Setting the Viewpoint with Azimuth and Elevation :: Defining the View (3-D Visualization)

3-D Visualization

Setting the Viewpoint with Azimuth and Elevation

MATLAB enables you to control the orientation of the graphics displayed in an axes. You can specify the viewpoint, view target, orientation, and extent of the view displayed in a figure window. These viewing characteristics are controlled by a set of graphics properties. You can specify values for these properties directly or you can use the view command and rely on MATLAB automatic property selection to define a reasonable view.

Azimuth and Elevation

The view command specifies the viewpoint by defining azimuth and elevation with respect to the axis origin. Azimuth is a polar angle in the x-y plane, with positive angles indicating counterclockwise rotation of the viewpoint. Elevation is the angle above (positive angle) or below (negative angle) the x-y plane.

This diagram illustrates the coordinate system. The arrows indicate positive directions.

Default 2-D and 3-D Views

MATLAB automatically selects a viewpoint that is determined by whether the plot is 2-D or 3-D:

For 2-D plots, the default is azimuth = 0° and elevation = 90°.
For 3-D plots, the default is azimuth = -37.5° and elevation = 30°.

Examples of Views Specified with Azimuth and Elevation

For example, these statements create a 3-D surface plot and display it in the default 3-D view.

[X,Y] = meshgrid([-2:.25:2]);
Z = X.*exp(-X.^2 -Y.^2);
surf(X,Y,Z)

The statement

```
view([180 0])
```

sets the viewpoint so you are looking in the negative y-direction with your eye at the z = 0 elevation.

You can move the viewpoint to a location below the axis origin using a negative elevation.

```
view([-37.5 -30])
```

Limitations of Azimuth and Elevation

Specifying the viewpoint in terms of azimuth and elevation is conceptually simple, but it has limitations. It does not allow you to specify the actual position of the viewpoint, just its direction, and the z-axis is always pointing up. It does not allow you to zoom in and out on the scene or perform arbitrary rotations and translations.

MATLAB camera graphics provides greater control than the simple adjustments allowed with azimuth and elevation. The following sections discuss how to use camera properties to control the view.

Viewing Overview Defining Scenes with Camera Graphics