When a molecular system changes over time, the region you want to inspect can drift away from the center of the view. You may find yourself repeatedly adjusting the camera just to keep an important group of atoms visible. That can make a trajectory harder to follow—and can distract from comparing what changes in the structure.
SAMSON’s Look at atoms animation addresses this specific problem: it moves the camera’s target to follow the geometric center of selected atoms while keeping the camera position fixed. In other words, the view continues to point toward the chosen part of the system, without the camera itself traveling through space.
When this is useful
Use this animation when you want to inspect a moving part of a molecular system from a consistent camera position. For example, while animating a trajectory, you can keep directing the view toward a selected region rather than letting that region wander away from the center. Because the camera position does not change, this is different from an animation that moves the camera along with the atoms.
The target follows the geometric center of the atoms specified when the animation is created. That makes the choice of selection important: select the atoms whose collective movement should guide the view, rather than selecting the whole system by default if your attention is on just one part.
Set it up before the trajectory becomes hard to watch
- Select the atoms to track. The animation uses the atoms selected when you create it.
- Position the view. Orient the camera as you want it to be positioned. The animation uses the current camera position for its start and end frames.
- Choose a start frame. In the Animator’s Track view, set the frame where the camera behavior should begin.
- Add the effect. In the Animator’s Animation panel, double-click Look at atoms.
- Set the end frame. Adjust the animation’s duration to cover the portion of the trajectory you want to examine. You can move the start and end frames later.
Between its keyframes, the camera target moves with the selected atoms’ geometric center. The camera position stays put. This distinction is useful when you want to maintain a stable viewing location while letting the point of interest guide where the camera looks.
Two details worth checking
By default, camera animations apply to the active camera. If you need to change that behavior, inspect the animation and adjust Apply to active camera.
The Keep camera upwards option affects how the animation behaves depending on whether the grid is on or off. If the camera’s orientation behaves differently than you expect, inspect this setting and check the grid state. The camera position can also be adjusted with the animation controllers; the target, however, remains at the geometric center of the specified atoms.
A quick planning check: Are the selected atoms the ones whose movement should define the view? Is the starting camera position suitable for the full animation? Is the animation long enough to cover the frames you want to inspect? Checking these points before playback can help avoid interrupting your review to rebuild the camera setup.
For the complete instructions and details, see the Look at atoms documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.