Rhino 7.1 bug - DollyZoom distorts perspective view

As you astutely quoted from the Rhino documentation DollyZoom changes the camera location, and changes the lense length (or focal length so you will) at the same time.

The camera widget shows the camera viewpoint at the tip of the pyramid. At the base of that pyramid is the target plane. Between the viewpoint and the target location you have the camera location. Maybe a better name could be view volume. But we call it the camera widget instead. So, camera location (and camera viewpoint) changes very much. Your shared screen recording could not be any clearer. Target plane stays in place. That is how dolly zoom works. Feel free to insist the camera location doesn’t change, but that will only underline the amazing unwillingness to accept explanations from other users, as well as countering what the documentation says.

If you don’t want such distortion in your results you should not cause such a large field of view. This is entirely up to you.

To just dolly the perspective viewport you can use alt+RMB drag. In the docs it is called pan in/out , but it really is dolly.

For what it is worth, Blender and Godot engine both have very similarly behaving camera widgets to Rhino, and I would not be surprised if more 3d packages have something similar, but then again I don’t know beyond these.

We are all clear about what you think the command should be doing, while in fact it is supposed to do something else. You need to be using other commands for walkthrough/flythrough or just moving the camera around. This once is specifically designed to move viewpoint location along with lens compensation for a specific DollyZoom effect. Not just Dolly. For that Nathan’s suggestion could be a good start, but there are many other ways, including Walkthrough commands, 3dconnexion device or some plugins for model exploration.

This thread after all the clarifications looks like you still complain that the _Line command is not drawing a Circle :wink:

I think you have all the info here which should be helpful to understand how it works and why. Up to you how you choose to use it.

Best,

–jarek

In case it wasn’t clear yet:

DollyZoom \neq Dolly

(You are looking for Dolly).

Dolly is not a Rhino command.

Zoom is the Rhino command which moves the camera location but does not change the focal length (view angle) of the camera.
The Zoom command moves the viewport [camera].

ZoomLens is the Rhino command which changes the focal length of the camera but does not move the camera location.
The ZoomLens command adjusts the lens length of the viewport camera in a perspective view.

The choice of words for the commands can be confusing because zoom to many people means changing the focal length but not moving the camera.

Indeed. I did not mean the Dolly as a command, but as concept.

And I fully agree with the confusing terminology

Zolly? We can thank Alfred Hitchcock of the Dolly Zoom.

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Rhino documentation calls it “Pan perspectives view in/out.” This shortcut existed in Rhino 6, but, somehow, I did not discover it, probably due to its confusing name. It sounds like a pan, but it is really a walkthrough or a flythrough. In my opinion, this flythrough is much more useful than the DollyZoom. I wonder how many Rhino users know that the flythrough exists in Rhino. (By the way, the flythrough is also activated by the scroll wheel + alt. The scroll wheel is easier to use than dragging the mouse.)

We have wasted some time because some of us did not define the camera. Finally you (Nathan) explained this misunderstanding. :clap: (I defined the camera as the entire camera widget at the beginning of this debate.) There is still the grid distortion bug.

I’m glad that got settled now.

Not sure if we can call that a bug. It is how the lines get projected on the view due to the extreme field of view with the target so close to the camera location.

For what it is worth, here is the documentation on the camera widget in the online help.