What are surface brightness and lights?

The surface of the 3D surface plot is illuminated in areas so that you can better see surface features. You can change the brightness of the surface, and the number and position of up to three surface lights.

Change the surface brightness

You can change the surface brightness on a 3D surface plot.

  1. Double-click the surface and click the Lights tab.
  2. In Brightness, enter a number between 0 (darkest) and 100 (brightest).
    Brightness = 10
    Brightness = 90
  3. Click OK.

Rotate the surface lights

Use the 3D Graph Tools toolbar to rotate the lights on a 3D surface plot.

  1. Click the 3D surface plot or 3D wireframe plot to activate it.
  2. If the 3D Graph Tools toolbar is not visible, choose Tools > Toolbars > 3D Graph Tools.
  3. Use the following items on the 3D Graph Tools toolbar to rotate the lights. Click each button one time to rotate the lights in small increments. Click and hold a button for continuous rotation.
    Toolbar item Action
    Rotate the lights clockwise or counterclockwise about the x-axis.
    Rotate the lights clockwise or counterclockwise about the y-axis.
    Rotate the lights clockwise or counterclockwise about the z-axis.
    Return the lights to their original positions. Also returns other surface lighting options, except brightness, to their original settings.

Change the position of the surface lights by entering coordinates

The relative position is the position of the light relative to the center of the graph space.

  1. Double-click the surface and click the Lights tab.
  2. Under Relative Position, enter the coordinates and color for up to three lights. The x-, y-, and z- coordinates for the positions of lights on a 3D surface plot are expressed relative to the center of the data region, which is coordinate 0 0 0. Coordinate units are designed to be consistent between x, y, and z. Thus, they are not related to the data measurement units. See the following section for more information.
  3. Click OK.

Examples of surface light coordinates

The x-, y-, and z- coordinates for the positions of lights on a 3D surface plot are expressed relative to the center of the data region, which is coordinate 0 0 0. Coordinate units are designed to be consistent between x, y, and z, and are thus not related to the data measurement units.

Default light position

The red dot above the graph represents Light 1 in its default position. The blue dot below the graph represents Light 2 in its default position.

The coordinates for these positions are:

Light X Y Z
1 0 1 1
2 0 0 -1

Light 1 is in the center of the graph space with respect to the x-axis (x = 0), but one unit in the positive direction with respect to both the y- and z-axes (y = 1 and z = 1). This gives it the appearance of being above and somewhat behind and to the right of the graph.

Light 2 is directly below the graph space, centered with respect to the x- and y-axes (x = 0 and y = 0), but one unit in the negative z direction (z = -1).

Light is centered

X and Y for Light 1 have been set to zero, so it is centered directly above the graph. Notice that the red light illuminates more of the nearer face of the graph than in the previous figure.

The coordinates for these positions are:

Light X Y Z
1 0 0 1
2 0 0 -1

Light is increased

Z for Light 1 has increased to 2, so it is higher above the graph. Notice this has the effect of spreading the red illumination across more of the surface.

The coordinates for these positions are:

Light X Y Z
1 0 0 2
2 0 0 -1

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