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Thread: Top left lighting... like this?

  1. #1
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    Top left lighting... like this?

    When slopping down a somewhat uniform layer of uniformly-coloured paint, a quadrant of the light sphere(?) is clearly visible. Is this how it is supposed to be?

    Canvas
    Grain: default
    Roughness: 0%
    Scale: 0%
    Opacity: 100%
    Metal: 100%
    Color: Black

    Tool(s)
    Paint roller, white paint.

    Thanks,
    Gita
    Attached Images Attached Images  

  2. #2
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    This is a bit tricky to explain...
    Reflective surfaces (silver, for example) use an 'environment map'. That is, a image map of what is reflected by the silvered surface.
    What you're seeing is part of the reflection.
    We made the map have more light in the top left, because that matches where most of the light in the non-reflective lighting model comes from.

    If it were an actual reflection, your face would be staring back at you

    The map is actually much larger than the small amount you see there - if you do a large blob of silver paint tube (making it as spherical as possible...) you can get a better idea of the more deatil in the map.
    But more detail in the flat reflection would interfere with the image.

    So the short answer is... Yes, it's supposed to look like that. One of the things a 'pro' version of ArtRage could possibly get is a way to change the reflection maps.
    AndyRage's mantra for graphics engine code:
    "Sure - how hard can it be?"

  3. #3
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    I think I mentioned somewhere I've been up for a while? Ya, that's it.. *blush* After I'd posted my message it occurred to me that with such a highly reflective surface, and the light where it is, that is what I should expect. Oops. Aye, I know what env maps are, and your explanation was wonderful. Thanks for the clarification, and your patience with us babbling insomniacs (notice how I spread the blame?). =]

    - Gita

  4. #4
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    Heh. It's fine - ArtRage has some very complex technology hidden behind the UI. In many cases we've had to make decisions about How Something Shall Be, knowing that we can't expose a gazillion settings.
    So we've tried to make decisions that will give the best effect and be the most useful to the most people - how they'd typically want it anyway.

    It's definitely reasonable to ask how we arrived at those decisions, or why something is one way, and not another way.
    And I enjoy explaining it - graphics is my passion. Mind you, if I suddenly start spewing terms like Gaussian Pyramid, Second Order bump differentials, High dynamic range lighting with blowout, Microfacets, bicubic interpolation on stretched lattice noises....
    A simple exorcism should restore normalcy.
    AndyRage's mantra for graphics engine code:
    "Sure - how hard can it be?"

  5. #5
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    One I certainly won't be performing. Your easily understood explanation of such concepts (I can't tell you the befuddlement I've seen just around something like HDRI) is exactly what a lot of people (cg neophytes hooked by the low price of admission into cg-as-hobby with no background or understanding of the traditional artistic and scientific concepts underlying it all, *cough* like me) want/need. So if you ever snare some of that elusive "spare time" and want to start a personal blog posting hi-and-low-level-cg-concept stuff for the layperson, imbued with your simplicity and sense of humour... well, you'll have at least one reader/subscriber. =]

    - Gita

  6. #6
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    Thanks for that, JustG. It does wonders for my ego - I'll never get this tee-shirt over my head again
    AndyRage's mantra for graphics engine code:
    "Sure - how hard can it be?"

  7. #7
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    top left lighting?

    So that's cool and all, but how the heck do you TURN OFF the washed out upper left corner effect?

    I'd like to be able to paint such that if I choose blue I get the same blue from left to right.

    I tried setting roughness to 100% on the theory that maybe I wouldn't get any reflection, but I can't seem to find the paper settings that "just" let me paint.

    I tried paper, canvas, etc, and all have pretty dramatic effects. I see pictures in the gallery where people are getting beautiful results, but I'm stymied by the paper settings!

    Also, the canvas grain and so on are all really pretty, but the grain is just about black; it's overwhelming.

    Is there a tutorial somewhere that shows how the paper works? I've read the manual, but it doesn't tell you anything you can get intuitively from the UI.

  8. #8
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    When you're editing paper settings, turn 'metalic' down to 0%. That will reduce the effect of the lighting to the minimum. Keep roughness somewhere middling.
    AndyRage's mantra for graphics engine code:
    "Sure - how hard can it be?"

  9. #9
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    I meant to say "the interface is intuitive, and the manual doesn't say anything that is not already obvious in the interface."

    Anyway, I set the settings as you said, and used Basic Paper.

    I chose the airbrush, and set the color to white, and then covered the whole page.

    I would expect that with smooth paper, and an airbrush shooting for example, acrylic paint, I would get a white result, and I would expect it to be uniform all the way across.

    Instead, as I imagine you can see from the attached .ptg file, I am getting a 25%? gray in the upper left, and nearly black in the lower right. (Edit: I wanted to upload a ptg, but the bbs will only allow jpg)

    Metalic is set to 0%, roughness to 50% scale to 50%.

    I honestly seem to recall that before I installed the updater, I could actually paint with the colors I selected.

    I am finding it physically impossible to get any white color on the right half of the canvas, except by using the eraser. Any other color I choose fades to about 85% black on the right side of the painting.

    Honestly, with the latest version of ArtRage I am unable to actually paint anything due to being unable to paint in the colors I choose due to this extreme lighting effect.

    I am wondering if there is something possibly wrong with the installation?
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  10. #10
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    Ah, is it possible you're painting with metalic paint?
    As well as supporting metalic paper (editable from the paper settings panel) ArtRage also supports metalic paints.
    Take a look at the colour-picker in the bottom right of the window. At the very bottom of it is a small check-box labelled 'metalic'. Make sure that is turned off to use non-metalic paint.

    If all else fails... you need to delete your ArtRage.prs file. On Windows you can find this in "Documents and Settings/(your name)/Application Data/Ambient Design/ArtRage 2"
    Make sure you exit ArtRage before you delete this file. This will reset ArtRage to all its default settings next time you start it up.
    AndyRage's mantra for graphics engine code:
    "Sure - how hard can it be?"

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