3D Principles
  • So for c4d I'm doing fxPHD training, reading the manual and looking at some tutorials..

    Feel like i'm progressing along ok, BUT I do feel like I'm lacking principle 3D theory.
    It's all well and good knowing exactly how to use specific tools in cinema there are things that I feel like I should know, some things I've found out by googling, some I'm still not 100% clear on.. things like:

    • In detail: When are quadrangles, triangles or N-gons better?
    • If I'm using the kinfe tool to model things, where should I cut, to an existing vertice if possible or is it ok to just make new ones where it suits?
    • Other than just flipping the normals of an object and seeing what happens, why and how should they be aligned?
    • I know Phong, Blinn etc are better suited to different materials, but how and why?
    I'm not asking you guys to answer these questions, it's more that I know that for everything that i'm aware I don't understand fully there's probably 10 things i'm doing wrong ignorantly.

    What i'd like is some good 3d general theory.. In the form of a book, website, video, whatever. Just feel that my current training is preparing me for various tasks but not giving me a good underpinning. Anybody got any good resources?
  • I know @odd_enough is our resident 3D guru, but maybe @eyedesyn and @Rostenbach can help too.
  • Here we go! I've been itching to write up an article on this kind of stuff for awhile, but.. like everything else, I don't have the time. But I can take a small break to answer some of these for you. :)

    So first question, when are quads, tris, or n-gons better? Um, first off, n-gons should ALWAYS be your last resort. Hell, if you end up with a 5-sided poly, It's best to split it into a quad/tri than leave it as an n-gon. I have heard of some people saying that pentagons actually work when subdividing, but I've never come across a situation where that was acceptable. 

    When modeling anything that you intend to drop into a NURBS or want to subdivide, you will want to model strictly in quads. The occasional tri is acceptable, though. How do you know if a tri works or not? Good way to tell is drop your base model into a NURBS, and if the normals look good (all smoothed and no funky artifacts), then you should have no problems sub-diving further. I have yet to come into a situation where an all-quad model returned surface errors when smoothed. Even if the base model looks wacky, it should work.

    As a note to NURBS and SubD: Use supporting edges! when making supporting edges, make sure the loops go ALL the way around the model. making a cut on a single poly will produce n-gons. And NURBS hates n-gons. Yes, it will produce a lot of extra geometry. Better that than funky normals. 

    I guess this eases into the knifing question. When making cuts, you can honestly cut wherever, as long as it suits the form that you're trying to produce. If you create n-gons, be prepared to fix it, or make loops from the get-go. I will admit, getting out of the habit of using n-gons took me awhile. They are easy and quick, but they produce bad results. You just kind of have to force yourself out of it. I will try to do a write up on anti-n-gons in the future. 

    This is all the time I have today. Will answer the rest when I get home. :)

  • Awesome, thanks!
    I did come across some weird bits when hyperNURBSing some of my stuff and now that I look at it there are lots of triangles in there.. Does it matter if a quad is not planar? Because I think I made a few of those triangles because it felt wrong having quads that were sort of bent, so I chopped them across the diagonal.
    Ok, that makes sense, I never really knew why people seemed to often cut loops when they didn't seem needed, now I know!
  • No problem :)

    So, normals. Are you asking about smoothing groups? Like when to break the normals and when to unify (based on smoothing angle)? Normals are interesting. Currently the workflow I take with normals in video games are probably only slightly different than film/mograph. Probably won't be using many textured normal maps in mograph than as you would in games.

    For important, or high visual objects, I put all of the normals into one unified smoothing group. Reason for that is, if you have a textured normal map and you apply it to a model with more than one smoothing group (groups of normals smoothed at different angle thresholds), they conflict and screw things up. That isn't to say you can't or shouldn't. You just need to plan and/or use best judgement when creating your smoothing groups. 

    Honestly, for mograph, I rarely had to think about normals much. I wasn't doing any fancy tricks with them, or using normal maps. I mostly just applied a 45 degree smoothing angle to everything to give it a generally accurate look. :P If I wanted a lowpoly-look, I'd set the smoothing angle to 0. 

    Right, so Phong, Blinn, Ward, Oren, Lambert, etc..

    (when I used C4D r11-12, I could never select Ward, Oren, Lambert, and others. I guess they weren't available?)

