Grid Properties

Use the Grid and Image > Properties menu option (GRIDSTAT GX) to report and modify information about a grid, including simple statistical information and coordinate system information.

Grid Properties dialog options

The Grid Properties dialog is designed as a "wizard" that presents information depending on what you want to see or do.

Grid Properties - select a file

The first dialog enables you to select the grid file that you are interested in:

Grid	Select the grid file to report.
Next>	Select this button to display basic grid information together with options to see other information or to change certain information. The Grid Properties dialog will be displayed.

Grid Properties - grid information

All basic information about the grid is reported. The information displayed in this dialog is used to locate the grid in a real coordinate system. To make any changes to these parameters, click the Modify button.

Grid	Displays the name of the grid
Grid element type	Displays the grid element type (e.g., FLOAT, SHORT, DOUBLE).
Grid points in X direction	Displays the number of grid points in X direction.
Grid points in Y direction	Displays the number of grid points in Y direction.
X point separation	The separation between grid points in the grid X direction.
Y point separation	The separation between grid points in the grid Y direction
Grid row orientation	The grid row orientation (e.g., bottom left to right (KX=1)). For more information see Grids and Images.
X location of the bottom left point	The X location of the bottom left grid point in the coordinate system.
Y location of the bottom left point	The Y location of the bottom left grid point in the coordinate system.
X location of top right point	The X location of the top right grid point in the coordinate system.
Y location of top right point	The Y location of the top right grid point in the coordinate system.
Grid rotation angle	The angle of the grid in degrees counter-clockwise from the map coordinate system. Normally, this angle is 0.
Coordinate system	This displays the map coordinate system projection of the grid, if any. Click the Modify and then the CoordSys button to modify the coordinate system projection.
Coordinate system units	This displays the length units of the coordinate system. The grid origin and point separations are in these units. Click the Modify and then the CoordSys button to modify the coordinate system projection and units.
Compression ratio	The compression ratio of the grid file.
<Back	Select this button to return to the Grid Properties - select a file dialog.
Stats	Displays the Grid Statistics dialog, which presents basic statistical information about the data in the grid. You also have the opportunity to, re-calculate the grid, view a histogram of the data distribution, and view the removed trend coefficients, if any, from the Grid Statistics dialog.
Modify	Displays the Modify Grid Properties dialog, which enables you to change grid location and coordinate system projection information about the grid. See "Modify grid information" below.
Exit	Select this button to exit the grid statistics wizard.
	Select this button to retrieve Application Help information.

Grid Statistics

All basic statistical information about the grid is reported. The information labels are self-explanatory. The following table describes the function of each of the buttons.

<Back	Select this button to return to the Grid Properties - grid information dialog.
Re-Calc	Select this button to re-calculate the grid. For more information, see the [Re-Calc] Note below.
Histogram	Select this button to View a Histogram of the grid.
Trend	If a trend has been removed from the grid, this button will display the removed trend coefficients.
Cancel	Select this button to cancel the Grid Properties wizard.

The Re-Calc button recalculates the statistics by re-auditing the entire grid, one element at a time. This process may slightly change the reported statistics (in the 5^th or 6^th significant digit) because this calculation differs from the default method, which is to read values from the grid header, or from the ".gi" or grid information file created by Oasis montaj to contain extra information about the grid. This change does not mean that data in the grid has changed. The grid header often contains scaled values, especially if it stores values as integers, and this is the source of the discrepancy.

Modify Grid Properties

The information displayed in this dialog is used to locate the grid in a real coordinate system. The information labels are self-explanatory. The following table describes the function of each of the buttons.

Changing anything in this dialog will have the effect of moving or changing the apparent size of the grid when displayed on a map.

<Back	Select this button to return to the Grid Properties - grid information dialog.
OK	Select the OK button to accept your modifications to the grid properties, and return you to the Grid Properties - grid information dialog.
CoordSys	The CoordSys button will run the Coordinate System wizard, which enables you to view and modify the projection information. For more information about the Coordinate System wizard, click the button on the Coordinate System dialog.
Cancel	Select this button to cancel the Grid Properties wizard.

Application Notes

This dialog will only enable you to look at and modify information about a grid. No data contained in the grid will be changed.

Use the REGRID GX to change the sampled cell size of a grid.

Use the GRIDREPJ GX to re-project a grid to a new coordinate system.

Use the WARPGRID GX to warp a grid.

Metadata

Metadata (data about data) is captured by Oasis montaj from the first time the data is touched. The metadata information, which is based on ISO 19115 standards, is stored inside the data (if supported) or as a companion XML file.

Metadata (or Properties) are any information about the data. This includes; reports, survey parameters, projection information, or basically anything related to or that describes the data itself.

Modify Grid Headers

This GX can also be used to modify certain grid information in the header, such as grid location, cell size and map projection. It can directly change the grid header.

Therefore, it is possible to change the location of the grid on the ground and lose the correct ground registration of the grid. It is also possible to make the grid unreadable by setting header parameters to unreasonable values.

Script Usage

This GX can also be run from a script to report statistics and to modify parameters. Following are the scripting parameters:

GRIDSTAT.GRID	File Name of the Input Grid.
GRIDSTAT.REPORT	The name of a file in which to place a grid information report. "stdout" will report the results to the command shell.
GRIDSTAT.RECALC	"Yes" to force recalculation of grid statistics
GRIDSTAT.MODIFY	"Yes" to change the grid parameters as follows If changing grid parameters, all parameters must be defined, and if blank, only those that are defined will be changed.
GRIDSTAT.DX	grid X point separation
GRIDSTAT.DY	grid X point separation
GRIDSTAT.X0	X location of bottom left grid point
GRIDSTAT.Y0	Y location of bottom left grid point
GRIDSTAT.ROT	rotation angle (CCW) of grid X relative to map X
GRIDSTAT.IPJ_NAME GRIDSTAT.IPJ_DATUM GRIDSTAT.IPJ_METHOD GRIDSTAT.IPJ_UNITS GRIDSTAT.IPJ_LOCALDATUM	Projection information in GXF format. \"unknown\" should be entered as the IPJ_NAME to remove a projection. Set IPJ_NAME to blank to leave projection as is. See GXF documentation for details on formatting these parameters. To set a projection from a old-style PRJ file, specify the PRJ file name as follows GRIDSTAT.IPJNAME=\"<prj_file_name>\"