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Surfacing with Scanto3D

Question asked by David Murray on Mar 21, 2008
Latest reply on Jun 10, 2009 by Timothy Wieck

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Hi

A kind sponsor of our race team scanned our engine recently. I have received the data from them as an igs and stl file. If I open the data in solidwwrks, using scanto3d, I can create a mesh of the engine, but whenever I try and create the surfaces I just get an error saying surfaces cannot be generated. Any help would be much appreciated. Please find enclosed a screen shot of the mesh.

Cheers

Dave Murray
Cardiff Racing
www.cardiffracing.com

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sxv mesh with hard points3.jpg49.3 KB

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Matt Lombard Mar 21, 2008 12:26 PM
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Mesh and nurbs surface data are fundamentally different, and converting between them is not (yet) a true button-push operation.

If you have an IGS file, is it just a point cloud or is it nurbs surfaces? Try to open IGS without ScanTo3D, and see if your sponsor already did the work. I'm not sure there is any simple advice one could give a novice to make this kind of work doable, other than to encourage you to learn about the process with any of the tutorials included. Where you go with it also depends on what the end use of the data will be. If all you need is a display in an assembly, the STL data may be good enough, using a graphics body. If you want a parametric model, you will need to go a step further, and rebuild the part with features, which will take some additional patience.

Best of luck.
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David Murray @ Matt Lombard on Mar 21, 2008 1:18 PM
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Hi Matt

Thanks for the prompt reply.

I tried opening the IGS file normally and it just appears as a point cloud. We basically want to use the model to place in an assembly to chekc fit/packaging etc. Any critical mounting points etc I have as a seperate set of probed data that I can overlay onto the engine outline.

Are there any tutorials around for Scanto3D as I can't seem to find any?

Cheers

Dave
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Matt Lombard @ David Murray on Mar 21, 2008 4:00 PM
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Well, it doesn't look like they have a real tutorial, but if you go in the SW help, on the Contents tab, there is a section on ScanTo3D that you can read in 20 minutes or so. I think they are also working on a training book for ScanTo3D.
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1-9C36HC Mar 24, 2008 9:22 PM
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Dave,

I'm pretty confident that you could recreate this engine using ScanTo3D using the guided surface option. This is the best choice for product design and machine casting shapes like this. The Auto-Surfacing option is more organic shapes and is not well-suited for what you have here.

I've done work like this before using ScanTo3D and it does work...with some effort. Make sure you're using the mesh wizard first to get it cleaned up and oriented on your default planes and at the proper scale. I can't over emphasize getting the scale right because after all the work to convert it into a solid, discovering that it is 25.4 times too small is disheartening.

Also, if you do have a combination of prismatic (analytic) shapes as well as complex (algorithmic) shapes, you can do both automatic and guide surfacing thru multiple passes and copies of the mesh. With 2008, you have more guided types to choose.
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Shawn Austin Apr 1, 2008 3:27 PM
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Hi
First, I want to apologize to those who I have emailed through the report this to a moderator. I thought I was sending email to the individual about my problem. I hope I didn't offend anyone. My problem is with importing a surface (stl format) into Solidworks from a reverse engineering program that uses microCT slices to recreate the surface. I rather not go straight into Fluent(CFD software) with an stl format. Wanted to see if solidworks can translate the file. I tried importing as solid/surface body. However, error message appears that it is too many surface and suggest to use stl Graphics. It seems I can't do anything with stl graphics. I tried exporting as parasolid,ACIS, etc. But surfaces is not recreated. I recently learned of scanto3D option. After running surface wizard I am having the same problem. The model can't be recreated. Anyone have any suggestions?
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1-9C36HC @ Shawn Austin on Apr 2, 2008 11:31 AM
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Shawn,

Scaned Sliced data is one type that ScanTo3D does not currently handle well. We are aware of it and we are investigating a solution for a future version.
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Shawn Austin Apr 7, 2008 8:26 PM
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Hi
I would just like to be able to convert the mesh or point cloud (stl) data to a NURBS representation before I use solidworks. Any software that can do that? I have tried importing my point cloud model as a solid or surface body in solidworks with no success!
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1-9C36HC @ Shawn Austin on Apr 8, 2008 6:02 PM
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Can you show us what you're trying to convert to surface, and I can give you a better response to your question.

