From: owner-3dui@hitl.washington.edu on behalf of Jeff Pierce
[jpierce@cs.cmu.edu]
Sent: Sunday, August 20, 2000 3:29 AM
To: 3d-ui@hitl.washington.edu
Subject: Re: Far clipping planes

At 12:36 PM 8/18/00, lpastrana@altern.org wrote:
>Hi jeff i guess there could be a bilion answers to your question this way... 
>but i believe what determines your Z-clipping planes is the bitdepht of the 
>z buffer on the implementation side; is it 16, 24 or 32 bits, i mean bit 
>depth of your z buffer is THE constant...

[stuff munched for brevity]

>was the most "exact" technically... to be more precise, what you need to 
>determine to set the far clipping plane is : 
>1: what is the longest distance you want to be able to manage ?
>2: what is the precision/scale/unit you need for the z values in your scene ?
>3: does that fit into your 16, 24 or 32 bits z buffer ?

That would probably be the optimal solution.  However, my informal
experience is that people don't actually sit down and calculate the optimal
far clipping plane distance every time they create a new virtual world.  I
asked the question because I was curious what other groups did in practice
and what they got as a default in their authoring tool (and many thanks to
all those who answered).

In case y'all were wondering, the whole line of thought started because I'd
been playing with a few interaction techniques for reaching beyond the
clipping plane in very large virtual worlds (where there's also a lot of
small stuff close together, so that you can't put the far clipping plane
arbitrarily far away).

Cheers,
Jeff