Danny -

You can both view and download the PDF version of the tutorial here:

http://1drv.ms/1PNsXpQ

I updated a few images for clarity.

Ed Ferguson

Keith -

Here are my settings:

When performing the Subdivision step, set the slider to 100 and do not check High Quality Mode.

OBJ file format export settings from MoI:



If you post your 3DM file I can see how it looks in my render program, KeyShot. That can help isolate to either MoI or the render program.

I did see some minor ripples in my model early on, but not sure what caused them or why they went away. I strongly suspect some points may have not been in a straight line and the zig-zag caused ripples. Look at your points in all views and make sure everything is smooth and simple.

Also, do not use High Quality Mode when subdividing. My model looked the same either way, but suspect it will have (at least for my model) a better mesh in normal quality.

Ed Ferguson

Thanks Ed.

-

Hi Ed
Thanks for helping with this. I cant understand why I can get a smooth surface if I loft everything but get a lot of bumps and tears when I don't. Sometimes in Carrara I have found the vertices don't line up and that causes a black line when rendered. I don't think this is happening in this case as this is all one smooth object except where I have blended the windows. Both Carrara and Daz have smoothing options that make things worse rather than better.

I used the same output settings that you posted. At first I thought it might be because I selected too too few polygons.

Keith,

I'm not the expert on this but I'll tell you what I think :)

First, it would be good to have the model before it was subdivided so I could experiment with the structure. Not having that, I rendered the subdivided model:



I think the issue is caused by the roof line at the top of the windshield (top arrow) being pulled way back.



If there was an additional Split added on the door (at bottom arrow), and the split at the roof (top arrow) were not pulled back so far, I think it would render fine. My basic structure (before refining) is below:



Ed Ferguson

Unfortunately I saved over the pre-subdivided model. I'll have a go again and see if I can get a better result following your advice.

I did a bit of an experiment and for me loft seems to produce a smoother outcome. Both look fine in Moi but the loft export seems to be better.





The subdivided car always seems to have some artifacts even when I put the poly count to the limit and try smoothing in Carrara.






Whereas while the lofted car is not perfect its noticeably smoother. I think it might be something to do with surface normals?




I have learned a lot from your tutorial and the help you have given. If I ever manage to make this car Ill post it to this thread if that's OK.

I attach the pre-subd version of the one in the picture at the top of this post.

Keith,

I brought your model into KeyShot and it looks really smooth. I don't see any anomalies anywhere.

I'll have to defer to the experts as to why it doesn't render well in your program.

Your loft looks pretty close to the SubD version. I tried lofts before Max's scripts were available. I'd say making changes to the SubD structure is a lot faster (for me anyway).

Hopefully someone will have an answer for the render issue you're having.

Ed Ferguson

Hi keith - I tested your model and could not reproduce the anomalies you show using Cinema4D. Most likely you are not getting the proper vertex normals over into Carrara and it is instead having to try and generate the smoothing from the polygon data rather than the shading coming from the original NURBS surface normals which is what you want to have happen.

I guess the first question is what file format are you using for the transfer, is it possible you are using .3ds format? If so then that's the problem - .3ds is a kind of antique file format that does not support vertex normal data in it. Instead try using .obj format and make sure any option for importing normals from the .obj file is enabled.

I tested your file above carSubbed.3dm, and I exported an .obj file using these settings (I cranked the slider all the way to the right and put in a distance value of 0.25 to just force some more divisions on some slightly long and skinny polygons to get more regularly diced up sizes which can be helpful:




Then importing that into Cinema4D and rendering it I could not find any evidence whatsoever of those anomalies:




So I think it's likely that you are not getting the good vertex normal shading data coming over into Carrara. Make sure you are using .obj format for the transfer, check any import options to see if importing normals is turned off, and another thing is to make sure you are doing a full render and not just worrying about anomalies you see in a real-time display versus a full render.

- Michael

Hi Michael
This car http://www.turbosquid.com/3d-models/3d-model-2015-audi-tts/888350 is made of 114,688 Polygons and 126,510 Vertices. With the settings at Moi export settings at max and divide larger than 0.25 I do get a smooth Subd car but the body is now 45,866 polygons and 49,963 vertices, which seems a little excessive by comparison.

