Darker Shadows

woodenauthor

Is there a way to naturally darken a specific shadow in Iray? I'm trying to cast a looming shadow from an unseen menace over a young couple, but the particular shadow I'm looking for is coming out rather light. I considered simply turning down the light source, but I don't want to lose visibility on the couple in question.

Toyen

Render Settings -> Tone Mapping -> Crush Blacks. Give this a try : )

mjc1016

Not really...but there are a couple of ways to go about it.

You can do separate renders...one of everything, except the shadow casting item.  Then in a separate render just the shadow casting item.  Leave the lights the same for both.  Save the shadow render as a png and then layer them in an image editor.

Or you can use Iray canvasses...

SpottedKitty

Every camera in your scene, including the one you're looking through to render, has a default light called a Headlight attached to it. This has the effect of washing out shadows, unless you switch it off. Look at the Parameters tab after selecting your camera in the Scene tab.

Tobor

If the other ideas don't work: Though it takes work to get it right, you can add a "negative" light source that literally sucks the light out of a region. It's best done using a primitive -- a small plane often works. 

After adding the primitive:

1. Apply the Iray Uber shader.

2. Apply the Emissive light shader.

3. Select the plane, and in the surfaces tab, set the color temperature to 0. (This is not essential, but it makes controlling the light a little easier.)

4. Set the luminosity units to ^cm2, which allows for smaller changes in light values.

5. Set the luminosity, dial to a value *under* 0; for example -10. If needed, lift the parameter limits of the dial so you can go under 0. See the docs or other posts in the forum for how to do this.

Getting this to look right will need experimentation in placement of the emissive and its emitter values. However, it's a (old) trick can help in deepening shadows and creating a deeper tone, without affecting other parts of the image. Poser, Bryce, and many other 3D render programs support the same idea.

All this said, Photoshop, layer adjustments and layer mask, and some hand-painting could probably do the same thing. Postwork would probably be my first go-to method.