Sorry, what is GMD ?

GMD short for Geomagic Design. Others refer to it as GM. Used to be Alibre until 3ds baught them out. Not 100% sure about all the "politics".

Hello,

Using Blends and Fillets allows you to preserve some continuity between your surfaces and may end up simplifying them so you can tweak them a bit more easily. You might want to check out VSR/Autodesk tools for Rhino, and TSplines may be a candidate as well for this sort of surfacing work.

Thank you, Elrick.

When I checked the GMD website and looked for the price I only saw an email link, "Click here for a quote." Ugh, never a good sign for us hobbyists.

http://www.alibre.com/products/ad_compare.asp

around 2000$, 2000€, 1700£

Pleasure Mike! If your file arent too big I could try the conversion for you?

GMD's full package is quite expensive. But compared to Solid Works it aint too bad. I would have prefered to start this project in SW but yet again the budget. SW comes as one package I assume? GMD have quite some additional/optional software add ons. Choosing a package for your needs, keeping the prices low. The full package we got about three years ago included Alibre CAM (which I use quite often on the CNC machine), Keyshot (low resolution) and MoI. Some very usefull functions are the assemblies, configurations and constraints. When you, for instance, want to see all the doors open or wheels out, you just activate a configuration. (Havent noticed this in MoI yet?) Works with other stuff like colours, transparency and exploded views too. But I would say GMD is more on the mechanical side of the CAD world. On their forum there havent been much support for these odd lofts.

Theres one other thing I tried but didnt work so well. Exporting slices from Mesh Mixer to Rhino as obj's. Tried both "Stacked" and "Stacked 3d". Then use Rhino's mesh2NURB command, which were very effective on the slices, and export it as an Iges. Not a very practcal way because this takes forever. Probably depends on the size of your mesh and the software youre trying to import to. The mesh of this fuselage I is about 8,4m long 2,4m high 1,7m wide. With a cell size of 0.5mm containing 2.6 milion vertices. So I probably were pushing my luck. When I tried to convert the full body/obj Rhino kept on crashing. If you have rhino you could try a whole body. But in fact this doesnt give you Nurbs. Sort of an exact nurb replica of the mesh. See attachment. This small part took about 20minutes to load. Part 10 of 168. When the files started taking longer than 60 min I realised this aint practical.

Hi Elrick,

"My main goal at the moment is to make a better 3d Pdf for online presentational purposes." I also read that you have already have a mesh.

Is the existing mesh not sufficient to make a 3d pdf?

Hi Chris,

Thanks for bringing this up. Yes you can bring them into Pdf. But in my opinion, the renders from the converted mesh looks bad in Adobe. And to make this hollow will make it look even worse. So that option is out for this purpose unfortunately. Cos it was an approach I hope would have worked!

Forgot to mention that I also need to make keyshot renders. (Lovely place to inspect surfaces! It shows you flaws you wont see anywhere else.) I am positive that the lofts from MoI would make very good surfaces to render in KS. Thats why Im here :) But after Michael s heads up I realized this wont be happening over night. I should start with small steps to make sure how to utilize MoI properly. Will buy it for my own personal use to learn after hours.

Elrick













Some related shots about topics.

How was the mesh that you used in the 3d pdf originally created ... from 3d scan, output from other CAD software, or other?

I measured everything as the project progressed with self leveling cross lasers. We bought a scanner from nextengine to help us achieve something more accurate rather than this "ancient" method. But I quickly realized this scanner is not the hardware for the job. After numerous attempted fails the salesman came over to show me "how its done". And he got the same results. After working in NextEngines software, Scanstudio and RapidWorks, my curiosity started with mesh work. Thats when I started experimenting with Mesh Mixer. Really awesome software! The meshes I use in MM are Stls exported from the solids redrawn in GMD. The fuselage were done my the hands of our technical manager.









Top picture, original mesh exported from GMD. Didnt touch the export parameters. Bottom picture vertical beam and tape represents the planes (Z values). Made dots on the tape to find my X&Y values for the profiles. Used another laser square the vertcal beam. Simple method but open for many mistakes. (Tried to maintain .5mm accuracy)

So the mesh was not from a 3d scanner, but from 3d points measured using photogrammetry?

What are you using MeshMixer for?

There is software such as AGI's Photoscan that can create a mesh exclusively from photos (no laser needed), if you have enough suitable photos, and automatically construct the model. I am just starting to investigate this technique as an alternative to laser scanning.

I need to do some testing to determine what tolerances I could expect from a set of photos. There are a few variables that can impact the quality of the model.

I think I misunderstood after reading your reply again, it seems you measured the points manually on the tape and plotted them in a CAD program?

"The fuselage were done my the hands of our technical manager."

Do you mean that all the surfaces (and molds?) are made by hand?

"What are you using MeshMixer for?"

I wanted to convert all the lofts into one body and smooth out the surfaces. On the edit tab there's a command "convert to solid" which I pushed to the limit. Some heavy calculations! After the conversion I smoothed it where needed and possible with "Deform> Smooth" on the "select tab". Works great! I was aiming for this years ago and were blown away by the effectiveness of Mesh Mixer! But converting these meshes back to something worthy seems to be a very big challenge for all the experts in programming. Rhino's user guide have some useful insight about this. TSpilnes as mentioned by OSTexo seems to be an alternative for this sort of work. I tried it for a short while but the results were a bit confusing compared to some videos I watched online. The only way seems to be GMD and MoI for now :)

"it seems you measured the points manually on the tape and plotted them in a CAD program?"

