When a molecular system moves through a trajectory, the part you want to study can drift toward the edge of the viewport—or out of it entirely. You can stop repeatedly repositioning the camera by using SAMSON’s Follow atoms animation. It keeps the camera moving with a selected group of atoms, helping you watch that region throughout an animation.
This is useful when the motion of one part of a larger system matters more than keeping the whole structure centered. For example, you might want to keep a moving segment visible while reviewing its trajectory. The camera target follows the geometric center of the selected atoms, while the camera position moves with it so the distance and direction between the target and camera remain constant.
Set up the view before adding the animation
Start by selecting the atoms you want to follow. Then orient the camera to establish the view you want to keep: choose the viewing direction and camera position before creating the effect. This initial view matters because the animation preserves the relationship between the camera and its target as the selected atoms move.
- Select the atoms that should remain in view.
- Orient the camera to a useful starting position.
- In the Animator’s Track view, choose the frame where the follow effect should begin.
- In the Animator’s Animation panel, double-click Follow atoms.
- Set the animation’s end frame to cover the portion of the trajectory you want to review.
You can move the start and end frames later, so you do not need to get the timing perfect on the first try. The effect uses the current camera position at the start frame. At the end, the camera has moved along with the selected atom system, preserving the camera-to-target vector.
What the camera follows—and what it does not
The target is tied to the selected atoms’ geometric center. That means the camera follows the group as a whole; it is not described as tracking a particular atom or maintaining a specific position relative to each atom. If the camera framing feels wrong, you can adjust the camera position with the animation controllers. The target, however, remains at the geometric center of the specified atoms.
This distinction can help when diagnosing an unexpected view. If the region you care about is not staying centered, check that the intended atoms were selected when you created the animation. If the region is centered but the angle or distance is not comfortable, adjust the camera position rather than expecting the target point to move independently.
Check the camera settings
By default, camera animations apply to the active camera. If you need to change this behavior, inspect the animation and modify Apply to active camera. The animation’s target point is defined using the active camera’s current target position, which is essentially the center of the current view.
Camera positioning can also behave differently depending on whether the grid is on or off. The animation’s Keep camera upwards option controls whether its behavior depends on the grid state. If the camera’s orientation is not what you expect, inspect this setting and check whether the grid is enabled.
In short: select the atoms first, compose the starting view, then add the animation. Follow atoms is most useful when you want a moving region to remain in view while retaining a consistent camera-to-target relationship.
For the full instructions and related camera-position controls, see the Follow atoms documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.