1. #1
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    Post Lighting Tutorial

    Lighting Setup Tutorial:

    (45 seconds @ 28.8 Kbps)



    Step 1: Default settings, ZMode: OFF
    (EDIT: ZMode:OFF is very fast, but does not allow for the creation of 'accurate' shadows. It is fine for certain illustrations where a sense of depth is desired, but not for 3D scenes where accurate shadows are desired.)

    Step 2: ZMode: ON, Length: 50 is not enough...
    (EDIT: Shadow Length determines 'the maximum length of the shadow,' according to the pop-up help in ZBrush. It would be more accurate to say that it determines maximum distance beyond a pixol at which a shadow will be generated. If a pixol should cast a shadow on a second pixol, but the second pixol is at a distance from the first pixol that is greater than the Shadow Length setting, no shadow will be cast.)

    Step 3: Length: 150 - Some render artifacts are present.
    EDIT: It has been revealed by Aurick that when Rays is set to the default of 1, and certain wierd render artifacts show up in the shadow of a complex model, this is due to one ray being insufficient for ZBrush to calculate an accurate shadow. The Rays setting needs to be increased. /EDIT

    Step 4: Rays: 2, Length: 200. Increased the Rays and Length. Setting Rays to 2 results in some rendering artifacts common to Global Illumination renderers when the number of Rays are small. Increase the Rays for less spottiness or graininess on the surfaces near shadows. ZBrush's renderer will slow down as the Rays are increased, but it is still lightning fast compared to the hours some other rendering engines need to do the same number of rays.

    Step 5: Rays: 25 - Increasing the rays causes the shadow to soften, while reducing the spottiness. Often the very soft shadows are desirable, but decreasing the Aperature will create a strong shadow once again.

    Step 6: Aperature: 15 - stronger shadows, but still very soft.

    Step 7: Aperature: 2 - strongly defined shadow, with a touch of blurring of the shadow outline as distance is increased.

    Step 8: Rays: 50, Length: 500, Shadow Intensity: 100, Light Intensity: 1.0, Ambient: 0 - These are more ideal settings for a strong, accurate shadow in this situation. Increasing the rays does not greatly improve the render in this situation, but it will greatly increase render time if it is maxed out. In some scenes or light set-ups, a higher number of rays may be necessary to acheive similar results. The Shadow Aperature may need to be reduced in other situations, and certainly in the case that softer shadows are desired.

    EDIT: Increasing the Length in Step 8 was to make sure that some render artifacts in the shadow were minimized. The Shadow Length refers to the distance a ray travels beyond the shadow-casting pixol to see if it hits a surface. If the distance to a surface behind a pixol is greater than the setting for Shadow Length, then the pixol will not cast a shadow. Therefore, in Step 2, the lower sphere casts a partial shadow, and the upper spheres do not cast a shadow at all on the ground plane. However, the upper spheres do cast shadows on the sphere below. The pixols in the middle of the bottom sphere were too far away from the surface behind it. Only the pixols at the lower edges of the bottom sphere were close enough to the ground plane for a shadow to be cast when the Shadow Length was set to 50. It also 'seems' that even at high settings, the center of each sphere's shadow is slightly lighter than the edges. So I increased Shadow Length to the max to minimize this effect, IF the effect is due to Shadow Length. I'm not certain of this.

    To see the effect of Shadow Length, draw a shphere on a plane, turn on ZMode, and Shadow in the Render palette. Gradually increase Shadow Length and observe the shadow as it lengthens and fills in. Try a tall, thin cylinder if it is not clear to you what is happening./EDIT

    This should give everyone unfamiliar with the Shadow palette a good understanding of what these settings will do, and a good base from which to begin to obtain the ideal shadow in your scenes.
    Jay

    "Talent and all that for the most part is nothing but hogwash. Any schoolboy with a little aptitude might very well draw better than I perhaps; but what he most often lacks is the tough yearning for realization, the teeth-grinding obstinacy and saying: even though I know I'm not capable of it, I'm still going to do it." -- M.C. Escher, in a letter to his son Arthur, 12 February 1955

    http://www.ejectejecteject.com/

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    Thanks for putting this together. It's a handy visual reference for understanding the basis of shadows in ZB and something that can be added to along the way. There are so many options under materials and lighting that all interact it can be hard to gain an intuitive understanding of how to achieve a particular look in the render.

