Hi everyone,

I have just spent a good few hours playing with KeyShot v3 as a possible rendering solution for my needs. I have come over to MoI to get away from Rhino, and to possibly leave Windows too. I was just thinking I had made it after playing with KeyShot and importing iges and obj files, and then i spied in the list was Rhino *.3dm - Yeeeha ran through my head, but alas KeyShot won't import from MoI, it keeps nagging about wanting the view set to shaded before saving from Rhino.

I have tried everything I can find in the MoI options associated with views, lighting, and using solid colour and no styles but still can't save a file that's KeyShot happy. As i have said, I can export and import using different formats, but I don't just want my cake and eat it, I want the cream too!! Can anybody tell me if it's possible in MoI to have what KeyShot is after regarding shaded view settings.

Many thanks ...

Martin

Hi Martin - the problem is that Keyshot only reads render mesh data from the 3DM files, it does not try to process the NURBS objects directly.

That means that it will not work with 3DM files saved from MoI - MoI will only ever store plain NURBS objects in the 3DM file, unlike Rhino. Rhino tends to be pretty slow when calculating its render meshes for doing a shaded display, so when it finishes calculating them it will store them as extra data in the 3DM file basically attached to the NURBS objects. That's just a kind of data caching mechanism used by Rhino but a few render programs will only look at that render mesh data only and not try to deal with the actual NURBS objects themselves.

MoI does not try to store any additional render mesh data in the 3DM file - it doesn't have to since MoI has a very quick display mesh calculation compared to Rhino and the display meshes can tend to bloat up the file size by quite a bit so it's not great to store them in the file if it is not necessary.

If you are in Rhino and do a shaded view (instead of leaving a wireframe view only), it then calculates render meshes at that point and that will have a side effect of storing that render mesh data in the 3DM file (unless you do a "Save small" from Rhino - that's another reason why it's not so great to depend on this particular piece of data since Rhino does not necessarily write it all the time either itself). So that's what that nag about shading in Rhino is about. But none of that applies to MoI, MoI will never store cached render mesh display data in the 3DM file no matter what kind of display you do in MoI. That's actually a nice feature of MoI that it does not need to bloat up the files with that extra cached display data in them.


So anyway, you might want to contact KeyShot support, and ask them to do a more thorough job of supporting the 3DM format and to actually read and process the real NURBS objects inside the file like they do for other CAD formats like IGES and STEP, rather than only trying to do this Rhino display data cache type shortcut.


Until then you can still use MoI in combination with KeyShot, it's just 3DM format that won't work. Instead I'd recommend using OBJ format for transfer from MoI into KeyShot - in the MoI mesh options that pop up set the option for "Output: Quads & Triangles" instead of the default "Output: N-gons" because I don't think KeyShot likes to handle complex n-gon polygons (polygons with more than just 3 or 4 sides). But if you set "Output: Quads & Triangles" it should transfer to KeyShot just fine.

And actually even if 3DM NURBS were fully supported by KeyShot I'd actually still recommend using OBJ format anyway, since when you do that you end up using MoI's mesher to produce the polygons and MoI actually has a particularly nice mesh generation mechanism.

So it's probably not particularly any great loss to not have the 3DM NURBS import working anyway, you are most likely better off using OBJ format which is the main method that you would want to use for transfer right now anyway.

3DM NURBS format transfer is more valuable for programs that are more focused on dealing with the NURBS models directly like another CAD program, not so much for rendering programs. The first thing that rendering programs do when reading NURBS data is to convert it to polygons and then usually throw away the NURBS data anyway since they are usually only focused on dealing with polygon data. So if you're targeting export to a rendering program, exporting polygon data from MoI is a better fit for that type of thing anyway.

Hope this helps explain what you were seeing.

- Michael

Hi Michael - Excellent answer as always, and one that certainly clears the speed difference between MoI and Rhino. It does also beg the question as to whether you could do a plugin or another export option for MoI to output the render mesh, IF that's a possibility, then can i ask for it to be added to the wish list... I will also have a query with the developers of KeyShot and see if they have any future plans.

Thanks Michael

Martin

I use KeyShot with MoI and the two programs play very well together. Output as OBJ and use Quads & Triangles as Michael recommends.

Just make sure you have assigned a unique color (Style) to each surface or solid where you want to assign a unique KeyShot material. The Style names you assign in MoI will come across into the KeyShot Scene Parts Tree, making it very easy to assign materials, show/hide parts, etc.

