[Sidefx-houdini-list] Shading artifact when really close to surface

craigleehoffman at aol.com craigleehoffman at aol.com
Wed Oct 21 14:29:59 EDT 2009



Do any of the precision problems improve if you move from 32 bit to 64 bit Houdini?



-----Original Message-----
From: Ivan DeWolf <ivan at martian-labs.com>
To: sidefx-houdini-list at sidefx.com; Francois Duchesneau <sidefx at trinix.ca>
Sent: Wed, Oct 21, 2009 11:19 am
Subject: Re: [Sidefx-houdini-list] Shading artifact when really close to surface

another problem you seem to have is floating point error.
Your are a couple of meters above sea level, but the center of your  
geometry is at the center of the earth, thousands of kilometers away.  
If you move your scene closer to the centroid, you will have fewer  

To understand a bit about floating point error, put down a"box" sop  
(in an empty scene) and hit space-g and tumble it. Nice and happy.
Now set it's X center to 1000000 and hit space-g
tumble and its all jumpy... and one more zero and tumble and it  
doesn't even look like a cube.....

in a computer, if you a really far from the origin and moving small  
distances, you get floating point errors.

The difference betweeen 1000000.036 and 1000000.037 is very different
from .036 and .037 in the computer....

Perfection is achieved when nothing else can be removed
-Yvon Chouinard

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