It seems to me that big advances in MCAD arrive every ten years or so. 1986 saw PTC introducing history-based parametric MCAD, and just about everyone made that the standard way to model in 3D. A decade later, Solidworks 95 brought MCAD to Windows, and competitors rushed to Windows to mimic the success of the self-funded startup. A little more than a decade further along, SpaceClaim in 2007 rocked the world by revitalizing direct modeling, forcing competitors to acknowledge this old technology, and so we got Creo from PTC, Fusion from Autodesk, and Synchronous Technology from Siemens PLM Software.
(I am not disregarding other tsunamis in tech, but things like the Internet, 64-bit CPUs, and cloud computing apply equally to all software, not specifically to MCAD.)
The most recent innovation in MCAD arrived in 2015 and in a rather quiet manner. It tries to solve a hard problem: how to merge the editing operations on single 3D body made of meshes and solid models.
Mesh models tend to come from data external to the MCAD software, such as 3D laser scans, reverse engineering, and generative designs. Solid models tend to come from inside MCAD software, either built from scratch natively or imported from other MCAD packages. A common example we see is making a 3D scan of a patient's knee, and then modeling the custom knee joint as a 3D solid.
If, in the past, you wanted to work with both, you needed to convert one into the other: either meshes into solids, or shell solids into meshes. This isn't ideal, as surface data can get lost in the conversion, and you might end up with a creepy looking result. In any case, meshes generated from 3D scans tend to be huge and complex-looking, and so are unsuitable to be represented by solids.
Hybrid Modeling
Until recently, it was best to keep organic mesh data separate from 3D solid models. But now we have hybrid modeling. A typical editing operation involves carving out some of that knee's mesh model to make room for the solid joint; similarly, the solid joint can be edited to adjust to the surface of the knee's mesh model. Or a mesh-based turbine part edited with a solid part. See figure 1.
Figure 1: Spatial's Polyhedral editing solids (left) and mesh parts (right)
It turns out it's a tough job to figure out the editing on both kinds of 3D bodies at the same time. The Spatial division of Dassault Systemes has been revealing a few advances each year. This year, for instance, they added just two functions to its Polyhedra hybrid editing API [application programming interface]: stitch (to directly combine meshes and solids into one body) and move (to manipulate solid faces in a hybrid body).
Note that Polyhedra is not end-user software, but an API that MCAD vendors implement in their software through Spatial's ACIS or CGM kernels. Spatial calls the imported 3D scans the "polygonal" model, and the 3D solid the "precise" model. See www.spatial.com/products/cgm_polyhedra.
Siemens Convergent Modeling
In the kernel world, the arch competitor to Spatial is Siemens PLM Software. So it is not surprising that Siemens revealed recently that it too is working on hybrid modeling for its Parasolid kernel. Siemens calls its technology "convergent" modeling, because it converges meshes (which it calls "facet models ") and solids (or "classic b-reps') into a single model. See www.plm.automation.siemens.com/en/products.
The two competitors take pot shots at each other. Siemens boasts that its technology is integrated into Parasolid, and so has "no delegation to an add-on modeling component," in the way that Polyhedral is an add-on to the ACIS and CGM kernels. In an interview with me, however, Spatial accused Siemens of holding both representations separately internally, rather than truly converging them. Both, ironically, use the same example of a knee joint.
For this year's releases of Solid Edge and NX, Siemens added convergent modeling to its MCAD systems, because it owns all three. The company will continue to develop the technology in the coming years -- just as Spatial is doing.
What's New in Solid Edge ST10
When it came up with Synchronous Technology for mixed direct and history editing, Siemens emphasized the technology's big deal by restarting Solid Edge's numbering system: what would have been Solid Edge 21 became Solid Edge ST -- the dawn of a new era in design. Except it wasn't. Much was missing from that first release, and even in subsequent releases of ST. A decade's worth of updates later, users still can find it difficult to work in with ST.
This summer's release of Solid Edge is ST10, the tenth anniversary of synch tech, but Siemens has a new master plan: its MCAD programs will encompass the entire design process -- from reverse engineering, through design, and finally output to 3D printing. (See figure 1, above.) Siemens calls it "next-generation design" but didn't change Solid Edge's numbering system, sadly; Solid Edge NG would've been cool.
Next-generation design encompasses reverse engineering, convergent modeling, generative design, and 3D printing. See figure 2.
