Re: Positional Accuracy

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trdecarlo++at++tasc.com
Tue, 19 Sep 95 23:19:16 -0500


One solution I've seen used is to translate your world origin
nearer to your dataset position by some constant value. Then
it is easy to recalculate to "actual" coords from the offset
coords, and you'll avoid the floating point round-off.

(This assumes that you are using the center of the earth
as the world origin.)

Thom

<---- Begin Included Message ---->
Date: Tue, 19 Sep 1995 17:47:46 -0400 (EDT)
From: plevy++at++banshee.camberva.com (Paul Levy)
Subject: Positional Accuracy
To: info-performer++at++sgi.com

We are flying around a relatively large database that was created from
DTED data. The database has been translated to its correct lat lon position.
The problem we have is the X,Y,Z numbers are so large, the image seems
to jitter eventhough the eyepoint is stationary. I would appreciate any
existing solutions or workarounds.

Thanks
==============================================================================
==
Paul A. Levy Interactive Simulation Group
Camber Corporation E-mail: plevy++at++camberva.com
7411 Alban Station Court, Ste B250 Voice: (703)866-5404
Springfield, Virginia 22150 Fax: (703)866-5409

<---- End Included Message ---->

 Thom DeCarlo * Off-site contact info
 TASC * JPSD/IEC, US Army TEC
 12100 Sunset Hills Rd. * 7701 Telegraph Rd., Bldg 2592
 Reston, VA 22090 * Alexandria, VA 22315
 phone: 703/834-5000 * phone: 703/428-7034
 fax: 703/318-7900 * fax: 703/428-7054
 email: trdecarlo++at++tasc.com * email: thom++at++dogwood.tec.army.mil
 ^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~
   . . . Any resemblance between the above views and those of my
 employer, my terminal, or the view out my window are purely
 coincidental. Any resemblance between the above and my own views
 is not-deterministic. The question of the existence of my views in
 the absence of anyone to hold them is left as an exercise for the
 reader. The question of the existence of the reader is left as an
 exercise for the second god coefficient. (A discussion of
 non-orthogonal polytheism is beyond the scope of this article.)

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