Cineversity

Hi, I have a question concerning exporting and importing vertex normals in regards to Rod Ross’s tutorial series on Importing CAD Models into Cinema 4D. I noticed that many of the CAD models that were imported into C4D don’t have a vertex normal tag applied to the mesh. In fact, some of the export dialog boxes I saw in the tutorials had the “vertex normals” check box turned off. I was under the impression that the only way to get smooth mesh from a CAD model was to make sure the vertex normals end up applied to the final mesh in Cinema 4D.

To see one of the models in the tutorial series that looks smooth, but doesn’t have a vertex normal tag, take a look at Rod’s video “Importing CAD Models into Cinema 4D: Enhancing CAD models in Cinema 4D.”

If there is a way to get CAD models into C4D without needing the vertex normals, can you outline the workflow you use? Every time I try, the mesh looks terrible!

Thanks
-Randy

Hi Randy,

In this forum [Tutorial Questions] the question should be created by the “Help With this Tutorial” button, left sided to the clip, to keep things organized. Any other question should be in the Q&A forum.
Do you have an example, where you are not happy with? Please only the single model in the scene, nothing else, c4d file, so I can see what you got. If you need an upload link, please let me know.

Have a look at the Vertex Normals and perhaps it gives you already a clue:
https://help.maxon.net/#DBASEDRAW-BASEDRAW_GROUP_DISPLAY

All the best

Hi, Sassi! Yes, I tried clicking the help with this tutorial button, but all I get is a blank window in Chrome and Firefox. I will take a look at the link you provided. Thanks

-Randy

Hi Randy,

Sorry about that experience. (Edit, it seems to be fixed already, please let me know if it doesn’t/edit)
I checked and yes Chrome gives me the same problem, well - since I don’t use this, I just checked Safari and the same problem. So, I’m sorry to have requested it. I hope tht will work soon again.

My understanding of your target is to know how to get the model in C4D in the best workable way, smooth. Rod Ross showed some typical ways, e.g. Bevels. As you certainly know, CAD has not really a need by default for this. Given architecture models, that would limit even the precision for material calculations if they would shave up a bevel all over the place ;o) speaking of volume calculations.

I will set up an upload link and send it to your PM box, if you have no interest in it just ignore it.

All the best

Sassi, I used your dropbox link to send you a file. This is a client’s model, so please don’t share on this forum. Would it be better to contact Rob Ross about this? Is that possible?

Anyway, I am wondering how he is importing smooth mesh from CAD models without having vetex normals passed along in the export/import process. You can see in my file that the mesh with a vertex tag is smooth while the mesh imported without is bumpy.

Thanks
-Randy

Hi Randy,

Switch the “lines” mode in the editor view, the mesh is different, well very different, in each model.
There is a little bit more going on than just normal definition/information during export.

Ross discusses the re-meshing in ZBrush, perhaps a good idea as well for this one.

Thanks for telling me about the client file, I will not show it anywhere.

I have of course send a PM to Rod Ross. I hope he gets a notification about it.

Your model in detail:
Each version has some problems.

If you go to the Attribute Manager>Mode>Modeling>Mesh Checking, you will see a lot of problems right there.

Especially the amount of bad polygons Bad model: 99 Good model: 19 (Since I can’t show it here bad and good were the two names of the model)
You can select them and work on those, the optimize options takes a nice load from that work away.

There are also areas, where it looks like the mesh is not connected, but there are super long, very small polygons between the larger areas, which leads to a significant low quality appearance while rendering. Perhaps the settings while exporting the model should be less aggressive (I guess the degree settings) and a lower polygon model might be much smoother.

If I check the Normals (poly and vertex) this seems OK, considering that the polygons are not really.
All in all, this seems more something on the creator side than on the import side.

https://www.amazon.com/clouddrive/share/qs8x5CFLB6i2uufFZyUHdFp6RzoOur6wgOAryOqzSAl?ref_=cd_ph_share_link_copy

All the best

Yes, doing mesh checking on an imported CAD model will show all kinds of errors. Those errors don’t matter if I get a great still rendering in the end. I am getting great still renderings when I import models with vertex normals. My question, specifically, is how Rod is importing CAD models without vertex normals and getting a smooth mesh. The models would be easier to work with if a vertex normal tag was unnecessary. Perhaps he is getting the tiny blemishes in the mesh that I got and it is okay for his use.

I sent you a file named “vertex normals question 2 both from Rhino.c4d.” You can see that the structure of the model is the same in line mode because both meshes came from Rhino. Only difference is that one has a vertex normal tag.

-Randy

Randy,

The previous where certainly very different, see the image that I have attached.

Yes, the new [v2] is identical to each other, so far I can tell.

Do the following: CMD-Drag [copy] the Vertex Tag to the “Bad” version, render. Looks the same, doesn’t it? OR do I miss something? (This wasn’t possible with v1.)

Without that tag the average middle point in each Polygon is used to determine the Normal position and direction. This will be used, with the Phong Tag settings [break phong edge incl.], to create the smooth calculation. Phong as it was used back in the last century already.
If there is a “Bad Polygon” [e.g. corrupt], this will go with the try to get a normal there as well. Normal to normal.

NOW, with the Vertex Normal, this is a complete different story as each polygon is seen not only from the mid point Normal, it is seen as well from Vertices. A much more precise calculation of the smoothness—or not at all is given.

In your model, in v1 and v2 are bad polygons and they create your problems.
I have take very tiny areas, the object is not recognizable nor identifiable at all in this one minute clip, but you can see by selecting according to the vertices numbers [Structure Manager] that the result you got from your CAD is not OK. The Vertex Normal is just camouflaging it. That’s all. They help to keep it smooth where the geometry and its Normals would tell otherwise.
The one minute movie clip waits for your OK to be posted, the link is in your PM

Again check the angle of change (no idea how it is called there, but it is build on the ACIS engine, if I remember correctly) as the export parameter in Rhino, and it works from a math defined object via angle derivation to a polygon creation. Straight forward stuff.

What was done in the tutorial and how each model was treaded is not to my knowledge.

All the best