Blender navigation

The viewport navigation of Blender has been subject to much confusion.
Beginners tend to be especially confused about certain things like e.g. why the viewport stops zooming after zooming a certain distance. But even seasoned Blender user’s tend to not get the way Blender navigation works exactly.

But before I start my topic: Yes I am aware that this absolutely isn’t a question forum, however when it comes to Blender navigation the documentation is so poor that except for the people who have developed this only few people know how it works and yes I tried researching/asking on sites like Blender stackexchange/artists with no avail (the closest I got to an answer was 3d view - Why does the zoom sometimes stop at a point? - Blender Stack Exchange).
There doesn’t seem to be a single place where the way Blender handles navigation is documented at a satisfyingly complete and accurate level, as even the official Blender documentation is only covering this topic at a very rudimentary level.

So to update the horribly vague Blender documentation I want to ask a few questions.

Blender uses a central point as a pivot point to orbit around, which the viewport camera is always facing. This central point has 3 parameters: location, distance, rotation. This pivot point has a location in 3D space (like the 3D cursor) and always stays in the center of the viewport (unlike the 3D cursor), so if you pan(which is convetionally called truck) the viewport the central point moves along so that it stays in the center of the viewport, meaning that it moves parallel to the direction you are panning(trucking) is all that correct?

There is a distance parameter of the central point, which controls how far away the viewport camera is from the central point. The action which in Blender is confusingly called zooming is changing that distance parameter, which then results in the camera moving closer/farther to the central point (which conventionally is called a Dolly). Zooming in Blender despite it’s name does not change the focal length of the viewport camera. The action which is called Dolly in Blender moves the 3D location of the central point and does not change the distance parameter of the central point. Is all that correct?

Is there a way to expose the parameters of the central point?

Apparently the central point has a third parameter called rotation, which somehow controls how the camera is orbited. What exactly does this rotation parameter represent and how exactly does it control the orbiting of the camera? Is it a reference vector which when rotated by the rotation values of the parameter will point towards the camera?

The speed at which the viewport/central point moves while panning(trucking) is greater when zoomed out than zoomend in. In fact when completely zoomed in the speed of the movement slows down to a crawl. What is the mathematical realtionship between the zoom and the speed at which the viewport/central point moves?

Under Sidebar(N-panel)->View there is an option called focal length. When in perspective mode this focal length is the same as the focal length option of cameras in perspective mode. However when I switch to orthographic mode this option still stays the same, while cameras switch their focal length option to the orthographic scale option.

The orthographic scale option is pretty self explainatory in cameras but what does the focal length option in the orthographic mode of the viewport camera mean?

I noticed that Blender’s viewport does a pretty good job at keeping object’s sizes consistent while switching between perspctive and orthographic. Does Blender somehow convert the viewport focal length option in the background to a fitting orthographic scale? And if so what is the mathematical relationship?

The perspective viewport camera has an option to set the focal length, but to determine the field of view a sensor size is also needed. Is there an option to change tihs sensor size or is it set to be constant?
If it is constant what is it’s value?

Under Edit > Preferences > Input > NDOF> Show Navigation Guide there is an option to show a so called navigation guide, which will appear as a blue dot in the center of the screen. Is that a visual representation of the central point?

Thank you for your answers and your contribution to a better Blender documentation!


Alt+mmb sets focus point solving stucking.

Where panning is called trucking?

Panning is incorrectly named in Blender because it’s a camera movement that supposedly pivots the camera from side to side, without moving it. Trucking is more accurate, but also incomplete : it means moving the camera from side to side to follow a subject, but it doesn’t include vertical movement in its typical sense. Truly there’s no word (that I know of) that corresponds exactly with the range of motion of panning in Blender : freely moving the camera on the plane defined by the axis of view.

From my experience most of software (like autocad or archicad) call view-aligned camera movement as pan, so I never faced such a differentiation.

I agree, teaching blender controlls have occassionally been difficult due to this focus point taking a while to understand, yet there is no doubt how effective the controlls are once you get the hang of it.

Some way of visualizing this focus could perhaps make the learning process a lot easier when teaching navigation.

Alternatively, displaying control options like dolly view more clearly could help, as that feels unecessarilly hidden yet overwhelmingly useful for beginners from my experience.