Change color to shadows
Hi!
I usually use shadow catchers in my rendering and HDRI lighting. A plane... a cylinder... and with Iray matte on, I have my beautiful shadow.
But shadow is always black.
What I have to do to change colour to my shadow (always using hdri and shadow catchyer)? Change in a... I don't know... the color of a shadow projected on human skin, for example.
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Hey,
Well in iRay since it's supposed to work as natural light does to get a shadow that has color in it you need two things:
1. Something to cast the shadow
2. A surface that is highly shiny and reflective to reflect that color light into the shadow
http://www.daz3d.com/galleryimage/image/253351/its-raining-men_full.jpg
If you view the full size of the inlined image then you will see the singing lady and the man taking a knee of the street's shadows both have red reflected from the car into the shadows.
You can increase that effect by increasing the light the car reflects.
Also, I think, if for example you were to make the lady's dress highly shiny, like singers often wear, then light would be reflected from the dress into the shadow and from the car to the dress to the shadow and I think that would turn part of the light in the shadow to purple, if the lady's dress was shiny blue. However, I'm not 100% how much light and reflectiveness the dress would need to achieve that effect.
I am using Sun & Sky, with HRDI you could do that too. I don't know what a shadow catcher is unless by that you mean the surface(s) the shadow(s) are cast on.
Mmmhm... I don't think to have understood well...
In your example you have already a good surface (the street), but I have to make one from 0.
For istance:
- I Have the pic 0. I want to lay... mmhm...a bullet on her belly.
- In the pic 1 you can see how I lay a plane under the bullet, Add the "Create advanced Iray Node Properties" command to add the "Iray Matte" command and render all.
- I join the ending render with original picture with photoshop and the result is pic 2. All shadows on the belly of the lady are... brown? What colour is it? Anyway... How you can see the bullet's shadow is black (except its reflection).
- I understand I have to change the surface of the plane, so - as you can see in pic 3 - I set its diffuse color and specular color... the shadow should be a little bit more brown, but it is always black. You can see well in pic 4.
I don't understand how I have to change the surface of the plan to reach my goal. Where is my error?
Oh, yes... I can fit this thing with photoshop, but I would like have a good shadow in DAZ 3d studio.
P.S. About this... Exists one way to render different layers in different file? It would be good to have one file for the object and one for the shadow
Make that plane a better match to the surface before you make it Matte.
Similar skin colour and reflectivity, and even a slight curve, these will all help to modify the shadow and transfer skin colour onto the bullet.
Thanks, Prixat, but this was just for example... I usually use better meshes for my shadow catcher, but even in those cases, the problem is still there.
My problem is the surface material, not the shape... I change colour and sometimes reflectivity, but... it isn't enought.
So: What I should do to make that plane similar to the skin (or others material)?
You could try exagerating the colour. In that example I might try a brighter orange colour for the plane.
Is your lighting also matching the image lighting?
You don't understand the pricipal of what my render illustrated. You must have reflective surface(s) or a light as a secondary source of light begin cast into the shadow but not a strong enough source of light to overwhelm the creation of that shadow. Since you want color that that light source, whether it is reflected or original, must be in the color you want cast into the shadow(s). A bullet and belly are irrelevant to that. It's only the shadows and the light sources that matter.
I believe in the "fix it in post" theory. Accept whatever color you get. In Photoshop, make a mask for the shadow, then fill that mask with anything you like. Argyle if you got it.
This could be done in two minutes. Who knows how long it might take to get the effect you want solely in Iray.
In any case, coloring shadows typically involves complementary color math. This is why the impressionists chose purple for shadows in sunlit (yellow) snow. To change the color of a shadow, you must provide a colored light. The complement of white light is black; that's why you get black shadows. Perhaps I missed it, but your posts don't mention what color of light you are using.
A picture (and movie) is worth 10,000 words. This common science experiment shows how you get color complement shadows from different colored lights:Take note: none of the three shadows are colors of the light sources. The shadow colors are the subtractive complements of the additive color sources.
https://www.exploratorium.edu/snacks/colored-shadows
Wow, pretty neat. Especially the picture of the rainbox shadows around those hands.
There are two important points to remember:
1. Iray attempts to emulate real-world lighting, and
2. Shadows aren't "things".
What I mean by the last is that shadows are not physical. They are an area on some surface over which light is being blocked, in whole or in part, by some object. In the real world you cannot change the colour of a shadow, since colour is a property of light, and shadows are, at least to some degree, merely an absence of light. Only the light can have colours. A render engine like 3Delight can change the colour of shadows and many other things that are not possible in the real world, because it is not bound by the rules of the real world. But Iray is - that is the whole point of having such a render engine - real world lighting.
If your shadows are appearing black (actually it is the surface of the object upon which the shadow is falling which appears black - real world, remember), then that indicates that the object casting the shadow is completely, or nearly completely, blocking all the light. Normally (real world again), areas in shadows do not appear completely black, since there is usually at least some ambient or indirect light that provides at least some illumination, even in shadow. And that's the key. You need to have one or more things in your scene as well as your subject (just as you would in the real world) that can bounce some indirect light around (reflected and refracted light) to give your shadowed areas some colour. That colour will be, of course, the colour that the object actually reflects normally under full light, just at a lower level. Just like in the real world. At dusk, everything begins to lose its colour, or so it seems, as the light diminishes. So think light, not surfaces.
thank you so much to all, for all the advices