View clipping in 2016 pro display problem?


#1

Hi
I am trying to edit and build a model but the view keeps clipping when i zoom in for detail.
I have turned off section cuts and section planes in the view menu
I cannot see any problems in the preferences display menu.
I am a long time user and this is a very simple model.
I am using a dell xps 15, geforce 750, no ext monitor.
any ideas?


#2

Is the camera set to Parallel Projection? If so, set it to Perspective. Is the model or part of it a long way from the origin? Keep the model close to the origin. Turn off layers for groups/components you don’t need to see to reduce the amount of visible stuff that is at a distance from where you are working.


#3

Thanks Dave
Its not the parallel projection but i think you may have hit on something with the origin.
I used and edited a model from 3d warehouse that must have been created in a cad program and incorrectly imported.
it was many thousand times over scale and when i shrank the scale it did end up miles from the origin. I reset the axes but that must just be specific to the model and not the work space. I will go back and centre it.
steve


#4

Dave hit the high points of what to do when clipping is a problem in SketchUp. The following is some additional discussion of why this happens.

There may be some confusion because SketchUp (like most computer software) uses the term “zoom” for what a photographer would call “move the camera”. That is, in a real camera “zoom” refers to changing the focal length (hence magnification) of the lens without moving the camera. But in SketchUp, the ordinary use of the “zoom tool” (as well as orbit and pan) actually moves the virtual camera with respect to the model. When you “zoom in” you are moving the virtual camera closer to the model. And when you move the camera too close to the model, like an old guy not wearing his bifocals the graphics system can’t cope with the near objects. But instead of getting eyestrain, it clips them off. This is standard computer graphics behavior.

In “perspective” mode, the effect of the clipping is as if you have moved inside the model contents. That is, the clipping occurs at essentially the same distance from the “eye” as the image plane. As the camera moves closer to the model, perspective effects get more and more pronounced and the clipping effect is just like in a movie where you magically move through a wall to the inside of a room instead of bashing into it. The clipped objects are, in effect, “behind you” so of course you can’t see them. Because perspective corresponds more or less to natural vision, the effect is usually what you expect.

In contrast, “parallel projection” is an artificial, ultimately unrealistic view that derives from traditional 2D technical drawings in which the emphasis is on flat surfaces seen square on. Perspective effects such as convergence toward vanishing points would detract from the desired emphasis. And in “parallel” mode, as the camera moves closer, the model just occupies a larger part of the screen. Because of how the projection works, the model is scaled without any realistic impression of getting closer, just bigger. So, when near clipping occurs in parallel projection it seems weird and arbitrary, especially when it happens as you orbit around the model. You don’t have a realistic sense of how far away the model contents are, and the idea that something is actually “too close” is not intuitive.

Unfortunately, SketchUp aggravates this problem because it sometimes doesn’t do a good job of adjusting the location of the near clipping plane, particularly, as Dave observed, when the model covers too large an area compared to the part you are viewing. I don’t work for Trimble and don’t have access to the source code for SketchUp, so I won’t pretend to know the technical details of why, but I trust it results from sound design tradeoffs of attempting to have the camera ready to cover the model as you zoom and orbit.

As a footnote, SketchUp also lets you alter the focal length or equivalently field of view of the virtual camera. “Zooming in” on contents that way will usually not produce clipping.


#5

thanks for that, its never bothered me before, I understand how the parallel perspective works, i thought i was having display driver problems. Moving the Model to the origin helps


#6

Thanks
I eventually copied the whole model and pasted into a new document, end of problem.
steve