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Xoliul polycounter lvl 14
Hi guys,

I've recently added an article section to my website, since I enjoy writing stuff and it saves me some trouble having to explain certain stuff over and over to people.

First technical one I wrote is about RGB colormath, meant for artists who are starting to work with shaders. Be it nodebased or plain code, it´s supposed to explain some of the very basic principles of doing math with colors. People working with the Unreal 3 Material system for example, could benefit from this.
Do note it is very low level: a lot of people who frequent this section of Polycount probably already know this. Still, their feedback is appreciated, as well as suggestions on where else I could post this.

I plan to write another one in these series, about basic 3D and shader math: dot products for fresnel, diffuse, blending functions, masking, etc... That one will be a tad more advanced.

There´s also one on AO baking but that is probably well known for everybody who comes to PC.

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  • [HP]
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    [HP] polycounter lvl 13
    Very nice man! :) AO article is useful, and the RGB is informative! :)


    You should get these onto the polycount wiki.
  • Slum
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    Slum polycounter lvl 18
    Cool article, hopefully it helps someone. :)

    I think one thing that artists (especially starting out) don't realize, which keeps them from understanding things on a technical level, is that graphics on a computer is just a bunch of math. To get different effects or blending, you're just doing a bunch of math.

    Once you kind of detach your mind from the abstract ideas of 'textures' and 'colors',and realize it's all just a big bucket of numbers, it's a lot easier to understand.

    For example, terms like "additive blending" can be kind of confusing or just abstract at first . You may know the result you get when you use it, but not entirely understand how it works...which is something as simple as color + color.
  • Minos
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    Minos polycounter lvl 16
    Very nice, thanks for sharing!
  • Mark Dygert
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    Hey, those are great. Slums right info like this really helps break down some of the weird rules and methods we have to use. Thanks for writing it all up and sharing =)
  • Target_Renegade
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    Target_Renegade polycounter lvl 11
    Nice, thanks for these!
  • Xoliul
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    Xoliul polycounter lvl 14
    Slum wrote: »
    Cool article, hopefully it helps someone. :)

    I think one thing that artists (especially starting out) don't realize, which keeps them from understanding things on a technical level, is that graphics on a computer is just a bunch of math. To get different effects or blending, you're just doing a bunch of math.

    Once you kind of detach your mind from the abstract ideas of 'textures' and 'colors',and realize it's all just a big bucket of numbers, it's a lot easier to understand.

    For example, terms like "additive blending" can be kind of confusing or just abstract at first . You may know the result you get when you use it, but not entirely understand how it works...which is something as simple as color + color.

    Exactly. I really wanted to break it down in such a way. Hope I succeed in this, I really tried to keep it clear with the images and all.

    Thanks to all the rest also for the good comments!

    About Polycount wiki: how would I do that? Add a link in there somewhere?
  • Ott
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    Ott polycounter lvl 13
    I like your AO tutorial, I just wish you had images exactly explaining to people how to set some of the stuff up. It took me awhile to get all the steps down so they are easily burned into my brain, but for a noob telling them how to do a lot of your steps can get really confusing.

    Once I started using MR as my AO renderer, I haven't looked back. Used in conjunction with Crazybump's sexy specular via normal map settings, you have some killer AO if you know what you are doing.

    Something you suggested did stand out though on Method 3:
    Create a white material. Set it to 100% self-illumination. Now add an Ambient/Reflective Ambient Occlusion map into the diffuse slot.

    Render a Completemap element to texture.
    As far as I know, simply assigning the diffuse as AO and then rendering-to-texture a diffuse map negates the need to set self-illumination or make it white. It should be all of that by default and work correctly. Don't forget to turn Shadows on in the render-to-texture. I always forget that :poly142:

    Also, you should elaborate on the Samples-Per-Pixel part. Makes a big difference in final quality.

    Good tutorials though!
  • Mechadus
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    Thank you very much for taking the time to create these papers and share them with the community. I especially liked your coverage of the Vray methods. Though less accurate, Vray is by far my favorite renderer because of its speed - Nice to know I dont have to give it up for AO :)

    -N
  • Ben Apuna
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    Great color math article, Thanks :)
  • Xoliul
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    Xoliul polycounter lvl 14
    Ott wrote: »
    I like your AO tutorial, I just wish you had images exactly explaining to people how to set some of the stuff up. It took me awhile to get all the steps down so they are easily burned into my brain, but for a noob telling them how to do a lot of your steps can get really confusing.

