When a molecular system moves through a trajectory, the part you want to inspect can drift away from the center of the view. You may find yourself repeatedly adjusting the camera just to keep a molecule, domain, or other selected group visible. In SAMSON, the Follow atoms animation can handle that camera movement for you.
The animation follows the atoms selected when you create it. As those atoms move, the camera target follows their geometric center, and the camera position moves with it. The direction and distance between the camera target and camera position remain constant, so the view travels with the selected atoms rather than staying behind at its original location.
Set up the view before adding the animation
Start by selecting the atoms you want to follow. Selection matters: the animation is based on the atoms selected at creation, so check that the intended group—not the whole system or an unintended subset—is selected.
Next, orient the camera as you want the scene to appear. This initial view establishes the camera position used at the animation’s start frame. If the subject is too close, too far away, or poorly angled, adjust the view before adding the effect. The follow animation moves the camera along with the selected atoms; it does not replace the initial composition you choose.
In the Animator’s Track view, choose the frame where the camera should begin following. Then double-click Follow atoms in the Animator’s Animation panel. Set the animation’s end frame to cover the part of the trajectory you want to show. You can move the start and end frames later if the timing needs adjustment.
What moves—and what stays consistent
Between the two keyframes, the camera target is positioned at the geometric center of the selected atoms. The camera itself moves as the atoms move, preserving the vector between the target and camera position. In practical terms, this keeps the viewing distance and relative camera direction consistent while the selected group travels through the system.
This is useful for making a trajectory easier to inspect or present when the region of interest changes position. It can also reduce distracting manual camera corrections during playback. Keep in mind that the effect follows the selected group’s center: it does not describe every atom’s motion individually, and the camera’s position is adjusted according to the selected atoms’ movement.
Fine-tune the camera behavior
By default, camera animations apply to the active camera. If your scene uses another camera, inspect the animation and review Apply to active camera. The animation’s target point is based on the active camera’s current target position, which is generally the center of the view.
The Keep camera upwards option affects how camera positioning behaves in relation to whether the grid is on or off. If the camera’s orientation behaves differently than expected, inspect the animation and check this setting alongside the grid state.
You can adjust camera position using the animation controllers. The target, however, remains at the geometric center of the specified atoms. This distinction is useful when refining the viewpoint: adjust the camera position to change how the moving group is viewed, while relying on the animation to keep the group’s center as the target.
For the full procedure and animation properties, see the Follow atoms documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.