[FR] Tweaking zoom speed in parallel projection


#1

Currently the mouse wheel in parallel projection zoom by a factor of 0.9 or 1.1 per step. This means that zooming in one step and then out one step doesn’t take you back to the previous zoom level (0.9/1.1 ≠ 1.0). The mismatch gets more noticeable the more steps in and out you take and can make it difficult to re-create previous views or create a series of matching scenes.

I suggest tweaking these zoom values to make one the inverse of the other, e.g. to 0.9 and 1.1111111. The difference to what is is now would be so small it isn’t noticeable, other than how it allows you to go back to the exact same zoom level you were at before. No slowdown or acceleration would be perceived by the user.

While at it, if the values where set to (1/2)^(1/8) and 2^(1/8) (0.9170040432046712 and 1.0905077326652577 respectively) 8 steps on the mouse wheel would exactly double or half the zoom. This is how the zoom works in various other programs.

While this would be a very subtle change it would make SketchUp more predictable and therefore easier to use. This would make zooming “just work” in cases where it currently doesn’t. In my view these more or less subtle details that makes the program “just work” without the user having to think about it is what makes SketchUp special.


#2

Does this apply only in parallel projection, as the “zooming” function in perspective has its own unique behavior depending on where the cursor is?

A little off topic but related is that the “zooming” tool/function has always felt like a bit of a misnomer in that a “zoom” in photographic parlance is a change of focal length from a fixed position, whereas the “zoom” feature in Sketchup is more akin to a track/dolly where the camera is moving in 3D space. ( certainly less of an issue in parallel projection).
There are other similar misnomers with the camera tools. Maybe there could be an overhaul of these terms along with the similarly confusing issues with “layers” which might, as has been noted previously, be better described as Tags.


#3

Yup, this applies to parallel projection only.

Regarding the terminology I’m used the the word zoom in a 2D context where it simply means scale/resize the view. This is how the word is used in parallel projection too. In perspective it can be a bit confusing that “zoom” suddenly refers to moving the camera backwards and forwards (in parallel projection the camera isn’t moved when zooming). As you say this is not what the word means in photography. However I think the term zoom for referring to camera dolly has gotten quite widely used in 3D modeling now. Also it makes sense to use the same term for the perspective camera movement and the parallel projection view scaling, as they serve the same purpose to the user, even though they geometrically/mathematically are very different.


#4

It is a curious issue or perhaps just an etymological fallacy. Clearly when dealing with parallel projection or looking square on to a 2D surface with perspective, whether “zooming” or “tracking” it will make no difference to the viewer as there is no “Z” axis info/geometry to indicate shifts in parallax. Other 3D programs like 3DS or even after effects all use a camera, have a camera icon. So that when animating it’s important be aware of camera position vs focal length (tracking/moving vs zooming) as they each produce very different results. Much data in camera tools notes height focal length, roll, tilt etc.etc. You’d think that all camera conventions would be respected?
The camera’s “moves” and resulting shifts in parallax, creates such different looks, so that what we should now refer to as “zooming” is to redifine these long standing terms is a bit backwards?

“When enough people are wrong, they’re right,” (W.Safire)

“zoom extents” from the inner confines of a model clearly demonstrates that the camera/viewpoint is moving out, something that could not possibly be done with a zoom.
Also interesting to note that when in parallel mode and using the “look around” tool (panning) that there is a shift in parallax, something that doesn’t happen in perspective mode (which is correct).

Other SU camera tool misnomers:
“look around” tool is the equivalent of a “pan”
“pan” tool is the equivalent of a “track/move”
I would of also labelled “scenes” as “shots”

Hey, but that’s just me.


#5

In parallel projection/2D I’d say zooming and tracking are different. Zooming changes the scale of the view while tracking doesn’t. Tracking can however cause clipping (hide what is behind the camera) which zooming doesn’t as it doesn’t move the camera.

For perspective cameras I agree the terms used in SketchUp, and various other software, are technically wrong but I’m afraid correcting them would cause more confusion given how used people have gotten t them.


#6

Unfortunately, zooming in SketchUp Parallel projection views does move the “camera” just like in perspective. The reason for clipping in parallel projection is that the camera picture plane gets moved inside your model geometry.


#7

It does not. Zooming in parallel projection only changes the sizing, not the camera position. This is why you can zoom much “closer” in parallel projection without clipping, because the camera isn’t really moving any closer. However, orbit in parallel projection moves the camera and can cause tremendous clipping. As zooming out doesn’t move back the camera it cannot be used to get rid of the clipping. To do this you have to switch to perspective camera, and often find yourself much closer to the geometry than you expected.

Here’s image evidence of the camera eye position staying the same while zooming.
2018-05-04_19h46_50


#8

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