    I'm honestly not sure of the technical aspects of these spec types. I just know that they are different methods for calculating specularity. Phong and Blinn are good for plastics and some glass, while Ward is anisotropic and good for metals. Lambert is your general matte shader with a high roughness, low reflectivity. Oren is usually used for rough surfaces. Also, Phong and Blinn have pretty good highlights (or rather, controllable highlights). 


    Let me know if there is anything here that you might have questions about (not sure If I made them more complex for you than they already were). Or if you have any more questions about anything else. Cheers! 

  • Cool, thanks, I really appreciate it..

    I definitely need to look into this smoothing group stuff, can't say that I know much more than what you've just said but you've sent me in the right direction anyway!

    Yeah I only know off Phong, Blinn and Oren-Nayer.. Guess just a case of experimenting.. Going to refer back to this post the next time I'm trying to  make some new material (which I really like actually, especially the whole procedural thing, using different types of noise and shaders is fun.. Made beer with foam and everything the other day)

    Will definitely be posting again if (when) I come across some more questions!
  • I should also direct you to the Polycount wiki entry on normal maps. That entire wiki has been one of the most helpful resources I've found when learning about 3D asset creation. While, a lot of it has to do with game asset creation, it can also be applied to VFX. Tons and tons and tons of excellent information!
  • @odd_enough .... That.. is.. brilliant... 
    This is the clearest explanation I've seen and it goes into detail that I don't need yet but maybe will someday!

    Thanks!
  • Oh, while I'm at it, anybody got any good resources for explaining how to make stock models not be.. well... shit?

    As in, a process or best practice thing.. I've just been sort of fudging it. Do need stock sometimes though, have taken a few from google warehouse and then always end up giving up after messing around with them for a few hours, basically then modelling them again from scratch..
  • Do mean mean how to go about cleaning them up? That's always a pain in the ass. I've been forced to get better at that ever since we've gotten interns in the office here. They'd hand their "finished" models off to me and I'd spend an hour or so cleaning up their mess, and then a few mins after lecturing them about the need to make clean models to begin with. I guess the same goes for stock models =/

    Erm.. I think it first takes a good understanding of modeling on your own in order to become comfortable with cleaning up someone else's model. Because you don't really have any documentation available to you on how they modeled it, and why they did certain things. Just like uncommented code. Though with modeling, if you understand the methods, you can eventually pick it up with ease. Though there are times, I see a model and think.. "what the FUCK did they do to get this?!" 

    I understand that people use stock models because they are short on time and/or don't know how to do it themselves. Hell, I used to do that. But I got fed up with wasting money when I knew I could learn and get the model for free. It just meant that I had to spend some serious time to work through learning how to model well.

    The trick? Practice, practice, practice... and more practice. Just pick a ton of really easy objects, and model them until you get into a routine. Then pick a little toucher objects. And so on. After modeling ~80 or so simple objects (restricting myself to quad-only), I was moving on to complex car parts with no trouble at all. Hell, the routine mentality works for just about anything. The same went for UV unwrapping for me. Was, by far, the most annoying aspect of 3D to me thus far. And now I can UV at ease.

    Sorry for the long-winded post, and I know you didn't ask about some of that stuff, I just figured might as well share as much info as I can, regardless. :)

  • Yeah I'm kinda thinking along those lines myself.. Just volunteered to do a project that was going to be outsourced as was a bit too advanced for what we do. Building a castle scene with surrounding countryside, detailed closeups and interiors for a big camera sweep through with a heavy (night-time) grade on it. Should be interesting, gonna try to make as much myself I can within the time limit (around 6 days for the whole thing :/) 
  • @JamesDohertyEsq Budgets are one of the main sticking points to me learning to model properly. When there's not much budget and only a week to finish a broadcast spot, there's not much room to play, so we end up buying models. I hate it, but I understand the motivations behind it. Either we pay a couple hundred for models pre-built, or a disproportionately larger chunk of the budget is spent on my doing it and learning along the way.
  • @jamesDohertyEsq @conigs @odd_enough yeah budgets are a killer, why spend like 2 days worth of the budget when you can buy in something better? (especially with less time at home for polishing up...damn kids!) 

    James/Jordan I dislike having to clean up stock models, especially turbosquid vehicles. And google warehouse.. Oh dear. I don't think I've ever used a model from there without having to do serious work on it. I love it when a model is composed entirely of duplicated, disconnected triangles.


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