Walk / Fly Functions

[regcal]

I am trying to review  a file and when I use the walk or fly function the model disappers.  Is there a setting that is making this happen, or a setting that needs to be corrected?

Thanks in advance!

[lee.mullin]

This is likely to be related to the culling planes, they are invisible section planes we draw to improve model performance worked out on a model by model basis.

You can modify these manually (not recommended unless you are having problems) by going into File Options on the Home tab, and change the Near Clip Plane to 1/10th the current value, and the far clip plane to 10 times the current value.

Please let me know if this works for you.

[revitforbreakfast]

Hi Lee,

I've been curious about how culling planes work. I've been testing this out in my model which is a structure about 80m x 225m x 25m . The model is about 35MB comprised of 7revit models and one civil 3d.

How do you determine the numbering for near and far based on project size?

[lee.mullin]

It's not something we really can talk about on a public forum but the rough idea is that a plane is drawn just infront of eye level and another one at what may be considered a vanishing point. So everything in between would be visible and we aren't drawing things behind you, for example, at a detriment to performance.

Sometimes like this they can be miscalculated, there's a long list of reasons why this may be, most commonly it's due to some spurious geometry or a huge ground plane which changes the bounding box of the session. Sometimes it can be due to avatars, distances from camera, odd scales. In the most part you should never need to touch them, and unless you have problems, we recommend you don't.

I hope this helps.

[regcal]

Hi Lee,

Changing the culling planes did not help.  Any other suggestions on what it could be?

Thanks again for your time and information. 

[lee.mullin · Accepted solution]

I'm fairly sure that if this only occurs on Fly and Walk mode then this is likely to be a Culling issue due to it changing the camera to perspective mode.

Can you send a screenshot of the Culling Options? Maybe try reducing the near clip plane to a much lower value?

Alternatively in another navigation mode, do View All on the model, see if there's any geometry a long way away from the model and hide that. If it zooms out so far that you can barely see the model then it's very likely to be a spurious item that needs to be deleted or audited in the original model.

[regcal]

After viewing the entire model I was able to find a piece of geometry that shouldn't have been there.  I hide that item and it seems to be working fine.  Thanks for your help.