Thanks
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Brian Hoerner Apr 8, 2008 6:40 PM
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Shawn, typically this has been left to higher order surfacing tools such as Alias, Imageware, PolyWorks, RapidForm and Paraform (now Metris) and others that deal with reverse engineering and surfacing mostly.
My guess is that SW is a good start using the ScanTo3D, but being as young as it is it may not be as fully bloated with automatic options as the others. I have looked at ScanTo3D, and it will meet many needs, but is too lightweight for serious surfacing that comes with dense pointclouds that I tend to deal with, sometimes several million points.
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Edmond Husseini Apr 10, 2008 10:13 AM
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Hi David, I would like to email you a couple of questions about scanning and the engine you are using but I can't seem to email you directly from this forum. Would you be willing to send me a quick email to: ehusseini (at) victoryteam (dot) ae? That way I can reply with the question I have... It would be much appreciated!
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Shawn Austin Apr 10, 2008 8:02 PM
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Hi Mark and Brian

Thanks for your help. The object I want to convert is very porous, almost like a sponge. The smaller the pores the more the surface area. I don't believe a complex geometry like the one I am working with can be recreated, especially with tons of surface area. I will have to look into other software.
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Brian Hoerner Apr 10, 2008 10:25 PM
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Shawn, if you would post a jpeg of a drawing or sketch we may be able to give you a better idea of what tools SW has and what other tools may be a better fit
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mike ekbundit @ Brian Hoerner on Apr 20, 2008 2:04 AM
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I am trying to solve a similar problem with output from a program called Mimics. The IGS file imported into SolidWorks as a stack of ImportedCurves. There was a lot of unwanted info so I've reduced the 7000 something curves to about 25 that I want to keep.

I tried to loft between curves and got a warning about not enough memory. (I have 2 Gig RAM). Now I am trying to smooth each curve to have a better shot at lofting. However, I can't find a way to smooth the individual ImportedCurve entities.

Overall, I too am trying to convert CT scans to a mesh to a NURBS model. Eventually, I need to get my part into CosmosWorks. The attached image is of the remaining curves I'm trying to loft between.
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Matt Lombard @ mike ekbundit on Apr 20, 2008 12:59 PM
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It's not a great way to do it, but if you want to simplify a curve, the only way I can think of, without manually tweaking the iges file is to use a Convert Entities to copy the curve to a spline, and then use Simplify Spline to either remove points or to just show all the points and delete some of them by hand.

The data looks a little noisy, and you may want to smooth it out this way.
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mike ekbundit @ Matt Lombard on Apr 21, 2008 1:40 AM
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Thank you for the tip, Matt. I'll give it a shot and report back. There seem to be a lot of programs that claim to be able to take medical scans and make a NURBS surface from them. So far, I haven't found one that actually does it.

By the way, I enjoyed your lectures at SolidWorks World this year. Didn't sleep a wink in any of them.
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mike ekbundit @ mike ekbundit on Apr 21, 2008 3:38 AM
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After I project the imported curve and convert entities, I end up with an assortment of lines, arcs, parabolas, and splines. I tried Fit Spline on every combination of elements I could think of with the same error "Failed due to geometric conditions." I tried constrained, unconstrained, and fixed as well as a wide assortment of tolerance values. I also removed all of the sketch relations and tried it that way, then all of the above in a 3D sketch. Finally, I tried it by picking the original imported curve.

The only way I could get a single spline segment was to pick one piece at a time. But then I couldn't create them in a way where they joined each other. For example, I could Fit Spline on segments 1 and 3 but not on 2.

Did I miss something stupid? Maybe I'm just sleepy.
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Kevin Quigley Apr 21, 2008 9:24 AM
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I should state here that I am a Classic only user and don't use Scan to 3D - I use VX and Rhino to handle the mesh side to generate curves but I have occasionally imported rough mesh intersection curves from these into SolidWorks as IGES. The workflow (I use) is to make 3D sketches or 2D sketches of each curve then use the loft surface tool. The big problem you will have is that a typical scan curve set will have a zillion points on it and will in fact be made up of loads of line segments. Generally the scan software can deal with the curve creation side but even then on complex forms it will create issues. Apps like VX are pretty good at creating freeform surfaces from point clouds or heavy data sets. SolidWorks, in my experience, is better at creating surfaces from quality splines.

One question I have though. Why don't you just do all this in Mimics itself? That has a MedCAD add on/module that lets you tackle all this. http://www.materialise.com/mat...e/view/en/92486

The basic issue is that applications from Materialise (like Magics and Mimics) are designed to handle polygonal data and meshes or point cloud sets from scans - and they are generally pretty good at that. The workflow the Materialise are promoting, of course, is to build the models as polygonal data from scans, use the various Mimics modules then export to STL and build the implant (or whatever) from Magics and preferably using Materialise as the bureau! Not daft those Belgians

If you really must rebuild in SolidWorks the best option would be (or rather the way I do it - not necessarily the same thing!) is:

1. Import the curve set as IGES
2. Create 3D sketches for each individual curve or collection of lines by referencing those lines to the sketch
3. Loft a surface between them

If you run out of memory try trimming the 3D sketches so you are only lofting say quadrants of the overall shape.

To be honest though I think your best bet would be to use a polygonal modelling system and create the surface in that and export it back to SW as an STL or even IGES. I've not tried this type of application in Rhino but it has a fairly extensive set of tools for surfacing from all kinds of curve.

