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ChrisBZ

Subdivision not working ?

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Posted (edited)

Hi! New to the cafe and C4D and loving learning. Finding this resource is awesome!...

I've hit a brick wall and wondering if anyone can help?
I've added a subdivision subsurface to this car body, but it will not render - the angles remain sharp so the render looks worse than the viewport. I tried removing the bevel  and a few different approaches / settings and always get the same result. What am I doing wrong here? Please see attached images - one is the viewport before render, the other is after standard render. 
Thank you for any advice you can give! 
Cheers,
Chris

C4D car not rendered2.jpg

C4D car rendered2.jpg

Edited by Cerbera
Moved to correct section - re-titled for future search use

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screen grabs are too small to read any details in the OM, maybe a bigger grab of that area or upload a cutdown scene file.

Deck

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Curious. The subdivision for editor and renderer is set to the same value, so the resulting image should be the same. The Standard Renderer does not have render setting options to switch SDS off, either. There is no animation on the SDS, and the timecode for both screenshots is the same anyway. Doesn't seem obvious to me...

Please send a (reduced) scene file. In the meantime, what happens if you switch the SDS to another type?

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This is almost certainly something to do with OpenSubdiv settings, but unlikely to be a bug. Like everyone else here we need the scene file to be able to tell what is going wrong.

 

CBR

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Thanks for your responses. I have attached the C4D file, only the car model in there. 

I did try a number of different Subdiv settings but I'm a complete newby so am likely to be doing something wrong....

Thanks again, Chris

Car ex.c4d

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Oh it's to do with illegal topology. You don't seem to be aware that you can't use subdivision surfaces with triangles, complex poles or ngons and expect a predictable result - this is one of the primary rules of SDS modelling - you require an all-quads model, with even, regular distribution of polys and decent edge flow. Unfortunately this model has almost none of that, meaning that you leave it almost entirely to luck whether SDS works or not, in this case it doesn't, and can't until you fix the mesh !

 

image.thumb.png.8b00b949ff7cde66fbaa8e8cf25d068a.png

 

In fact this mesh has some fairly fundamental problems, and is not nearly enough polygons to describe the form, and I'm afraid at this stage is eminently unsuitable for use with any kind of subdivision.

 

CBR

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Thank you for your feedback Cerbera. I did start it as a low poly project originally, and then just expected an SDS to work when I decided I wanted a smoother overall finish, now I see I'm clearly being naive!   

It's very early days for me so it's great to get such detailed feedback from a veteran.  I'll go again with the body.

Thank you

 

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ps for my own knowledge (and sanity) - why is it that the viewport looked nearer to what I wanted, but the render did not?

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You're welcome 🙂 Don't feel too bad - these are the sort of problems that everyone new to modelling must face at some stage, and it's good to get them out of the way early in your modelling career ! For your reference, cars are generally best made with a technique called patch modelling, which is very closely related to regular SDS Poly modelling, but with a few key differences.

 

Here is an example of a car made with stellar topology that will work absolutely flawlessly with subdivision because it gives the algorithm exactly what it wants to be able to work. Note the polygon density, the evenness, the regularity, and the lack of even a single triangle or complex pole...

 

image.thumb.png.7fffc88b0ab531f8cfcc1ad0d562890e.png

 

CBR

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🤯  This is truly a thing of beauty.  Thanks for sharing.

I wanted a more childish finish to mine (the overall scene is all very low poly in feel), but not totally angular.  I just could not understand why the viewport looked near to my vision but the render just wouldn't do it.

 

 

 

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