Cineversity

Is there a way to control the falloff or the focusing of the spot lights in Cinema?

Do you have to use an IES light for this?

Hi Phloptik,

Light sources are a wide field, talking about practical light (... which I love since my first stage work, and have certainly taken advantage from this experience in my DP work).

There are many areas where you can adjust a light source in C4D. But the main fake-control is in the Detail-tab “Contrast”, which “simulates” the size of an light source. As the “Focus” can be understood as the harshness of a light, the smaller the light source, the harder the light on the surface and practically resembles this in the shadows. (In conjunction with distance as large soft-lights—far away—turn practically into point-lights).

Focus might indicate the border of the light; How precise the cone is when it hits an object. Many light sources use lenses for that, which results (sometimes) in a chromatic aberration “CA” (compare PIXAR movies) and the softness of the border is then colorful. The “in focus” is then the Detail> Inner Angle and Outer Angle. The closer these values match each other the more the light will appear to be in focus. With the Gradient you can even fine-tune this, with gray values in terms of brightness and with color for the CA.

Perhaps I took your term “focus” too loosely, and you might specify where you need the effect you are after.

IES are lights based on measured data and not created to adjust them, they are also pretty sensitive to scale. They are great for 1to1 simulations in Architecture Visualization, even with all the short comings with the relation between camera-surface-render(GI).

All the best

Sassi

In maya it is called the Penumbra Angle - The angle (in degrees) from the edge of the spot light’s beam over which the intensity of the spot light falls off linearly to zero.

Are you saying to use the gradient to control this? That’s the only thing I see that may work -

I was using the word fresnal in regard to stage lighting yes, haha - I was looking for a word that was more universally understood - Maybe Penumbra should do the trick -

Hi Phloptik,

The three areas are called “Umbra”, “Penumbra” and “Antumbra”, and are in used since (?) ever, for example to describe in paintings the way a shadow is created.

It is based on a relationship to the size of the light source, the distance, and the objects (casting and receiving).

The Penumbra is the partially created shadow, partially, at least to my understanding, based on the limited used area of the light source itself, e.g., the sun. In other words the constellation between light source and the size of each in relation.

If you like to adjust the shadow in that way on the object itself, use the simulation (fake!—but fast) of the Detail>Contrast. If you like to have these qualities on objects that receive these qualities (and with that as well on the casting and self-shading object as well) you need to use area lights as well as shadows.
BTW: “Soft-Shadow” (C4D-term) is a simulation-method, and based on an exploration of the space, like something along raster-points and there the interpolation of such. If you like a good quality, avoid “Soft-Shadows” (as the name of the shadow option is use in C4D more or less wrongly) all together.

The way the light is calculated on an object is certainly dependent on the Illumination method as well (such as Blinn or Oren-Nayer). It all plays together, and is on the end based on formulas, rather than reality. In GI you might not see the effect of the Illumination settings mentioned, while using only objects (with luminance) and images to illuminate a scene.

The “Gradient” might look partly in that way, but is not the same, if the word Penumbra is used as in science or art.

The Fresnel is a lens that takes advantage of the fact that the change of medium and the angle where it happens is more important. In that way the Fresnel Lens is a lens which is step by step reduced in depth, and roughly creating the same effect as a full lens. In that way it is lighter in weight, stores less heat and is over all easier to handle.

Good luck with set up, sounds like you take care of details :o)

All the best

Sassi

I found a nice little image:

http://en.wikipedia.org/wiki/File:Diagram_of_umbra,_penumbra_&_antumbra.png

Thanks Sassi - I will play around with these techniques and see what I come up with -

This usually comes up when I have spots(in a smaller room) and when the light is cast from the ceiling it seems to make a hard edge when it hits the floor. I’ve tried to solve this a few times but the deadline usually is too tight.

Do you know if any options have changed from R12 to R14? In terms of spot light cone options?

Hi Phloptik,

My typical suggestion is based on the idea to work carefully with the Diffusion channel. If this is ignored the light on the objects will not appear in the quality it could. To set up this channel even sloppily with a mid gray “color” opens up a much simpler adjustment for the scene.
In this way the light can be even above 100% without burning into the texture.

The light has (last time I counted it, way over 100 parameters. To keep track of what has changed from one to the next version is already a challenge to keep that in mind, to jump even two versions… well I can’t answer that, working with R14 since last year. ;o)

In terms of light adjustments—I’m not aware a significant changes (but e.g., Export to AFX checkbox).

Deadlines, I hear that not the first time, we are all used to that and have our basics down, to enjoy even harsh deadlines; Following the many presentations from John LaPore (e.g., Siggraph 2013). But I know what you mean, there is always something else. That is the fun part, isn’t it?

My best wishes for the project

Sassi