    I'm still trying to get my head around shadow length though and understand exactly what it does. The range of values in 1.51 is different from 1.23 and the manual doesn't really explain how they are derived. I would have thought that the length would be derived from the angle of the light wave in relation to the object, but this angle can be changed by altering the position of the lights, so maybe length means something else.

    [Edit] In the manual it talks about objects having infinite depth so I am guessing that shadow length effectively revolves the light around the object (in your images seemingly parallel to the ground plane). Looking at your pictures though there is a big difference between 50 and 150 but very little between 150 and 500 so if this is right I am intrigued to know how ZB works this out, i.e. how it 'revolves' the light (what arc it takes) and what its limits are. I am wondering if light position and type affects this - were you using ZB's default light setup? If not could you tell us what you used?

    It becomes curiouser and curiouser and any explanation for the confused is appreciated

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    Hey thanks for this. I have been wondering what the differences were in these settings. Now if there was just a way to get both shadows and transparency on the same object I would be a happy camper!!


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    nice tutorial , this way people can save some time. No longer endless test renders to check if the shadow is correct

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    Bonecradle,

    Length basically has to do with shadow length. What that means is that if you use a short shadow length, the shadow won't be complete for the whole object. For example, let's say for a human figure standing on the ground, if you have a shadow length of about 50 or so, you would only get shadows for the feet and then the shadow would rapidly fade off (Look at figure #2 in the images that Jaycephus posted). If you have the shadow length maxed out at 500 then you would get a shadow for the whole figure. There are times where you might actually want a short shadow length, however.
    The direction of companion mind should cooperate with rescue at lighting of a red lamp,or a buzzer. Please give me connection from a nearly extraordinary telephone.

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    Thanks for the reply WingedOne. Shadow length as a function of the completeness of the shadow, rather than how much it has been 'stretched' - it sounds logical but doesn't quite fix my confusion

    Look at Fig. 1, which has the same shadow length value as Fig. 2 but seems to be casting a complete shadow as long (or longer) than Figs 3-8 but in a different direction (I had assumed the 'aberant' shadow in Fig. 2 was due to zmode being turned on - see also the banding). A good comparison is between Figs 1 and 3 (the only differences are length and zmode).

    I'll have to go away and experiment - that's the joy of it

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    Excellent info-at-a-glance jay!
    Well done too!

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    Thanks, Mike, everyone,

    See the EDIT I made above that gives a little more information about Shadow Length.
    Jay

    "Talent and all that for the most part is nothing but hogwash. Any schoolboy with a little aptitude might very well draw better than I perhaps; but what he most often lacks is the tough yearning for realization, the teeth-grinding obstinacy and saying: even though I know I'm not capable of it, I'm still going to do it." -- M.C. Escher, in a letter to his son Arthur, 12 February 1955

    http://www.ejectejecteject.com/

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    Cool

    Tnx for this explanation Jay!!! Well done bro and tnx for sharing !!!
    Italian Zbrusher

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    Aha, thanks for the answer Jaycephus. That makes things clear.

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    A great reference Jay, many thanks for such an involved posting.
    ......Nobody tries to be lah-di-dah or uppity--There's a cup-o'-tea for all.

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    THANKS JAY
    By Leo
    P.s. i can spend more time all around not in front of monitor to test the results....

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    Very cool info J-don't think I've ever really known just exactly what shadow length was.

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    Thanks to the many who have responded to my little post.

    I edited Step 3 with this little bit of information:

    quote:
    It has been revealed by Aurick that when Shadows:Rays is set to the default of 1, and certain weird render artifacts show up in the shadow of a complex model, this is due to one ray being insufficient for ZBrush to calculate an accurate shadow. The Rays setting needs to be increased.


    If there needs to be a correction to anything I have up there, or there is another bit of information that would be helpful to a newbie, or not-so-newbie, please post it! Thanks,
    Jay

    "Talent and all that for the most part is nothing but hogwash. Any schoolboy with a little aptitude might very well draw better than I perhaps; but what he most often lacks is the tough yearning for realization, the teeth-grinding obstinacy and saying: even though I know I'm not capable of it, I'm still going to do it." -- M.C. Escher, in a letter to his son Arthur, 12 February 1955

    http://www.ejectejecteject.com/

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    Talking

    Thanks for the info, very useful indeed.

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