Reverse Modeling/Analysis 1

[hart2ja88]

Hello,
I am trying to take 3D bone scans (STL files) from cadavers and analyze the movement of joints. How can I make it so there are actual points on the surfaces so that I can attach springs and such to them? I am having trouble doing anything with them other than moving them around. Thank you

 

[JohnRBaker]

There are tools in NX that will help you convert faceted models into surface models. What version of NX are you running?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
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To an Engineer, the glass is twice as big as it needs to be.

 

[hart2ja88]

I am running NX 9.0

 

[JohnRBaker]

Then you should start by looking at the functions found on the ribbon tab labeled 'Reverse Enginering'. The 'Rapid Surfacing' function is where I would try first. Also 'Fist Surface' can be used as well and even 'Rough Offset', which is not found on this tab but can be found using the 'Command Finder'.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[hart2ja88]

I tried all of those functions and none of them seemed to work. In the "Reverse Engineering" function, it will not even let me select anything. Also, I could not find 'Fist Surface' and could not get 'Rough Offset' to work. I am meeting with a professor tomorrow to see if he can help me. If I glean any information off of him, I will update this post.

 

[JohnRBaker]

So you're a student, correct? Student are really not supposed to be using Eng-Tips for help with their assignements.

But let me ask, are the NX models that you're working with, are they faceted or not? If they're faceted then you should be able to select the models in the above mentioned functions. And I'm sorry, the name of the function 'Fit Surface'.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[hart2ja88]

I am a grad student doing research for the Physical Therapy program at CMU/MTU.

I tried the "fit surface" and it gives me a very weird, 2D shape that I do not think is what I am looking for. I am unsure if the objects are faceted. I would assume not, because none of the functions worked. I have been working with this program for about 5 months and have never used a CAD program before, so I am very inexperienced when it comes to operating anything more than basic functions. I would upload the part that I am working with so you could take a look at it, but it is a specimen from a human and I don't know if I have the authority to release it. Also, the professor did not show up for my meeting. I did not get any information from him. I appreciate your help though.

 

[cowski]

If you hover your cursor over the body a "tooltip" should show up; if it says something like "lightweight body", you are dealing with a faceted body.

Another way to check is to use menu -> information -> object..., set your selection filter to "facet body" and see if it lets you select the body. If it does, you have a faceted body; if not, you have something else.

www.nxjournaling.com

 

[hart2ja88]

After reading many forums, I have come across someone who is having a similar problem as me.

http://www.eng-tips.com/viewthread.cfm?qid=157325

 

[hart2ja88]

It is Faceted. Thank you cowski

 

[cowski]

Imported STL files are just the worst.

How can I make it so there are actual points on the surfaces so that I can attach springs and such to them?

To answer your original question, you can create points on the surface if the "point on face" snap is turned on. You'll have to "eyeball" the location, but at least the resulting point will be on the surface.

www.nxjournaling.com

 

[JohnRBaker]

I am a grad student doing research for the Physical Therapy program at CMU/MTU.

When you say "CMU/MTU", are we talking about "Central Michigan University/Michigan Technological University"? If so, which campus are you located at?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[hart2ja88]

I am a CMU DPT student. There is a satellite campus at MTU. I am at the MTU campus (in Houghton, MI).

 

[JohnRBaker]

Note that I'm going to be on campus (in Houghton) for some activities with the ME-EM department as well as the School of Engineering Technology during the week of April 20th. Perhaps we can meet for some technical and/or social interaction.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[hart2ja88]

I would be able to meet up when your in town. The sooner the better...gotta get this research going.

 

[JohnRBaker]

Not sure how much I can help you, but I could give it a look. BTW, have you checked with any of the people who are using NX in their classes at MTU? If you wish, I could give you some contact names, but not here on a public forum. If you look at my 'username' and add TWO periods where it makes sense and then add '@siemens.com' you should get my email address. Send me a note and we can take this offline (or at least off Eng-Tips).

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.