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Surfacing IGES point clouds
2

Surfacing IGES point clouds

Surfacing IGES point clouds

(OP)
I've been stuck with this forever. I have an IGES file of a 3D Surface scan with about 8000 point clouds. I need to somehow put a surface on the point clouds, and need to keep the cross section concentric. Any help would be truly appreciated.

After the surface scan, I have a lot of point cloud data (about 8,000 points). Here is what it looks like in SolidWorks:


The object is a heart valve stent, so imagine a cosine wave around a cylinder...

So the real object that we scanned has a circular cross section, and we are trying to recreate a 3-dimensional figure of the stent. If I look at the cross section, it looks like a bunch of zig zags if I connect the lines, but I need to somehow keep it concentric.

RE: Surfacing IGES point clouds

Hello Bio:  I think this would be a good approach. 1)Import as Solid Body or Surface body under the options button when you import so you can snap to points 2) Use the 3D spline to draw a contiuous spline along the centroid of your "cross-section" 3) Sweep the circular cross section along the spline 4) Fight through the self intersection problem of the sweep in the small radius arcs by doing it in sections. If the "cross section" is of varying cross section you will have to loft it.  Can you provide the point cloud data?

Tom

RE: Surfacing IGES point clouds

(OP)
Hi Tom, thank you for your reply! I find it very difficult to do the 3D spline since the stent involves x,y, and z coordinates at every point, and SW does not allow for drawing with XYZ, only XY, ZY, and so forth.

As for the point cloud data, I have the IGES file. I can upload it sometime, but is that what you were looking for? Thanks so much.

RE: Surfacing IGES point clouds

Yes, post the point cloud data in IGES so I can try this thing.  Thanks, Tom

RE: Surfacing IGES point clouds

The data looks incomplete and pretty noisy.  I don't believe you can make anything useful directly from the data, even if you were to use something meant for that type of work such as Geomagic.  Since you seem to have information about the shape anyway, I think you'd be best just to model it directly in SW, using the data as kind of a "ballpark" approximation check for size and position.  Working with this kind of data is extremely tedious in SW.

To make the shape in SW, either projected curves or a spline on a cylindrical surface would be my approach.  Projected curves would be easier to work with.

Good luck.

RE: Surfacing IGES point clouds

(OP)
My thoughts exactly. The problem with this is that if I just spline and sweep with a measured diameter, would I be able to use this CAD for FEA? The main criteria is that we capture the 3D shape of it, and then we are able to use this CAD to apply finite element analysis.

RE: Surfacing IGES point clouds

Hey Peter, I have started working on the design and would like to know the diameter of the cross section.  Is the wire used basically a continuous loop that is bent into the 3 sided sine wave?  Do you have a photo you can post?
Thanks, Tom

RE: Surfacing IGES point clouds

(OP)
Wow, I didn't know you were going to work on it! Well for the diameter, I didn't have a caliper with me, so I could measure it. However, I think 1 mm is a safe estimate...more like 0.95 mm. How are you creating the CAD drawing?

As for the photo, I cannot seem to get a copy of the picture, but if you go to this animation (http://www.edwards.com/Products/HeartValves/MagnaAnimation.htm), and advance to about 39 seconds into the clip, then you should be able to see it. I tried print screen, but it wouldn't work for some reason. Thank you so much.

-Peter

RE: Surfacing IGES point clouds

Your only hope in SW is to use the point import macro, and then to find a way to use the points to generate a surface. Go here to get it.

http://solidworks.cad.de/mm_24.htm

Convert your .igs file to a tab delimited text file with the xyz data. This is your only hope to create something in solidworks, but unordered scan data is very hard to work with.

What you really need to do is use a reverse engineering app that will clean up your noisey data, then triangulate a surface from the data. You can then use this polygon model for FEA, and if you have the right package you can surface the triangles to create a NURBS or parametric CAD model. Look up Rapid Form or Raindrop or CopyCad or 3d Reshaper to name a few. This stuff gets expensive.

If you post your data I'll take a look at it and give you an example of going from points to polys to nurbs with my tools.

RFUS

RE: Surfacing IGES point clouds

(OP)
Hi RFUS, thank you for your reply! I actually posted the file in the link (yousendit.com link) a few posts before. I tried looking for a iges converter to the xyz data, but I can't seem to find a program that does that or have access to one. Thanks again!

-Peter

RE: Surfacing IGES point clouds

Here is a tab delim of your file, i called it Scan4btabdelim.zip. Units are mm.

Mooload wasn't working so its on this paininthebut site. keep going in till you get it to download... hit the one below where it wants you to pay a buck, and then save target as, then wait a while and it will come.
http://www.filefactory.com/get/f.php?f=bb435c645763e514de61ce18

Run the macro I pointed you towards on this file. Now, if you wanted to surface this in SW, you would have to do this:

Close the 3d sketch. You have to go and 'insert curve through reference points' by selecting the points in each scan line. Use the point selection filter with view orientations. This will take a while. Then create a lofted surface using the curves.

But...You want to sweep a circle around this so now at least you have these points to use as ref geomerty to go in and create a curve around this thing.

If you wanted to have a model for FEA you would need to export your final model as STl which will give you a triangle network or faceted model.

During lunch, I tried triangulating and using and auto surface on this data and its pretty rough.

RFUS

RE: Surfacing IGES point clouds

(OP)
Hi rfus, when I run the macros program, it keeps giving me an error saying that there is an invalid character in the code. I'm not sure of how how to fix this.

However, since you tested that data, and it came out pretty rough, that is exactly what we can't use. I'm going to try to rescan the object again, and take some good pictures of it.

