The Analysis > Grids operation

Grids operation is used to subtract 2 grids to get a third one containing the result of the operation.

This interface is accessed from the ribbon Simu - Renderings, by clicking on the button in the group Renderings.

If there is no data set containing the grids a warning message appears. Only overlays containing grids are listed.

Grids operation

Overlays

Note that grids or polygons can be used for operations.

If an overlay containing polygons is selected, it is necessary to specify which attributes has to be used for the operation. For a grid, the pixel values are read for the operation.

•A: first overlay. For a grid, its resolution is displayed.

•B: second overlay. For a grid, its resolution is displayed.

Operation

•√a²+b²: RMS (Root Mean Square) addition of the overlays "A" and "B".

•√a²-b²: RMS subtraction of the overlays "A" and "B".

•a+b: Mathematical addition of the overlays "A" and "B".

•a-b: Mathematical subtraction of the overlays "A" and "B"..

Theme

There are three ways to create a theme:

•Automatic: created automatically according to min. and max. values calculated. No user intervention required.

•Create later: the theme interface appears at the end of processing and offers a theme by default.

•Existing: the user chooses an existing theme from the list. The button can be used to delete a theme. This button cannot be accessed if the current theme is a default theme. The button can be used to edit a theme or simply to view a them in the case of a default theme (see Theme parameters).

Results

•Resolution: corresponds to the size that a pixel represents. A resolution of 5m means that 1 pixel = 5 meters.

•File name result: file name created, containing all result grids in the 'GridOperation' directory. This directory is located in the data directory and will be created if it does not already exist.