[Insight-users] Exceptions while executing example "DigitallyReconstructedRadiograph1" on a dual CPU machine

[Miller, James V (Research)]

Stefan, 
 
I checked in a fix to the RayCastInterpolateImageFunction to make it thread safe.  You access the change via CVS.  Let us know if you have any problems.
 
Jim

	-----Original Message----- 
	From: insight-users-bounces at itk.org on behalf of Stefan Wesarg 
	Sent: Thu 4/7/2005 8:44 AM 
	To: Insight-users at itk.org 
	Cc: 
	Subject: [Insight-users] Exceptions while executing example "DigitallyReconstructedRadiograph1" on a dual CPU machine
	
	

	Hello,
	
	I compiled and linked the "DigitallyReconstructedRadiograph1" example
	into an executable file that is perfectly running on a single processor
	machine. However, if I run it on a dual processor machine it crashs -
	sometimes (yes, only sometimes) throwing an exception. Switching to
	debugging after that exception reveals problems during the execution of
	the code in the class <itk::RayCastInterpolateImageFunction>. The code
	crashes in an unpredictable way in several methods:
	- InitialiseVoxelPointers() - "The ray traversal direction is unset "
	- GetCurrentIntensity() - "The ray traversal direction is unset "
	- CalcPlanesAndCorners() - "Division by zero (planes) "
	- AdjustRayLength() - "The ray traversal direction is unset "
	
	Again, this problem occurs only if the program is started on a dual
	processor machine. (The executable has been built on that same machine.)
	That's why I guess that it might be related to the threaded execution of
	the <itk::ResampleImageFilter>.
	I executed the code in both ways, without providing input image data and
	by specifying a 3D input data set (MHD format), and also changing values
	for the DRR generation parameters from the default ones did not make any
	change.
	
	Can anybody confirm/replicate that behavior? Any ideas how to overcome
	this problem?
	
	My configuration is:
	- ITK 2.0.1 (built with "BUILD_SHARED_LIBS=OFF")
	- Win2k
	- Visual C++ 6
	- Dual Athlon MP 1800+
	
	Thanks and regards,
	Stefan
	
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	Dipl.-Phys. Stefan Wesarg
	
	Fraunhofer Institute for Computer Graphics
	Cognitive Computing and Medical Imaging (A7)
	Fraunhoferstr. 5, 64283 Darmstadt, Germany
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	email:  stefan.wesarg at igd.fraunhofer.de
	http://a7www.igd.fhg.de/persons/swesarg/swesarg.html
	
	phone:  ჽ 6151 - 155 511
	fax:    ჽ 6151 - 155 480
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