so i looked into options some more and had a question. it looks like the 3d coat retop to the viacad subd to nurbs might be a simple way to get a cold shape fea model back to a nurbs model. so it would go stl to obj to nurbs. but i'm not sure what 3d coat version has the retopo. can you use the cheapest one for 3d printing. or do you need at least the hobby version or higher.
viacad has a lot of powerful features packed into a terrible interface. so i'm not too keen on getting viacad. so i may not even do this. but was curious about 3d coat. i watched some videos about the retopo and i think it would be easy and fast to do. the 3d coat website wasn't helpful in figuring out what each version does though.
note; i just recalled that didn't moi add obj to nurbs? is that going to be a v4 feature. if so then i wouldn't have to suffer with viacad.
thanks for the tip. i'll take a look. the models will be pretty simple wing like shapes. so it's nothing fancy.
michael, if the stl file gets converted to obj. will moi then convert it to nurbs? i thought that's what i was reading on the forum in the past. now it seems like you are saying not to do this. so i'm confused
an earlier post suggested meshmixer. however, i don't see that it really converts the stl to a quad mesh. it will save it as obj but it's still triangles. seems like i need auto retopo? i'm not at all familiar with this stuff. so sorry for the dumb questions
re:
> michael, if the stl file gets converted to obj. will moi then convert it to nurbs?
Well it will, but it won't work very well because a triangle mesh which is what you have from .stl format is a different kind of polygon structure than one that is set up for sub-d smoothing.
For example, a sub-d control mesh should be formed of nearly all quads and not be very dense.
It's not really just a matter of just converting from one file format to another, the structure of an .stl triangle mesh is not the same thing as a polygon mesh that is set up to do sub-d smoothing.
Hi Anthony, yes if you additionally do that then you should be able to get a conversion.
I was just going by what you wrote: "michael, if the stl file gets converted to obj." , I was taking that to mean just .stl triangles converted into .obj triangles.
But I'm still not entirely sure that this process will be suitable for your particular needs - auto retopo is not focused on accuracy really at all and isn't going to try and match a particular tolerance value. The processes that uses it are more oriented around just rendering and visual artwork, not on engineering.
thanks it's making more sense now. looking at prices and features of various products still. 3dcoat seems to be a lot cheaper than zbrush. i watched some viacad and 3dcoat videos. in the 3dcoat video i can see what you mean about tolerances not being that close. it seems like the main point of it is to shrink the mesh. i think in the viacad video he mentioned tolerances and did a check for max deviations. but that was to the already retopo model. which like you said is rough.
i'm not really sure what i would want at the moment. it's more academic. i was just trying to figure out a workflow i could recommend to prop design users.
the method i was going to do was just use the stl as a guide to move the airfoil sections then re-loft. i'd still need to import an stl file. but that could be done for free with meshmixer. it would just keep the original triangle mesh from what i saw. it just saves that as obj.
so i guess i'm considering two different workflows. i'm not sure which would work better. i'd have to create models, do fea, etc... so that's a ways off.
i'm also trying to find something for inertial properties still. ashlar-vellum looks ok but it's pretty expensive. based on acis kernel so they probably have to pay a large licensing fee. viacad is very powerful but i don't like what i've seen of the interface. i'm done with rhino. so still looking on that front. i'll still keep rhino v5 because all my work for prop design was done in it. but at least i won't have to use it anymore. other than to look at an old model if i need to. i found that the dimensions weren't transferring to moi, when working with a forum user here. a lot of my files have dimensions in them. i can live without the zebra plot. so not worried about that.
can't wait for v4. counting the months. so right now i'm looking at moi, 3dcoat, and something for mcad. stuck with old keyshot too. all my prop design stuff is in that and unfortunately i can't get the same results with simlab.
anthony
i had one thought on the tolerance issue. since the parts are pretty smooth wing shapes. i would imagine it wouldn't be too hard to change the triangle mesh to a quad mesh. but maybe i'm wrong. they aren't lumpy faces and things like that. they would start of as moi lofts. go to fea. i find the cold shape. which is a slightly distorted version of the blade. then unfortunately that comes out as a triangle surface mesh. but it's still not too different than what went in. mostly it's the meshing errors. i guess if you didn't have a high mesh density it could be a problem. also for composite shell models i wouldn't need the retopo at all. that could just be converted with meshmixer. so i don't know. i'll have to think about it.
i used to use alibre way back in the day. i checked it out again and they have atom3d. that is their hobbyist package. it says it can do mechanical properties from a step file. that's what i need. it's not super cheap but it's the best option i've found so far. the interface looks a million times better than ashlar vellum or viacad.
looks like it has a nice interface. however, Atom3D is probably the closest to what I want in features and cost. I'm using Mecway for FEA. The developer said he is going to add inertial properties in the future. If he does that, I won't need Atom3D. So I'm going to wait for now. I found two solutions to convert a stl to obj without retopo. That may be enough for what I need. 3DCoat may not be needed. But if the hobby version has retopo I may check it out in the future. So I think I answered my questions here. Thanks to everyone for the input.
One interesting thing I found. Ashlar Vellum and Atom3D both use the ACIS kernel. But they are drastically different in prices. So Ashlar is just charging more for no particular reason. I thought it might have been due to high licensing costs. But that isn't the case. I think ViaCAD is also using the ACIS kernel. Same with TurboCAD. TurboCAD and Atom3D are both options. I've used both many many years ago.
looks like the low cost version of Atom3D will do this. however, you have to buy the expensive version of TurboCAD to do the same. I couldn't find any information for TurboCAD. I had to get in touch with them. So not really even sure how good it would do this task. There are videos for Atom3D / Alibre. Which show that it does the task well.
thanks. the us site hasn't been loading for me. but i talked to them and they daid only pro has mass properties. the weird thing is before i talked to them i looked in the user manual and they aren't mentioned
Direct modeling is cool and Fillet, Chamfer, Boolean some strong!
Moi to Shape is easy by SKP format inbetweener
Render of course SimLab Composer lite (free)
PS If you export as DAE to SKetchUP, seems there is a bug even both programs are in unity meter!
You must scale * 1000 in Shape before the exportation!
else you will have some faces no filled!
