Topic:
How to do multiple grid operations when there is a units mismatch between grids.

Description:
The below is of interest when comparing two approaches to depth conversion for a
grid. For the first conversion the time attribute is squared then scaled. For
the other only a scalar was aplied.
To find the difference between the two subtract one from another using the
Gridding > Grid Operations > Multiple option.
  
However, when you click either Apply or OK, two windows pop-up in succession:

IESX information:
Invalid Property 1 definition

Clicking OK pops-up the second window:

IESX Error
Specified property code is invalid

The multiple grid operation is not performed.

Note that the units (property code) for the scaled grid is Time while the units
(property code) for the squared grid is Unknown.

How can the difference between these two grids be found?  

Solution:
1. Basemap > Gridding > Grid Operations > Multiple
   Click the First Grid tab, select the surface name that contains the "squared"
   grid in the left scrolled area, and select the squared grid name in the right
   scrolled area.  

2. Click the Second Grid tab, select the surface name that contains the
   "scaled" grid in the left scrolled area, and select the scaled grid name in
   the right scrolled area.  

3. Click the downward pointing triangle to the right of the Grid 1 (Units) field
   and select ms from the scrolled list.  The Grid 1 (Property) field becomes
   active.

4. Click the downward pointing triangle to the right of the Grid 1 (Property)
   field and scroll down to and select Time.

5. Set the (Operation) toggle to Minus.  The Property field for the output grid
   (lower right hand corner of window) becomes active.

6. Click the downward pointing triangle to the right of the output grid
   Property field and scroll down to and select Time.

7. Set the other output grid parameters as desired and click the OK button at
   the bottom of the Basemap Plus Multiple Grid Operations window.  

8. The temporary grid that is created has the Property Time and may be saved as
   usual (Gridding > Save As)

==============================================================================

If you wish to change the units of the ``squared'' grid from Unknown to ms
you have several options outlined as separate methods below:


Method 1 - Using Basemap Plus to change grid units.
--------

1. Open the Basemap Plus Multiple Grid Operations window 
   (Gridding->Grid Operations->Multiple...)

2. Select the ``squared'' grid as both the first and second grids.

3. Set the (Operation) toggle to Plus.

4. Set the Grid 2 (Scale) field to 0.
 
5. Set the (Units) field for both grids to ms.

6. Set the (Property) field for both input grids and the output grid to Time.

7. Click the OK button to output the Temporary Grid (same as input grid but 
   with units changed).

8. Save the Temporary Grid to a permanent grid name (Gridding->Save As...).


Method 2 - Using (GeoFrame) Project Grid Data Manager to change grid units.
--------

1. Open the Project Grid Data Manager (Data Management Catalog->Grids) and 
   click the Grids... button.

2. In the Select Grids for Display window, select (highlight) the grid name 
   whose units you wish to change and click OK.  This brings the grid into 
   the Project Grid Data Manager scrolled area.

3. In the Project Grid Data Manager select (MB1) that grid in the scrolled 
   area and click the blue "i" icon which opens the Grid Editor window.

4. In the Grid Editor window, click the General Attribute Editor... button 
   which opens the General Attribute Editor window.

5. In the General Attribute Editor, click the Attributes... button which 
   opens the Grid Attributes window.

6. In the Grid Attributes window, scroll down to and toggle on the 
   Property_Code and Unit attributes and click OK.  This puts those two 
   attributes into the scrolled list in the General Attribute Editor.

7. Back in the General Attribute Editor, enter the string Time in the field 
   next to the label Property Code and enter the string "ms" in the field next 
   to the label Unit (Storage Unit).  Now click the OK button.

8. Back in the Grid Editor Window, click the Cancel button. You will have 
   noted that the Value Domain and Grid Units fields have been set to the 
   values Time and ms respectively.

9. Back in the Project Grid Data Manager, Click the OK btton.  You will have 
   noted that the Property Code value is now listed as Time.

You will be able to perform the multiple grid operations without reposting 
the grid with the changed units.  However, you will have to repost the grid 
in the Basemap in order to see the color scale annotation reflect the changed 
units (Post->Interpretation->Grid - cut the grid from the list, add it back in, 
and click OK).


Method 3 - Using Basemap Plus and IESX Datamanager to change grid units.
--------

1. In Basemap, regenerate the ``squared '' grid and save it to a new 
   surface name.  

2. Open the Surface transfer window (IESX Datamanager->Surface Transfer...)

3. Select (highlight) the survey and new surface name.

4. Enter Z in the Name field below the Attribute scrolled area.

5. Select (highlight) the grid name in the Grid scrolled area.

6. Click (MB1) the Add to Transfer list button.

7. Click (MB1) the Transfer button. The grid values are copied to the 
   Z attribute of the horizon.

8. In Basemap, grid the new horizon (save as desired) and perform the 
   desired multiple grid operation.



Last Modified on: 14-SEP-00