Using an evaluation of Keyshot I have found that a lot of the issues that Carrara throws up disappear and those that remain are due to poor modelling. Moi is wonderful and works really well with Keyshot (and many other renderers, I don’t doubt) but it is not very easy for me to use it with DAZ3’s products. I will continue my experiments for no other reason than I’m dogged and it seems to me it should be possible to make something that looks lovely in Moi and have it look equally good in any software that imports obj files.

I think Moi has spoiled me as the creative process in Moi is so much fun that it really frustrates when things that seem should be simple in Carrara turn into a grinding episode of trial and error.

Thanks for your helpful advice as always.

Hi Keith,

I'd think that it would be possible to get things to work well with Carrara. The last time I checked it, it seemed to be capable of importing vertex normals using .obj format.

But I will need a little more information from you in order to try and help you.

Are you using .obj format for the transfer into Carrara, or some other file format type?


> but the body is now 45,866 polygons and 49,963 vertices, which seems
> a little excessive by comparison.

It's really still so minimal that it's nothing to worry about. You might start to get worried about polygon density once you are above something like 500,000 of them. At around 50,000 vertices that's really not much to deal with on today's hardware. Maybe 20 years ago it would have been something to sorry about, but by today's standards that's really pretty small still.

- Michael

Here are the import settings. Apart from a few experiments I have always imported as OBJ.

Hi Keith - it seems like Carrara may have regressed in import functionality from previous versions, I don't remember having problems with I think it was Carrara 7.

I don't see anything that you'd set on that import options, but I did find this discussion thread here with someone else discussing a similar problem:
http://www.daz3d.com/forums/viewthread/48202/

The part of particular interest is:
"looks like theres also a on off switch “smooth” which turns of the auto smoothing and uses the the original obj data"

So try going to the "surfaces" pane and try flipping the "smooth" switch to the opposite value - it seems that by default it ignores the imported normals (which are the ones you want to be used for the shading), and instead calculates its own ones by averaging polygon face normals, that is what will lead to shading artifacts. Hopefully with that behavior turned off and the original normals being used you will see those artifacts go away.

Also in that thread is is mentioned: "Normals aren’t stored in Daz studio either, they rely entirely on the smoothing angle." - if that's true then I'm afraid that means DAZ studio just won't work properly for rendering CAD data since it is unable to use the vertex normals that are stored in the file.

Hopefully that surface option will fix it for you - it seems unfortunate that this used to work more easily in Carrara and seems to have become problematic in recent versions.

- Michael

Hello ed,

Great tutorial, excellent work.

French translation done! :)
http://moiscript.weebly.com/la-voiture-de-ed.html

Thank you Pilou! That must have taken some time. And you have nice shadows for the images.

Ed Ferguson

@ Ed
Thx to you for a so detailed tutorial!
Now it will help more easily also some Frenchies people! ;)

After a bit of experimentation I have found that I can edit the smoothing of individual parts of the model in the vertex modelling room of Carrara. While I suppose it all adds to my knowledge base its a tedious process. I gave Keyshot a try and the results are about a 100 times better without any fiddling about.







Thanks both for your help:)

Hi Keith, well that's a shame that they've made it more difficult to bring in CAD data into Carrara without jumping through some hoops. I'm fairly sure that in previous versions of Carrara there were no special steps needed, it just used the vertex normals that were provided in the file like you'd expect and like most programs do.

Just for my future reference in case someone else asks about it, where exactly do you go in the vertex room interface to enable the original imported vertex normals to be used?

- Michael

Hi

The edges that need to be smoothed appear as blue lines. When selected they turn yellow, as opposed to blue for any other part of the mesh.





Once highlighted select Smooth Edges from the model menu and use the default setting.




This is the result:

Before


After




I imported a ready made DAZ model that dates from 2007 and either it was not as well made as I remember or it came with some ragged parts. Maybe I'm being a perfectionist?



I don't suppose anyone has a method of fixing the problem before importing teh obj to Carrara such as a script of a work around involving passing the file through another program? I tried passing it through Hexagon with no luck.

Best regards
Keith