Surface Tool How to

One way to modify the appearance of the surface plot in the Surface Tool is to change the surface attributes. Attributes include mesh type, color, skirt, shading, and light source.

To change the surface attributes, follow these steps:

1. Choose Attributes=>Surface Attributes to bring up the Surface Attributes dialog box.

2. Make your selections in the dialog box. Click the Help button for detailed information on the dialog box features.

3. Click OK or Apply to apply the new attributes to the surface plot.

Changing the Surface Colors

To change the color used for the upper and lower portions of a surface in the Surface Tool, follow these steps:

1. Choose Attributes=>Surface Attributes to bring up the Surface Attributes dialog box.

2. Click MB1 on the Upper Color or Lower Color button to bring up the Color dialog box. Use this dialog box to choose a color. The selected color is reflected in the related color square in the Surface Attributes dialog box.

3. In the Surface Attributes dialog box, click OK or Apply to apply the color change to the surface.

Shading a Surface

To produce a shaded surface in the Surface Tool, you can specify a shading algorithm, or you can drape an image over a surface to produce shading effects.

Specifying a Shading Algorithm

The following algorithms can be used to shade surface data: None (no shading), Gouraud, Elevation, and From Variable.

To specify a shading algorithm, follow these steps:

1. Choose Attributes=>Surface Attributes to bring up the Surface Attributes dialog box.

2. Click MB1 on the Shading list button and select the algorithm you prefer.

3. Click OK or Apply in the Surface Attributes dialog box to apply the shading to the surface.

Specifying a Shade Variable

A shade variable is the name of the variable that contains the shading information.

To specify a shade variable, follow these steps:

1. Choose Attributes=>Surface Attributes to bring up the Surface Attributes dialog box.

2. Click MB1 on the Shading list button and select the From Variable function.

3. Click MB1 in the Shade Variable text field, then type the name of the shade variable you want to use.

4. Click OK or Apply in the Surface Attributes dialog box to apply the shading to the surface.

note	Shading variables are converted to 8-bit grayscale images before being displayed.

Adding a Skirt to a Surface

A skirt helps establish a frame of reference between the surface and the x, y, and z-axes.

To add a skirt to a Surface Tool surface, follow these steps:

1. Choose Attributes=>Surface Attributes to bring up the Surface Attributes dialog box.

2. Click MB1 on the Skirt check box to select it.

3. Click MB1 in the Skirt Bottom text field, then type the value for the height of the skirt.

4. Click OK or Apply in the Surface Attributes dialog box to apply the skirt to the surface.

Displaying Data in a Surface Tool

The default is to display the data as a regularly gridded fishnet (mesh) surface, looking down at the top of the surface, and using no skirt.

Before you can display a variable in a Surface Tool, the variable must already exist on the $MAIN$ level of PV-WAVE.

Use any of the following methods to display a variable in a Surface Tool:

Open a Surface Tool from the Navigator when one or more variables are on the variable selection list. The first variable on the variable selection list is plotted when the Surface Tool is opened (assuming the variable is of an appropriate type and dimension). See Displaying a Variable in a VDA Tool Started from the Navigator for more information.

Import a variable. To do this, use the File=>Import Variable(s).

Export selected data from another VDA Tool using the File=>Export Selected Data function in the source VDA Tool.

Supply a variable name as a parameter to the Surface Tool command. You can import a single 2D or variable (z) or provide additional x and y variables containing the x and y coordinates of the gridded z data. The function also accepts 8 or 24-bit image data. See Using Multiple Surface Variables for more information. For example:

WAVE> WzIPSurface, snow_data

where snow_data is a variable on the $MAIN$ level of PV-WAVE.

See Also

Using Multiple Surface Variables

Using Multiple Variables to Create the Surface

Occasionally, you may need to provide coordinate data for a surface view in two separate variables. If you choose to provide x and y variables, they are used by the Surface Tool to determine the x and y coordinates of the gridded z data. The Surface Tool generates x and y tick labels using the range of the x and y variables.

Each of the allowed Surface Tool variables is discussed below:

z—A 2D array or image containing the values that make up the surface. If you supply x and y variables, the surface is plotted using the coordinates specified by the values in the x and y variables. If you do not supply x and y variables, the surface is generated using the array indices of each element of the Surface Data variable.

x—(optional) A vector or 2D array specifying the x coordinates for the surface.

