Navigation
Customers looking at a 3D product rarely find the good bits on their own. They spin it once, see the outside, and move on. Navigation is how you take them to the parts worth seeing.
Points of interest
A marker on the model that a customer can click. Clicking it flies the camera smoothly to a view you chose.
Use them for the things you would point at if the customer were standing next to you. The dovetail joint that shows the work is real. The reinforced stitching. The port on the back nobody expects to be there.
Each marker has a position on the model and a camera view, both of which you set by dragging handles in the 3D view rather than typing coordinates. There is a preview action that flies the editor camera to the marker's view so you can judge it.
Markers can be styled, and they can be conditional, appearing only when the option they relate to is chosen. There is no point marking the walnut grain when the customer is looking at oak.
The camera motion is deliberate rather than instant, because a jump is disorienting while a move keeps people oriented.
Focals
A focal is the same camera move without a marker. Instead of waiting to be clicked, it fires by itself when a condition becomes true.
The customer switches to the engraved version, and the camera comes round to show the engraving. They choose the extended frame, and the view pulls back so they can see the whole thing.
This is one of the most effective things in the tool, because it answers a question the customer has not asked yet. They change an option, and rather than hunting for what changed, they are shown.
Focals fire on a transition rather than continuously, so a focal only moves the camera at the moment the condition becomes true, not repeatedly while it stays true. You can also trigger on a particular control changing at all, which is the way to react to something like a free text field where there is no fixed value to match on.
If several focals could fire at once, the first in the list wins, so order matters.
Focals can also reframe dynamically, adjusting to the actual size of the models they are tracking. For a product that changes dimensions, that keeps the shot correct instead of framing where the product used to be.
Both are edit-time invisible
In edit mode, markers and focals do not behave as they will for a customer, because conditions are not applied while you are working. Markers appear regardless of their conditions so you can position them, and focals never fire.
Press Play to see them work properly. If a marker seems to be missing in the editor, check whether its debug toggle is switched off in the 3D view's panel.
Use fewer than you want to
Three well-chosen points of interest beat twelve. The purpose is to direct attention, and a model covered in markers directs nothing.
The same restraint applies to focals. A camera that moves on every single option becomes seasickness, while one that moves for the two or three choices that genuinely change the product feels considered.