Out of interest what is the ultimate aim of this?
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mike ekbundit @ Kevin Quigley on Apr 21, 2008 2:08 PM
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One of the driving factors in my project is not to get married to any given software and use open source like OsiriX where possible. SolidWorks and CosmosWorks licenses are already available. The issue then becomes finding programs that will export something that can convert to NURBS. The programs I've tried so far will export STL but those import with thousands of holes or too many surfaces.

Yes, I can use the Mimics module. And if I end up buying Mimics then that would seem the way to go. Crossing back and forth between polygon and NURBS is tough.

In the mean time, I am looking for a generic method. So far, I can get an IGES that imports as curves made up of hundreds of segments. Fit Spline won't fit so I may have to manually trace each curve then loft between. I can Convert Entities to get a sketch but there are too many features to use in a loft (your suggested Step 3) and SW errors off.

The end goal is to create a parametric model to do fracture analysis with SolidWorks and CosmosWorks. The generic bone I'm building could then be connected to a design table.

Thanks for the input. Maybe trying to incorporate SW and CW is too steep a hill to climb and misuse of the application?
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Matt Lombard @ mike ekbundit on Apr 21, 2008 3:13 PM
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mike ekbundit wrote:

Crossing back and forth between polygon and NURBS is tough.

I don't think you fully appreciate the import of your own words. Have you actually completed a conversion yet?

The end goal is to create a parametric model to do fracture analysis with SolidWorks and CosmosWorks. The generic bone I'm building could then be connected to a design table.

It sounds like you don't understand the nature of the conversion or the nature of parametrics. Why would you want to create a parametric model from static data? There is no purpose. Do you really care about the parametrics? Are you going to try to change the model once you create it?

Why don't you provide data, and I'll give you a little demo on what it takes to do what you are after. Can you send or FTP the data?
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mike ekbundit @ Matt Lombard on Apr 21, 2008 4:31 PM
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Yes, I plan to be able to change the model after I build it. I can't get enough bone samples to create multiple models. It would be better for me to build a generic bone with changeable parameters. I'm using the scan data I have as a starting point for geometry. To your point, I suppose it would be just as valid to create a surface or body because I want to set all of the adjustability anyway.

No, I can't say I fully understand this process. That's why I'm writing a paper about it and annoying people with all these questions.

Yes, I know there are bones available for purchase but none of those are accurate for infants. That's why I have to start with scan data of an actual subject.

What data format do you want? I have an IGS that I've cleaned and imported as a SLDPRT. I also have an STL.

Your help is greatly appreciated. Thanks for your patience.
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mike ekbundit @ mike ekbundit on Apr 24, 2008 9:03 PM
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It has become painfully apparent that using a mesh model as a starting point in SW is a bad idea. Better to create something from scratch. Thank you all for your feedback.
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Tony Vitale @ mike ekbundit on May 6, 2008 7:45 PM
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I use the next engine scanner, and then import the .scn file to SW a lot, and have pretty good luck. All i do thought since my parts are somewhat complex is import the mesh, and orient it to the standard planes. then build my SW geometry around it. Since its a mesh file you can snap lines etc. to the mesh to get a real good accurate reprentation. I've never been successful at letting SW generate surfaces using scanto3d tools. Its ok for simple parts, but anything complex its not worth the time.
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Jacky Chu @ Tony Vitale on May 7, 2008 5:49 PM
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I have a quick question relating mesh in Solidworks. I started with a file that has a mesh surface in it and design my part around it. (the mesh is just a reference for my design)

I had right click on the mesh surface and hide it. (so i can see the part i design without the mesh in the way)

After i saved it last night and I opened it today. the mesh is still hidden. right clicking on the mesh item listed on the feature tree does not show an option to unhide it.

Does anyone know how I can unhide the mesh?

Thanks in advance for any pointer.
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Tony Vitale @ Jacky Chu on May 9, 2008 12:01 PM
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Finally!!!! Someone with the same problem i'm having!!!!

I've been trying to get answers to this problem for months. I have my VAR involved, and taling with solidworks. Still with no answers. According to them I am the only person ever to report this issue. now i see someone else.

Feel free to email me and we can gang up to get this fixed.

tonyv@avstardirect.com
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1-9C36HC @ Tony Vitale on May 10, 2008 3:03 PM
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Tony, I have seen this before in 2007 ScanTo3D and reportedly have fixed this issue. 1) What version of SW and SP are you on? 2) when you reopen the file and the mesh does not show, are the ScanTo3D tools available? 3) Try this: File>Open Change file list type to: .dll and open the following file: C:\Program Files\<install directory for SW\ScanTo3D\Addin\swngre.dll If this still does not resolve the problem, please email your email address to me mbiasotti@solidworks.com and I'll provide you with an FTP upload site and I'll submit it and get back to you. 
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Surfacing with Scanto3D

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