Figure 2: Siemens'Next Generation Design master plan for Solid Edge
Reverse Engineering. When drawings don't exist for parts, we could draw them from scratch. Or we could use scanners to do it more quickly. A scanner uses a laser to find the position and distance (x,y and z) of thousands of points on the part. Software connects every three points with edges, creating a 3D mesh model from the triangles.
Designers then clean up the mesh model by removing facets, filling holes, and smoothing the mesh in Solid Edge. Once clean, parts of the mesh can be turned into surfaces native to Solid Edge with its Identify Regions tool.
Convergent Modeling. To work with meshes and solid models, Siemens provides convergent modeling, as I described above. (See figure 3.) Commands that were formerly only for b-rep modeling now also work on faceted geometry, with no need to convert one 3D representation to the other. (B-rep is short for boundary representation, and is the part of the solid model that we see, such as the exterior faces, edges, and vertices.)
Figure 3: Convergent modeling removing green solid from mesh
Operations that convergent modeling can do include Booleans, sectioning, hole-filling, imprinting, extrusions, mass properties, clash detection, and others. To learn more, check out www.plm.automation.siemens.com/en/products.
Generative Design. Engineers like to over-design parts to make sure they don't fail, but for fields like aerospace and for considerations like cost or weight or space, it's preferable that parts have the least amount of material necessary. Generative design, also known as "topology optimization," auto-magically reworks a part, removing material that is not needed for strength (see figure 4). The result often is strange looking, something that might be designed by aliens.
Figure 4: Generative modeling reduced weight of red sewing machine frame
To use generative design, we tell Solid Edge the material, the constraints (like bolt holes), the loads, and a weight we'd like the part to weigh. The software automatically computes the geometric solution. This technology is not new, but has tended to reside in specialty software external to mainstream MCAD.
3D Printing. Siemens is making a big, big push towards 3D printing, also called additive manufacturing. This is no surprise, given that the company manufactures everything from tiny medical devices to entire railroad trains. It now wants its design software to also be making the parts.
But an interface is needed between the 3D model and the printed part. The part we model might have walls that are too thin for the 3D printer's resolution; it might have empty areas large enough to collapse; it might not even be able to stand upright on the 3D printer's table. The software checks for these and other flaws, and then lets us adjust how the model will be printed. See figure 5.
Figure 5: Solid Edge warning that your model probably won't print successfully
Once the part is ready for printing, Solid Edge converts it to the original STL or new Microsoft 3MF formats, or outputs it directly to Microsoft's 3D Builder app, or uploads it to an online 3D printing service.
So there you have it: a design sequence that runs from reverse engineering through to 3D printing.
What Ralph Grabowski Thinks
Next Generation Design is a big vision from Siemens that encompasses the design process end-to-end. I consider it a spectacular addition to Solid Edge, but core Solid Edge users will probably consider it only peripheral. They continue to be concerned primarily with 3D modeling, 2D drawings, and updating designs -- as are most CAD users, no matter which package they embrace.
On a side note, the big Solid Edge University that occurred each October is no more. It's been regionalized into dozens of events throughout the year in individual cities and countries. I am not surprised, given that only about 500 enthusiasts ever showed up at the annual event, a tiny number compared to the half-million users claimed by Siemens.
Nevertheless, the addition of Next Generation Design and continuing development in other areas of Solid Edge is heartening, because it proves Siemens is serious about supporting Solid Edge into the future. Over time, I feel certain that hybrid modeling will seep into all forms of MCAD, just as direct editing did a decade ago. www.solidedge.com
Translating Between Competitors
Spatial and Siemens use different words that mean the same thing. Here is a guide:
Spatial Siemens
Editor's name: Polyhedra Convergent modeler
Works with: ACIS and CGM Parasolid
Meshes are called: Polygonal models Facets
Solids are called: Precise models Classic b-reps
[This article first appeared in Design Engineering magazine and is reprinted with permission.]
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| Some of the most recent posts on my WorldCAD Access blog:
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The new Rhino 6.0 from McNeel Associates integrates the Grasshopper visual programming language; it is no longer in beta. Also new: the GPU is used for shaders and memory optimization, Make2D is rewritten, and DWG support is better. You can download the eval version from www.rhino3d.com/download
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No surprise at this news: Ray Kurzweil delays the singularity from 2030 to 2045.