If x is a vector, each element of x specifies the x coordinate for a column of z. For example, x(0) specifies the x coordinate for z(0,*) (i.e., all elements in the first column of z).

If x is a 2D array, each element of x specifies the x coordinate of the corresponding point in z. For example, x(5,5) specifies the x coordinate for z(5,5).

y—(optional) A vector or 2D array specifying the y coordinates for the surface.

If y is a vector, each element of y specifies the y coordinate for a column of z. For example, y(0) specifies the y coordinate for z(*,0) (i.e., all elements in the first row of z).

If y is a 2D array, each element of y specifies the y coordinate of the corresponding point in z. For example, y(9,9) specifies the y coordinate for z(9,9).

Rotating a Surface

Two sliders in the Surface Tool’s control area indicate the amount of rotation in the x and z directions (a full revolution is 360 degrees).

By adjusting the two sliders, you can effectively change your eye-point.

To modify the rotation using the sliders, follow this step:

1. Click MB1 or MB2 on a slider and drag the slider left or right. The change is applied immediately as the slider moves.

To modify the rotation using the text fields next to the sliders, follow these steps:

1. Click MB1 in the text field.

2. Enter a new value.

3. Press <Return>. The new value is applied to the slider and to the surface.

By default, the surface rotation is:

x axis 30 degrees
z axis 30 degrees

note	If Auto Redraw is selected (the default) when you choose the rotation value, the rotation is immediately applied to the surface. If Auto Redraw has been disabled, you can use the Redraw button from the button bar to apply the rotation.

Rescaling the Surface

Often times image variables are so large that normal visualization techniques become time consuming, or so small that they are difficult to analyze visually. One way of effectively dealing with this is to use the Zoom feature located in the controls area of the Surface Tool window.

The Zoom slider allows you to display the surface at a smaller or larger size. The zoom function works as follows:

Press and drag MB1 on the Zoom slider.

Enter a scale value in the text entry box to the right of the slider.

The scale is between 0.1 and 2.0. The default value is 0.6.

If Auto Redraw is selected (the default) when you choose the zoom factor, the zoom is immediately applied to the surface. If Auto Redraw has been disabled, use the Redraw button from the button bar to apply the zoom.

note	The Zoom value is always referenced to the original surface size.

Button Bar Buttons

The Button Bar contains functions for editing graphical elements, selecting, and adding graphical elements.

note	Position the pointer over a button to see its name printed just below the Button Bar. If a button is inactivated, no name will appear.

	Redraw—Redraws the current view and updates the view with any data changes.
	Cut—Cuts the selected graphical elements. A cut object can be pasted into the same graphics area or into the graphics area of another VDA Tool.
	Copy—Copies the selected graphical elements to a clipboard. A copied object can be pasted into the same graphics area or into the graphics area of another VDA Tool.
	Paste—Pastes the contents of the clipboard in the graphics area of a VDA Tool.
	Delete—Removes the selected graphical elements from the plot window and redraws the view. When a graphical element is deleted, it is not added to the clipboard. Therefore, you cannot paste or in any other way restore an item that has been deleted.
	Object Selection—Lets you select graphical elements in the plot using the mouse. Graphics elements include text, lines, rectangles, legends, and axes. Selected graphics elements can be cut, copied, pasted, deleted, or grouped.
	Create Text Object—Add words and phrases to accentuate important trends and differentiate features of the view. Use MB1 to pick a starting point for the text, then enter the text. Press <Return> when you are finished entering text.
	Create Line Object—Add a line to the display area to emphasize a particular value or to visually connect text to some feature of interest elsewhere in the view. Press and drag MB1 to define the line. Press and drag <Control>-MB1 to constrain the line to be horizontal or vertical.
	Create Box Object—Add a box to the display area to enclose a region of special interest. Press and drag MB1 to define the corners of the rectangle. Press and drag <Control>-MB1 to create a square.
	Create Ellipse Object—Add an ellipse to the display area to enclose a region of special interest. Press and drag MB1 to define the bounding box of the ellipse. Press and drag <Control>-MB1 to create a circle.