|VCS Example: Defining a Logical Mask|
This example shows how to use the VCS Logical Mask function to mask out node points. By default, the absolute value of any data value greater than or equal to 10**20 is masked out in VCS. Beginning with Version 2.6, the masking option has been extended so that a logical `and' operation is performed on the assigned mask value M and 10**20, allowing masking when specified criteria are satisfied. These criteria may be defined by 5 operators: greater than (>), less than (<), equal (=), greater than or equal (>=), and less than or equal (<=).
Step 1: Displaying Data with the Isofill Graphics Method
Access the blue Isofill Graphics Method Panel (via Main Menu: `Primary' -> `Graphics Table' -> `Isofill'). Note, VCS does not allow the modification of any `default' attribute sets. Therefore, move the pointer over the Isofill `default' attribute set name and click the middle mouse button. Next move the pointer over the Isofill menu button, and press and hold the left mouse button. Then move over the `Copy' item and release the left mouse button--a popup window will appear. Enter a new Isofill attribute set name (e.g., `example'), and select the `Save' button. The `example' attribute set name will appear in the blue Isofill Graphics Method Panel. This is the new `Isofill' attribute set that will be utilized in this example.
Use this newly created `Isofill' attribute set name and the Template Panel's `default' attribute set name in the chosen picture descriptor form located in Page Description Panel. Move the pointer over the example.nc file in the Data Selection Panel, and click the left mouse button. Then move the pointer over the `psl' variable in this Panel's `Variables' scroll window and double-click the left mouse button. The data set attribute name `psl (3D)' will appear in the red Data Panel above.
In order to display the data, move the pointer over `psl (3D)' in the red Data Panel, and click the middle mouse button. Then move the pointer to the chosen red input text window in the picture descriptor form and click the middle mouse button. This action will plot the `psl (3D)' data with the Isofill graphics method on the VCS Canvas. (See the Example on Modifying Isofill Attributes).
Step 2: Accessing the Data Editor Panel in Defined Mode
Move the pointer over the displayed data attribute set name (i.e., `psl (3D)') in the red Data Panel and click the left mouse button. The Data Editor Panel '(A_psl)' will appear below. Move the pointer over the `Defined' toggle button (at the top of the Data Editor Panel) and click the left mouse button--the defined data attribute set will be shown.
See also the Example on Modifying Data.
Step 3: Creating a Logical Mask Function
In the yellow 'LogicalMask' input text window, enter `psl>1015'. Then select the red `Apply' button (located in the upper right corner of the Data Editor Panel) to view changes. The `psl' values less than or equal to 1015 are masked out and the plot is redrawn on the VCS Canvas.