Sweeping the circle around those reference points is exactly what I need to do, but it seems like it'll be more difficult than I ever anticipated. Is there any other way to sweep the circle around? This project is hopeless. Thanks.

-Peter

RE: Surfacing IGES point clouds

Peter, what is the trick to posting an image on this forum like you did? I have a model of the stent wire and want to post an image of it.  

I don't understand the instructions on this website.

Thanks,

Tom

RE: Surfacing IGES point clouds

(OP)
Yeah I tried looking around this forum and have been conducting several searches regarding this, but nothing addressed this specific problem. Thanks for the suggestion though!

-Peter

RE: Surfacing IGES point clouds

If you do this often, you might want to consider buying software. There are a variety of reverse engineering software packages that are tailor made to handle large size point clouds data from laser scans and construct various surfaces from them.

 Pricewise on the low end, you have Rainbows's Geomagic, on the mid to high end, you have Innovmetric's Polyworks, on the high end you have Imageware made by UG (I think).  And that is just scratching the surface.  They will not be parametric in solidworks, although importing from such software should not be a problem for Solidworks.  Geomagic is usually the easiest to use, and Imageware is usally the most powerful.

 

RE: Surfacing IGES point clouds

Can I make the imageshack linked image show up in the forum or do I have to use a web server as you say in your FAQ?  Thanks.

RE: Surfacing IGES point clouds

You could make it show up in the forum, but what you have done is better. It takes up less bandwidth, doesn't mess up the page size (like the first one did because it was too big), helps the page load faster & gives people the choice of whether they view the image or not.

cheers
Helpful SW websites  FAQ559-520
How to get answers to your SW questions  FAQ559-1091

RE: Surfacing IGES point clouds

(OP)
Hello Tom, wow, that looks amazing. If I can remember the stent correctly, that is exactly how it looks like. How did you do that? That looks great! Did you use that IGES file or did you start from scratch? Thanks!!

-Peter

RE: Surfacing IGES point clouds

Peter- I snapped a spline to points in the messy point cloud following roughly the center of the cross section to make a "U" shaped spline.  I then lofted it along its full length.  Looking at the part and the point cloud you could see that the shape is somewhat distorted so I cut the "U" in half and mirrored it so it would be symmetrical. I then patterned that every 120 degrees.  Then I had to add the little hairpin turn to the tops of the three "U" shaped pieces by using lofts.  I think the only critical thing about the FEA is getting the proper radius for the 3 small hairpin turns at the top.  Because the ratio of the diameter to the overall length of the wire I think the larger radii will not see much stress.   

RE: Surfacing IGES point clouds

(OP)
Wow, I can't even comprehend what you did in SW. Given that I have only had a few sessions of SW experience, I don't know if I can repeat exactly what you did. Would it be possible if you upload that file somehow? Thank you so much for your help!

-Peter

RE: Surfacing IGES point clouds

I have been trying to clean up some rough edges on it.  I will try and send it tomorrow.  -Tom

RE: Surfacing IGES point clouds

tommy104 ... any particular reason why you used loft instead of sweep?

cheers
Helpful SW websites  FAQ559-520
How to get answers to your SW questions  FAQ559-1091

RE: Surfacing IGES point clouds

(OP)
Yeah. I've never used loft before. I always thought you would draw the 3d spline through the center, set the diameter, and sweep through the path?

RE: Surfacing IGES point clouds

I actually used sweep to do most of the wire so I told you wrong for the first bit of it - sorry.  I used loft to make the smaller radius areas for no particular reason.  I realize loft is more for varying cross sections.  I have just gotten into habit of using loft more because I want to learn the new 2006 features.  - Tom

RE: Surfacing IGES point clouds

Peter do you have Solidworks 2006? Otherwise you will not be able to look at the part model.  If you need it to do analysis I can export it to step or iges.  -Tom

RE: Surfacing IGES point clouds

(OP)
Hi Tom, the most updated version of SW I have is 2004.5. Is it possible to send it as an IGES file, and I'll open it in SW 2004.5, and then save it as a STL file for FEA with Nastran/Patran? Thanks!

-Peter

RE: Surfacing IGES point clouds

(OP)
Hi Tom, I tried to spline through the center, but I'm having trouble following the circular dimension. How did you go about doing that portion?

RE: Surfacing IGES point clouds

Peter- I snapped a spline to points in the messy point cloud following roughly the center of the cross section as you follow along it lengthwise.  There is no circular "cross section" because the laser apparently did not rotate all around the part and do a good job.   - Tom

RE: Surfacing IGES point clouds

How Do I Make Files Available For Download? ... No Emails Required  FAQ559-1177

cheers
Helpful SW websites  FAQ559-520
How to get answers to your SW questions  FAQ559-1091

RE: Surfacing IGES point clouds

(OP)
Hi Tom, I tried downloading the file, but it has nothing inside. I checked the file size, and it says 0 bytes on the mooload webpage. Is there someway to upload it again? Sorry for the hassle!

-Peter

RE: Surfacing IGES point clouds

Peter - I downloaded from that site this morning to check it and it worked.  I just tried it from home and now it does not work.  I will put it up again tomorrow.  - Tom

RE: Surfacing IGES point clouds

(OP)
Hi Tom, thanks again. I really appreciate it.

RE: Surfacing IGES point clouds

(OP)
Hi Tom, thank you so much for the files! I have a quick question regarding the files. How would I go about changing the diameter of the stent? Thanks!

-Peter

RE: Surfacing IGES point clouds

How much does that cost?

Jason

UG NX2.02.2 on Win2000 SP3
SolidWorks 2005 SP5.0 on WinXP SP2
SolidWorks 2006 SP3.0 on WinXP SP2

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