CAD software discussion forum > 3D CAD/CAM > recommendations for working with scan data

recommendations for working with scan data

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Kevin

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Registered: 2004-4-26

Message 1 of 7

 recommendations for working with scan data
13-05-2007 02:35 . pm | View his/her posts only
I've just bought a NextEngine scanner and been havign a play with it on a couple of finished jobs, Got to admit I'm struggling to get a decent workflow going. What I will typically use it for is to scan parts that I need to model new parts to mate with - example being a bathtub foot mating with an existing bath design, or a plastic part that needs to mate to a ceramic part (where tolerances are pretty wide).....

What I would typically aim to do is to scan the existing part and create a trimming surface for the part I'm working on, but I am finding issues that I can't get answers for....

1. Is there any way to create intersection curves from a VX generated surface or solid and a scanned mesh?

2. Similarly, can I project the edges of a surface or solid or curve onto a scanned mesh?

3. Ways to align the scan mesh with existing VX geometry (biggest issue I find is that the scans come in at odd angles or orientations and when I rotate or move the mesh it rotates or moves from a origin that is not the centre of the mesh but the world centre...I am going to double check old posts as I can recall something about this....). But in any case it would be good to have an ALIGN MESH tool where perhaps we select points on the mesh to align with existing VX geometry.

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ChrisWard2k2

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Registered: 2011-11-22

Message 2 of 7

13-05-2007 09:24 . pm | View his/her posts only
Hi Kevin
The Mesh ( = STL) data is not terribly useful for most modelling tasks - you can't do the stuff that you can with nurbs surfaces, such as intersections. The rules are about to be changed by NextEngine however, because their output software will shortly have an update to produce STEP files. These files are not a conversion of the mesh to larger-area faces, they are essentially a "STEP Mesh", so still not great but definitely more usable in the CAD domain (a struggle, but you will be able to get an intersect). NextEngine are also working on a real nurbs output via IGES/STEP. I think that update will be at extra cost......
You can import a point cloud instead/as well as a mesh. That gives you the opportunity to at least define a face that describes the interface between your main nurbs model and the mesh, more if you have the time and patience.
To transform the mesh to it's correct location, define a local datum for the mesh, then move it datum-to-datum. Depending on your requirements, you can get a lot done by defining one or two primitive solid shapes "over" the Mesh, picking up on key points.

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Kevin

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Registered: 2004-4-26

Message 3 of 7

15-05-2007 02:31 . am | View his/her posts only
Thanks Chris, according to NextEngine the ScanStudio Pro software is available later this week but I've signed up for the beta for the time being. The biggest thing I think it will offer is the abilit to output NURBS intersection curves at user defined planes in the point cloud - which is nearly what I am after. I don't expect to be able to use the point cloud data as is for modelling - just wish there were easier ways to create sections or intersections to STL or other mesh format files in all CAD software (not just VX!). I'll try out the ScanStudio Pro software and see if that does the trick for the time being.

Thanks.

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Kevin

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Message 4 of 7

15-05-2007 06:10 . pm | View his/her posts only
Just got the update to ScanStudio Pro today as a beta and it can output curve networks through the mesh, which is very useful, and autosurfaces as well, but from what I can see it gives results similar to the surface from point cloud in VX......still lots of playing to do though ;-)

(Aside.....using scan data with a modelling task would make a very useful tutorial for VX.....)

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Steve

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Registered: 2004-3-1

Message 5 of 7

21-05-2007 11:41 . am | View his/her posts only
Chris and Kevin,

The alignment of scanned data can be tricky. The Datum-to-Datum command will work only in the most rudimentary situations. There are several software packages out there that will perform complex aligments of scanned data against CAD surfaces or other point clouds. These include Geomagic, Polyworks (which I use) and many CMM software packages.

We wrote a program that perfromed these alignments way back in the mid 1990's. It ran in VX "classic", AKA Varimetrix. I have submitted requests for this functionality in VX. If it existed, VX would be the tool of choice for inspection work. Many peope (including me) would be willing to pay a few thousand dollars for this VX module. With all the new lower cost scanners on the market, I hope it becomes a priority for VX development.

Steve

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Kevin

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Registered: 2004-4-26

Message 6 of 7

21-05-2007 03:08 . pm | View his/her posts only
Got to say that alignment is the big issue for me. Whilst the Next Engine scanner is very good there is no way to create an accurate datum when you are scanning most objects on the autopositioner. The scanner seems to be aimed at the visualisation market - which is OK - but it would be so easy for them to just add decent datum tools.

I've seen the NExtEngine SolidWorks plugin and it looks OK but again no real way to set datums. VX are.......that far away from having all the tools we need to use this scanned data effectively.

Bob, Chris, Mike etc. please take a good look at what Next Engine are offering in the base software and the new (as in released next week) added value offerings. Currently I'm using ScanStudio to do the scans and export the data then VX to manipulate the mesh......a few more tools would be good to enhance the ability to actually use the data for design and inspection.

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ChrisWard2k2

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Registered: 2011-11-22

Message 7 of 7

21-05-2007 07:00 . pm | View his/her posts only
Hello chaps

We are working to improve the tools, it is of course going to take some time.

The NextEngine tools for supporting the item for scanning are rudimentary, but you could use a "proper" support base/framework instead, in which case you can include key positions on that frame in the scan for later reference in CAD. Since the scanner is not going to give you a specific point pick, you will need three datum objects that can easily be re-created in VX as primitives - spheres or cylinders could be used for example.
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