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Author Topic: Enhancement NEAR Z-limit  (Read 4645 times)

maxxarcher

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Enhancement NEAR Z-limit
« on: June 17, 2008, 02:39:38 pm »

Hi Steve,

Could the NEAR Z-limit be changed to accept values as low as 0.001? I work with Poserīs very tiny Wavefront objects which always get clipped when zoomed in. Rescaling would obviously do the thrick, but that creates extra scale problems when importing the objects back into Poser as morph targets.

A bug in this respect: when the clipping occurs, normal sized Anim8or objects persistantly get clipped too, even after closing all scenes and creating a new one. Reset to "defaults"? Only a program restart cures the problem now. Poser for example has a preferred launch state for each scene which can be set in itīs preferences, "factory defaults" or "user default". The later can be set by saving the current settings for a scene.

Cheers, Maxx
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5L1D3R

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Re: Enhancement NEAR Z-limit
« Reply #1 on: June 18, 2008, 10:34:56 pm »

I've noticed a definite problem with the near Z limit with ART, but Scanline appears fine.  I am working on a model of a ship, uing the default measuring units as inches.  When I render with ART, the first 3rd of the hull gets lopped off.
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karate5662

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Re: Enhancement NEAR Z-limit
« Reply #2 on: June 18, 2008, 11:20:28 pm »

that's strange.
When i use ART, i can get as close as i want to my objects and nothing gets clipped off.
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Steve

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Re: Enhancement NEAR Z-limit
« Reply #3 on: June 20, 2008, 06:08:49 am »

Yes there seems to be several problems with the Z-near setting.  I'll look into them.

#097-011 - Multiple Problems with Z-near.
« Last Edit: July 13, 2008, 10:05:04 pm by Steve »
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Gregory

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Re: Enhancement NEAR Z-limit
« Reply #4 on: June 23, 2008, 09:56:58 am »

I'm having the opposite problem; objects very far away are clipped off:  I have set Z_Far to 100000 and more, yet large objects at beyond 12,000 meters are invisible.  Is there a limit on the distance that can be rendered?
« Last Edit: June 23, 2008, 10:06:57 am by Gregory »
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Gregory

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Re: Enhancement NEAR Z-limit
« Reply #5 on: June 26, 2008, 06:22:07 am »

Steve, can you take a look at this one please.  http://www.anim8or.com/smf/index.php?topic=897.0
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Steve

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Re: Enhancement NEAR Z-limit
« Reply #6 on: July 13, 2008, 10:02:36 pm »

I've fixed several problems with z-limits.  The scanline and OpenGL renderers should use a project's environment settings now.  I've also set the lower limit to 0.01.  The upper limit is still 100,000.  Also the ratio of ZFar to ZLow is restricted to 100,000:1.  (The ART raytracer has no limits - it doesn't use a perspective projection of the geometry.)

Relaxing these limits can cause artifacts, I believe, due to the limitations of single precision floating point math but I'm not really sure how bad they are.  I may be able to remove the ratio limit and the upper limit altogether without making them much worse.  There are some articals on that that I'm looking at now.

But be warned: Using very small values for Z-Near causes a serious loss of precision in the depth buffer for things onlt a little bit farther away resulting in improperly rendered distance objects.
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Gregory

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Re: Enhancement NEAR Z-limit
« Reply #7 on: December 09, 2008, 07:46:38 pm »

In scene view there is still clipping in Ortho view and I thin k in Camera view.

Also, why are there two places to set Z limits:  Settings, Environment Parameters as well as View, Z Limits?  Changing one does not change the other, so which is used?
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Francesco

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Re: Enhancement NEAR Z-limit
« Reply #8 on: December 09, 2008, 11:46:10 pm »

Not sure, but maybe there are separate settings, one for renders and one for edit view, really don't know, try to fiddle with the values to see if you can guess the behaviour.
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