Chapter 21 Cameras, Walkthroughs, and Flybys 551 Copyright Goodheart-Willcox Co., Inc. in the active viewport. The view is also listed under the Model Views branch in the View Manager dialog box. It can be made current by selecting the view, picking the Set Current button, and then picking the OK button. PROFESSIONAL TIP PROFESSIONAL TIP In addition to the camera name, many other camera properties can be changed in the Properties palette. The camera and target locations can be changed, the lens focal length and fi eld of view can be adjusted, and the clipping planes can be modifi ed. Also, you can change the roll angle, which is the rotation about a line from the camera to the target, and set the camera glyph to plot. Camera System Variables The CAMERADISPLAY system variable controls the visibility of camera glyphs. When set to 1, camera glyphs are displayed. When set to 0, camera glyphs are not displayed. Creating a camera automatically sets the variable to 1. The Camera Display button in the Camera panel on the Visualize tab of the ribbon toggles the display of camera glyphs off and on. When creating a camera, if you pick the camera and target locations without using object snaps, you may assume that the camera and target are located on the XY plane (Z coordinate of 0) of the current UCS. This may or may not be true. The CAMERAHEIGHT system variable determines the default height of the camera if a Z coordinate is not provided. It is a good idea to set this variable to a typical eye height before placing cameras. There is no corresponding system variable for the target because the target is usually placed by snapping to an object of interest. If X and Y coordinates are entered for the target location, but a Z coordinate is not provided, the Z value is automatically 0. If a camera was previously created in the drawing session and the Height option was used, that height value becomes the default camera height. Cameras Tool Palette The Cameras tool palette provides a quick way to add a camera, but the default tools do not allow for the options described earlier. The Normal Camera tool creates a camera with a 50 mm focal length. This camera simulates normal human vision. The Wide-angle Camera tool creates a camera with a 35 mm focal length. This type of view is commonly used for scenery or interior views where it is important to show as much as possible with minimal distortion. The Extreme Wide-angle Camera tool creates a camera with a 6 mm focal length. This camera produces a fi sh-eye view, which is very distorted and mainly useful for special effects. Changing the Camera View Once the camera is placed, it is easy to manipulate. If you select a camera, the Camera Preview window is displayed by default. This window shows the view through the camera, Figure 21-2. The view in the window can be displayed in any of the 3D visual styles or any named visual style. Select the visual style in the drop-down list in the window. If the Display this window when editing a camera check box at the bottom of the window is unchecked, the window is not displayed the next time a camera is selected. The next time the drawing is opened, this setting is restored (checked). When a camera is selected, grips are displayed. Refer to Figure 21-1. If you hover the cursor over a grip, a tooltip appears indicating what the grip will alter. Picking the base grip on the camera allows you to reposition the camera in the scene. If the Camera Preview window is open, watch the preview as you move the camera to help CAMERADISPLAY Ribbon Visualize Camera Camera Display Type CAMERADISPLAY