miauu's Select by visibility is a script for 3ds Max that makes selections based on how objects appear in the viewport. It can select every object in the current viewport, including both the visible ones and those hidden behind other geometry. You can also narrow a selection to only the objects that can be seen in the current viewport, or only the ones that cannot be seen because they sit behind something else.
The same logic extends across the full layout: the script can select objects that can be seen simultaneously in all viewports, or those that cannot. On top of that, you can pick one or more obstacle objects and then select the objects that are fully covered by them, partially covered, or both at once. It can also show levels of visible objects.
Selection is limited to geometric objects and shapes or splines. Lights, cameras, and helpers are skipped and won't appear in the results. Version 1.4 works with 3ds Max releases from 2017 through 2027, and a demo video is available.