INDEX

### NVIZ - Basic Animation

Use the Animation panel to create simple fly-bys of surfaces.

### Animation Panel

step, run, Key Frames: The Frames slider may be thought of as a time line representing the path. When a path has been loaded, clicking on run will move the viewer down the path, redrawing the wire frame surface at each path step. The user may cancel a running animation at any time by clicking on the stop button. The Key Frames slider shows the progression of the animation. Use the step arrows to step forward or backward one frame at a time, or move the Key Frames slider to the desired point in the animation. The number to the right of the step arrows is the frame number being displayed.

total frames: The value in this type-in box is the total number of frames in the animation. When a vector file is first loaded, the number of points in the file (up to 1000) will be the number of frames. Typically, to produce smooth animations, the user should use a vector file with 10 - 50 points, then change total frames to 100 or more, depending on the length of the animation desired. Requesting an excessive number of frames (i.e., 500,000) may cause memory problems.

show path: Toggling this button ON will cause the path to be drawn each time a new frame is drawn. The color and thickness of the path line may be changed using adjustments on the Vectors pop up panel. Showing the path can be useful while previewing and adjusting the path.

show vect: Toggling this button ON will cause vectors to be drawn each time a new frame is drawn, if a vector file has been loaded. (see also Vect...).

spline, linear, tension: These controls affect the interpolation method used when the value of total frames is different than the number of points in the original vector file used as the path. The points from the vector file are always used as control points from which the positioning information for the total number of requested frames is derived. If spline interpolation is selected, the user may adjust spline tension (how much slack there is in the path) using the tension slider. Toggling show path ON prior to adjusting tension allows the user to judge how much tension to use for a smoother path.

run and save images: Prompts user in the GRASS window for a prefix to be used to name a series of rgb format image files, one for each frame. The animation is then run from the beginning, with each frame being fully rendered using the current display type and resolution (see Control panel). If show vect is toggled ON, the vector file is also drawn, then the finished frame is written to an rgb file. If files already exist with the same name, they are overwritten. You may cancel run and save images at any time by selecting stop This entire process may take several hours of computer time for a 100 frame animation of a complex surface, but requires no further intervention from the user. The finished rendered animation files can be played back using SGI's movie program if it is a very short animation or you can capture the images on video (Also see Img Dump).