How is testzbiasfactor still a thing

I still have to use testzbiasfactor on pretty much all the models I work on. Sometimes it just never does the trick, it only helps slightly. This is something I never come across in my other modeling programs, nurbs or otherwise. I know I’m being a pain bringing this up again, but surely I’m not the only one having this issue.

Rant complete…

thanks for all the help on the WIP so far.


That’s because you are using the Rhino viewport the way it was designed to be used.
You are Zoomed in close to a small portion of a model that covers a huge coordinate range.
This is a common situation in architecture and in civil engineering work, but not in industrial design.

Hi John,

I understand that part, but testzbiasfactor is not able to remedy the problem after I zoom out. As you mentioned, unless I’m zoomed in pretty close I see edges behind surfaces. Is there procedure I’m not aware of that fixes this issue? Also, you are indeed correct I do use the program for Architecture. Rhino WIP is being developed to support Arch. & Industrial design correct?

Thanks again for the help.


The V6 display has not been rewritten to specifically support the special needs of architects.
We are aware of the problem. I don’t know what the Grand Plan is to address it going forward.

Gotcha, I humbly ask that Mcneel try to fix this issue with architects in mind. There are a great many of us using Rhino.

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What if fixing it for architects breaks it for industrial designers?
How do we handle that?

Is the issue really that black and white? I have used several 3D modeling programs that can handle multiple viewport scales without distortion.

That being said, I can only imagine the complexity and hard work that goes into fixing this kind of problem. But is the testzbias issue so large you’re willing to alienate an entire sector of users?

That is not a rhetorical question by the way. You’re the only person so far that has attributed this problem to the industrial design focus of Rhino, which I appreciate very much, as I don’t know what goes on behind the scenes.


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This isn’t accurate. We don’t design the display for specific product types. The problem has to do with small details in models that are very large in relation to those details which is common in architecture (but definitely not limited to architectural models).

Technically, we should be able to improve this by switching to an OpenGL depth buffer that has a higher resolution than what we are currently using. Switching to a higher resolution depth buffer is something we hope to activate in cases where the graphics card supports it.


Hi @stevebaer,

Sorry for the delayed response. Thanks for the explanation.


Sorry folks for digging up a a vintage thread but i’m having a right old mare with this problem.

We’re trying to create numerous set layouts and as you can see when you zoom out the 4mm skin ply become see through. Is this really a limitation of rhino 7 working at this scale?

z bias funciton less helps slightly but not enough to work with

seems to be present in ray trace render as well

any pointers would be gratefully received


Hi Jack - - can you turn on the camera in this view (F6 key) ,. and in Top, zoom Extents and take a screen shot of the camera and the overall scene there?


Hi Pascal,

25mb drawing, using blocks. Its present in even the smallest element 1220mm x 610mm.

Really appreciate you looking at this.