proj * albers

will project all of the covers in the current directory to Albers. Output is in a workspace called Albers under the current workspace.

The script is noisier than I'd like, ouputting so many messages to the screen that it's hard to see what's going on. It works well though and that's what matters to me.

 

-- MattWilkie - 20 Apr 2004

 

 

 

 

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TopicCategory	HowTo

I	Attachment	Action	Size	Date	Who	Comment
aml	smart-proj.aml	manage	3.3 K	2004-04-20 - 16:34	MattWilkie	AML which implements the approach discussed here