    Once I started using MR as my AO renderer, I haven't looked back. Used in conjunction with Crazybump's sexy specular via normal map settings, you have some killer AO if you know what you are doing.

    Well i thought about that, but that might go beyond the scope of the article, I´m really supposing one already knows how to RTT. Maybe I´m being a bit lazy, but people should be able to find out on their own where some of these simple settings are; becoming good at anything requires some dedication at the least :)
    But if people really deem it necessary, I can add some more explaining.

    Hey and what is specular via AO in Crazybump ? I never use that program, the Nvidia filter does the same for me.
    Something you suggested did stand out though on Method 3:

    As far as I know, simply assigning the diffuse as AO and then rendering-to-texture a diffuse map negates the need to set self-illumination or make it white. It should be all of that by default and work correctly. Don't forget to turn Shadows on in the render-to-texture. I always forget that :poly142:
    In my case, that renders out a map that is slightly grey where the AO would be white? I'm not sure why this is, but setting self illumination makes sure this doesn't happen. Diffuse or Completemap does not really seem to matter once it's self-illuminating.
    Also, you should elaborate on the Samples-Per-Pixel part. Makes a big difference in final quality.

    Good tutorials though!
    For Vray you mean ? Good point, that is quite advanced stuff however.
  • oXYnary
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    oXYnary polycounter lvl 18
    Somewhat an aside since you focused on Max. I would find it interesting comparing it to a third party AO baking like Xnormal. Especially on speed.

    Good articles!
  • Ott
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    Ott polycounter lvl 13
    Xoliul wrote: »
    Hey and what is specular via AO in Crazybump ? I never use that program, the Nvidia filter does the same for me.

    The image below is a quick example of using Crazybump to do a quick pass over your normal map to generate an additional bit of detail to your AO. I've never really gotten CB's "Occlusion" to look nearly as good as Specularity, so I will occasionally use the Specularity and adjust a few values to get a really strong fakey AO from the normals.

    planetest.jpg

    Once I have the map I can adjust intensity and levels and whatnot in Photoshop to get a good AO overlay to work in conjunction with my Render-to-texture AO bake.

    Couldn't I get the same amount of detail from using Render to texture from the high poly source?

    Maybe. It really depends on the specific object, amount of overlapped UVs, how much time I have and whether I am doing a true high poly version or a simple detail overlay version. When using this in conjunction with a detail overlay in the normals and you don't have any actual high poly source, Crazybump works great for generating an additional AO.

    It also works great since it is so fast and you can dump it in and get a quick idea of whether its even worth using or not. It sometimes requires a little cleanup, but definitely a good tool to play around with.
  • Xoliul
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    Xoliul polycounter lvl 14
    Though I'd kick this one back up for some new additions:

    http://www.laurenscorijn.com/articles

    I wrote/recorded a few for CG tuts+, one about architectural rendering, another one about car rigging, plus there's also the viewportshader setup article. Another video about shader setup is coming soon. I have a lot more planned also!
  • NautalusX
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    Yea, I'd be intrested in a Vray Irradiance Map vs XNormal AO bake comparison article. Please:)
  • Xoliul
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    Xoliul polycounter lvl 14
    The Importance Of Reference

    Wrote a new one together with Dukesy!
  • Eric Chadwick
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    Hey Laurens, if you'd like to put something in the wiki, send a PM to Vito and he'll set you up with an account.

    Great articles!
  • Xoliul
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    Xoliul polycounter lvl 14
    Yeah I PM'ed him already (back in may even), never got anything back... ? I guess I should try again?
  • CrazyButcher
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    CrazyButcher polycounter lvl 18
    same here, tried to get an account for that wiki for years...
  • Eric Chadwick
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    Well that sucks don't it? Hmm
  • Michael Knubben
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    Same here, no response.

    Such a cocksmith
  • Ruz
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    Ruz polycount lvl 666
    BTW you don;t have to move overlapping uv chunks 1 unit to the right, you can change change the 'w' value in the uvw to 1 or a higher nuimber than the other chink it s overlapping.
  • Eric Chadwick
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    ahmed,

    Please do not reply to an old thread, unless you have some new information that is relevant to the thread. This is a five-year old thread, and your post does not add useful information. This is seen by all those who open the thread, as a waste of their time.

    An example of a useful reply would be something like a link to a related technical article. For example...

    Some of Xoliul's articles are now on the wiki, here
    http://wiki.polycount.net/AmbientOcclusionMap
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