That is correct.

Do you mean that all the surfaces (and molds?) are made by hand?

Yes. The engineer and lead designer behind it, Wolfgang Vormbaum, knows what he is doing! But its impossible or would consume too much time to get these shapes 100% symmetrical by hand. Which is why I need make the most of all I have at my expose to get this right. The next aircraft we will be manufacturing will have this whole fuselage mold CNCd. Smoother surfaces for a lighter body and reducing turbulence. Also cuts down on man hours. In this evolving world anything which saves time and money is worth looking into right?


Just a matter of time before we start testing our prototype. The engine is made by a team located in Durban, South Africa. Adept Air-motive: https://www.youtube.com/watch?v=GVkV_VITXBY

Some old previews of the prototype could be seen over here: https://www.youtube.com/watch?v=dzMqrGDE0Y4

Do the lofts in MoI have the ability to use guide curves?

Elrick,

I actually use SolidWorks, but have been looking at Moi and Rhino for better surfacing tools. But a quick run through the Moi help seems to indicate a network surface in Moi might give you a bit better control if loft does not.

I have done a fair amount of reverse engineering work over the last few years, and now that I understand it, that is what you are doing with this hull.

If you have a concern over how faithful your CAD model is to the hand made form, then you also need a way to measure the difference. I think getting a good scan of the hull will benefit you by providing a reference for deviation analysis, as well as giving you a reference for the modeling process. However, I don't believe there is any way to go directly from the scan to a 3d cad model without a lot of work. Some high end programs like Design X (Geomagic) can simplify the process, but I have not seen anything like your hull produced with Design X. I would love to know how it would handle something like this.

I understand the Next Engine did not work well for you. Perhaps there is another scanner or service that might. Your part is large, so a long range scanner might actually work fairly well and give you reasonable accuracy. Some of the laser scanners that attach to digitizing arms like the Faro only scan about 1-1/2" swath at on time so it would take a VERY long time to do your hull that way. I work with someone who has used a Focus3D (also from Faro) to do body panels. I constructed the nose of a truck using the long range scan from the Focus3D as a modeling reference.

Hello,

Structured light scanning would probably work well for your application. I fuselage itself doesn't look overly complex, however you might want to plan out your model with a variety of techniques that will allow you to more easily change the different surfaces of a model more easily than loft. You typically have less control over surfacing when using loft as opposed to other surfacing strategies. It looks like there are several major components to this model, having a lack of control over surface modification if you need to make a change would be brutal if you lofted that entire model.

Hi Elrick,

> Do the lofts in MoI have the ability to use guide curves?

In MoI that's called the Sweep command, it can make a surface going through profiles and using either one or two guide rail curves.

- Michael

Is this a case where Sweep and Network Surface overlap in functionality, or is it preferable to use Sweep if you don't need more than 2 different guide rails?

For reverse engineering a bigger question is, if there are curves produced from a 3d scan or reference model, which surfacing tools will generate a surface that actually passes through the curve?

Hi,

Tried to keep it short but thanks for sharing all the advice and tips gents!

"I constructed the nose of a truck using the long range scan from the Focus3D as a modeling reference" - Do you have a place where you share pics? The Faro products seems very interesting! How many times did you need to move the arm's position for the measurements? How many days did it take?

"I actually use SolidWorks, but have been looking at Moi and Rhino for BETTER? surfacing tools" You are confusing me when you say this! :) Cos this --- http://www.raptor-aircraft.com/home.html --- made me believe Solidworks gives you everything in one package? Looks like SW do FEA calculations as well. Not too sure about the renderings but I believe Keyshot has this under control! :) We were talking about buying Rhino to handle the surfaces. I believe our next investment will be either Rhino or SW.

"If you have a concern over how faithful your CAD model is to the hand made form, then you also need a way to measure the difference." - At this time I have some freedom to make modifications to the original design. I had to cut the ribs for the hull with the CNC. (skeleton) My cut parts were spot on. This is where I spotted the small symmetrical differences.

"Perhaps there is another scanner or service that might." - A sales representative of 3Ds gave us a quote for a complete scan of the fuselage. He did some demonstrations with the Arctec and Sense 3d scanners. It might be an option for the future cos we wont be able to afford something like the Arctec (thats if we are really looking for reversed engineering tools). The quote is equal to 3 months my salary. So its better to continue with the data we already have for now. I did some turntable scans with NextEngine. The results were great! Its very handy for parts to be scanned by the table! But the accuracy is lost with single scans. Its quite an effort to assemble the single scans. And after the fusion the comparison were off by more or less 3% over a span of +- a meter. Didnt take me long to realize single scans wont work.

"having a lack of control over surface modification if you need to make a change would be brutal if you lofted that entire model". I fully agree with you on this! Making modifications in GMD is brutal! Because a 2mm difference in the guide curves makes a hell lot of a difference in the shape. Thats why I hope MoI will help us achieve our goals. We are talking about making a 4manned version and I would like to see if I could maneuver the lofts like Andrei did in his videos. His method seems good and the results of his rendered boat looks flawless. That way it wont be a hazzle to modify surfaces. There might be one problem and I hope Im not aiming of target here. My average control points through these profiles were about 22, which sounds like a lot? Will I need to make blue prints of the fuselage profiles and project them in MoI? Sounds like a lot of work but totally worth it if works.

Regards

 

 

 

 

Some related pics