Ed

Hi Martin,

> It does also beg the question as to whether you could do a plugin or another export option for MoI
> to output the render mesh, IF that's a possibility, then can i ask for it to be added to the wish list...

It's not a very easy fit for MoI to include an option for that because another difference between MoI and Rhino is that MoI differentiates between a "display mesh" which is one that's created for the realtime display and has an emphasis on being created very quickly, and an "export quality mesh", which is what you get when you save to a polygon mesh format.

The export mesher has more of an emphasis on quality and will do some much more time intensive calculations and also has a UI that pops up with it to allow you to control the meshing process.

If I were to just add an option to put display meshes into the 3DM file, the renderer that then used that would be receiving only the polygon data that was meant more for the realtime display. And if I instead tried to put an export mesh into the 3DM file that would involve popping up a mesh options dialog and additional mesh calculation for every save to 3DM format even though MoI itself would not use that data at all.

So either of those is pretty awkward. I don't see how it would work very well to add that in, it's not a great fit with how MoI functions. Really that particular 3DM data should be considered to be just a cache of Rhino's own display data and other programs shouldn't really be trying to use it directly as the main method of data transfer. It's basically relying on a side effect of something that Rhino itself only calculates and stores under certain circumstances.

- Michael

What you go and do that for, Michael - I am more confused now - lol, and it would not be fair of me to ask you to describe the difference between a NURBS render mesh and a polygonal render mesh, I will however offer my thanks for taking the time to tell me why it's awkward, and settle for the reality that is MoI can export what i need to get a job done, and that's all it needs to do to be honest, anything else is pure icing and cream, so keep dishing up those ingredients and i will stay loyal to the product. :¬)

Martin

Hi Martin, well it's more like one is a "realtime display mesh" meant to be used for making a shaded display while modeling inside of a 3D viewport. It's overall tuned just for that purpose and takes some shortcuts with the mesh construction.

If you want to do something more "permanent" with the mesh like use it to produce a rendering or 3D print or something like that, then that's what the export mesher is for, it produces a mesh in a more careful way to make it have a higher quality structure.

The higher quality export mesh takes longer to calculate than the "realtime display mesh" - that's one of the reasons why there are 2 different mechanisms, because when you are just doing modeling you probably don't want to wait around extra time every single time you do any kind of model edit. So it helps make modeling have less hiccups just in your general workflow for the meshing there to be prioritized on speed.

So it's not that one is a "NURBS mesh" - it's that one mesher produces results more quickly but messier, and the other produces polygons more slowly yet higher quality.

If the mesh is going to be used for some kind of more involved operation like producing a final quality rendering, then that's when the "slower but higher quality" mesher makes more sense to be used.

If the mesh is going to be used only for the display of stuff on the screen while modeling only, then that's when the "faster but messier" mesher works better.


- Michael

i also use moi & keyshot on a mac, export to .stp and import
into keyshot with the old importer. tessellation will be done by keyshot
and you get smooth surfaces, plus all your defined parts....

Just tried that here but it failed to import, Keyshot says no geometry, strange the file is almost 80mb - lol .... Obj stays the flavour that suits, for now.

Thanks for the info though schneich

Martin

it works! you must klick on "advanced" and select "old importer"...
also i use keyshot version 2.2


cheers


t.

This is version 3.099 and i did click advanced and old importer was selected but it still said no thanks. It's not a biggie, OBJ will do

Martin

Edited 16.08.2012 - Iges import does work in version 3 too. However, you should not use the old importer and when exporting to iges file, you will need to hide or delete any curves or Keyshot will bomb out with a "no 3D geometry found" error.

Hope this helps anybody else with the same problem ....

Martin

good to know...


thanks


t.

Hi Martin,

The current KS Version is: 3.3.15

Hi Ralf, thanks for the message, yes 3.3.15 is the latest release but it has nothing added to it to be of any value to me to install it. If it aint broke don't fix it applies to me. Plus it's not my copy (yet), and I need more time than Luxion allow to test things because i actually spend the vast majority of my day having to take care of my disabled wife. Sadly most companies don't take these circumstances into account, and that does sadly include MoI, but a 200 quid gamble with MoI and it's excellent support from its users and from Michael is far safer than a 2000 pound gamble with Luxion when they cant even answer a question about how come they can interpret IGES NURBS, but not MoI/Rhino ones. So for now Keyshot is experimental to me at this time and is likely to stay that way until i can afford the gamble or until my friend wants his back.

Martin