Chapter 21 Cameras, Walkthroughs, and Flybys 563 Copyright Goodheart-Willcox Co., Inc. Camera Area The camera can be linked to a path or a point. To select a path, pick the Path radio button and then pick the “select” button next to the radio buttons. The dialog box is temporarily closed for you to select the path in the drawing. The path may be a line, arc, circle, ellipse, elliptical arc, polyline, 3D polyline, spline, or helix, but it must be drawn before the ANIPATH command is used. Splines are nice for motion paths because they are smooth and have gradual curves. The camera moves from the fi rst point on the path to the last point on the path, so create paths with this in mind. Once you select the path, you will be prompted to specify a name for the path. If you do not name it, AutoCAD will give it a default, sequential name, such as Path1, Path2, etc. To select a stationary point, pick the Point radio button. Then, pick the “select” button next to the radio buttons. When the dialog box is hidden, specify the location in the drawing. You can use object snaps or enter coordinates. It may be a good idea to have a point drawn and use object snaps to select the point. As when selecting a path, once you select the point, you will be prompted to specify a name for the point. The camera must be linked to either a path or a point. If neither is selected, the command cannot be completed. If you want the camera to remain stationary as the target moves, select the Point radio button and then pick the stationary point in the drawing. Once a point or path has been selected, it is added to the drop-down list. All named motion paths and selected motion points in the drawing appear in this list. Instead of using the “select” button, you can select the path or point in this drop-down list. Target Area The target is the location where the camera points. Like the camera, the target can be linked to a point or a path. To link the target to a path, select the Path radio button. Then, pick the “select” button and select the path in the drawing. If the camera is linked to a point, the target must be linked to a path. If the camera is set to follow a path, then you actually have three choices for the target. It can be linked to a path, point, or nothing. To link the target to a point, pick the Point radio button. Then, pick the “select” button to select the point in the drawing. The None option, which is selected in the drop-down list, means that the camera will look straight ahead down the path as it moves. Animation Settings Area Most of the settings in the Animation settings area have the same effect as the corre- sponding settings in the Animation Settings dialog box discussed earlier. However, there are four settings unique to the Motion Path Animation dialog box. The Number of frames: text box is used to set the total number of frames in the animation. Remember, a computer has a playback rate of 30 fps. Therefore, if the frame rate is set to 30, set the number of frames to 450 to create an animation that is 15 seconds long (30 × 15 = 450). The value in the Duration (seconds): text box is the total time of the animation. This value is automatically calculated based on the frame rate and number of frames. However, you can enter a duration value. Doing so will automatically change the number of frames based on the frame rate. By default, the Corner deceleration check box is checked. This slows down the movement of the camera and target as they reach corners and curves on the path. If this is unchecked, the camera and target move at the same speed along the entire path, creating very jerky motion on curves and at corners. It is natural to decelerate on curves. Checking the Reverse check box simply switches the starting and ending points of the animation. If the camera (or target) travels from the fi rst endpoint to the second endpoint, checking this check box makes the camera (or target) travel from the second endpoint to the fi rst.