setting dimensions in shapes

nilanka · September 3, 2017, 06:57

Hi,

I would like to create a 0.0001 m sphere in pointwise, but minimum allowed radius is 0.002. Is it something related to tolerance ? I changed from the properties, but couldn't make it.

jchawner · September 9, 2017, 19:06

Hello. I replied to this question that you posted to our Facebook page but I'll repeat it here for others who may be interested.

The short answer is that the minimum radius of a sphere is twice the model size divided by 1e6 (1 million). To create sphere of smaller radius than that, the model size needs to be reduced, but with the caveat that model size is not intended to be changed during a modeling session just to work around minimum length requirements.

The longer answer is that a sphere's radius cannot be smaller than about twice the surface fit tolerance (10 times the same point tolerance) because calculations (evaluation, projection) begin to break down beyond that.

September 3, 2017, 06:57	setting dimensions in shapes	#1
nilanka New Member Nilanka Ekanayake Join Date: Jun 2017 Posts: 9 Rep Power: 9	Hi, I would like to create a 0.0001 m sphere in pointwise, but minimum allowed radius is 0.002. Is it something related to tolerance ? I changed from the properties, but couldn't make it. Last edited by nilanka; September 4, 2017 at 22:23.

September 9, 2017, 19:06		#2
jchawner Senior Member John Chawner Join Date: Mar 2009 Location: Fort Worth, Texas, USA Posts: 275 Rep Power: 18	Hello. I replied to this question that you posted to our Facebook page but I'll repeat it here for others who may be interested. The short answer is that the minimum radius of a sphere is twice the model size divided by 1e6 (1 million). To create sphere of smaller radius than that, the model size needs to be reduced, but with the caveat that model size is not intended to be changed during a modeling session just to work around minimum length requirements. The longer answer is that a sphere's radius cannot be smaller than about twice the surface fit tolerance (10 times the same point tolerance) because calculations (evaluation, projection) begin to break down beyond that. __________________ John Chawner / jrc@pointwise.com / www.pointwise.com Blog: http://blog.pointwise.com/ on Twitter: @jchawner

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