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Public service reminder: AI is blackbox. If we don't know how it works, we shan't trust the result. "Missing data hindering replication of AI studies as survey of 400 algorithms presented at major conferences finds just 6% included code, 30% included test data." www.sciencemag.org/news/2018/02/
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The Coordinate Metrology Society last week opened online registration for their 2018 Coordinate Metrology Society Conference being held July 23-27 in Reno NV. (The call for papers is open until March 8.) Register at http://www.CMSC.org
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Corporate biographies are my favorite reading material. Another corporate biography waiting to be written is about the train crash that will become of Magic Leap. www.theregister.co.uk/2018/02/15
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For late-breaking CAD news, follow upFront.eZine on Twitter at @upfrontezine.
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Re: Extending the C3D File Format
@BlackBox_CAD: I don’t know what the ‘Civil3D File Format’ is, but I can’t wait -- especially as the only improvement to speeding up the reading of large models is the new-ish use of external MMS files for large surfaces in 2017-2018, which can bite you: autode.sk/2irfdxk
@SteveJohnsonCAD: C3D /= Civil 3D. fileinfo.com/extension/c3d
@upFronteZine: C3D Labs makes a geometric kernel, so no relation to Civil 3D.
@BlackBox_CAD: Never heard of them before; thanks for clarifying. Any idea why they used the same name/abbreviation? I thought it was a poor choice for Autodesk to use Bentley colors; this seems just as poor of a choice, even if it’s a good product. Perhaps someone @C3Dlabs knows?
@savagemen: C3D came from Core 3D. It is a project name of the 3D engine that lies in the basis of MCAD software, KOMPAS-3D, the very popular product in Russia and CIS. As about Civil 3D, so C3D is only a useful shortcut. The native file format of AutoCAD is DWG.
Nowadays, C3D is the commercially available engine for everyone who wants to develop new 3D software. Perhaps you never heard it before because you are not a software developer. Find out more about C3D at www.c3dlabs.com
@BlackBox_CAD: Thanks for clarifying. I’m aware of the Autodesk side of things, as I use their products (namely Civil3D) daily, which is why your abbreviation of C3D is so confusing, despite sounding like a great development engine.
@savagemen: If interested, there are plenty of geometric kernels worldwide, some of them available to third parties for implementing in CAD/CAM/CAE and other types of 3D software. Recently, C3Dlabs presented a C# wrapper for the C3D Solver and C3D Vision components -- parts of C3D Toolkit.
@BlackBox_CAD: Me a developer? Nope. I just code C# for fun & sell small apps for Autodesk products in +/- 70 Countries. Much to my surprise, I make too much being a designer to warrant more developer time, and I don’t sell my best productivity apps. Ha ha
Glad to meet you; the good part about being ignorant to things on the other side of the world, is that you can learn if someone is kind enough to teach you what you don’t know. Thankfully for me, you’re kind, and I learn quickly! Cheers #SemperGumby
Re: Dual-CAD Office
If you have a simple drawing -- typically a 2D .dwg file -- you can save it as AutoCAD R13 DWG and it will be "true DWG", because the true DWG signature was invented in R14.
- Ragnar Thor Mikkelsen
Norway
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That takes me back a few when I ran VersaCAD and one AutoCAD station just to translate the DXFs to DWGs. We also did it with LT and full blown AutoCAD for the one or two commands which LT did not have. Those were the days.
- Dave Edwards
Dave Edwards Consulting
The editor replies: Back then, we enjoyed the challenge, because it was all new.
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Recently I've been researching alternatives to Inventor. The reason: I need to do hybrid modeling which incorporates 3D scan and mesh data. I tried doing it with Rhino, but McNeel doesn't see the need to give us a few more tools to make it work with scan data.
So now I've narrowed my choices down to the scanner's native program ($7,000) or ZW3D ($3,000). IronCAD would be a good runner-up if they could process scan data. Otherwise, there are no other cost-effective solutions on the market that I've seen. Have you come across any good hybrid modelers?
- Chris Caman
The editor replies: Have you tried the latest release of Solid Edge? It now handles both types of entities.
Mr Cadman replies: I couldn't find any good reviews on Solid Edge, like the guy who shows how ZW3D works. So I just forgot about it. Too many irons in the fire! I'm prolly going to try ZW3D, based on all that I've seen. The mega corporations don't give care about their customers. At least ZW3D is 'showing face'. I'm jumping on this train just as it's leaving the station, so I can only hope!
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"A lot of pundits have a sense that automation is accelerating in replacing jobs. In fact, I predict it will slow down, because we have been picking the low hanging fruit first."
- Dan Hanson
marginalrevolution.com/marginalrevolution |
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