- [Instructor] The other Distribution Type
we will want to use very commonly
for a Max's Photometric light is Spotlight
which will emit light in a cone shape.
I've got a dramatic theatrical scene set up here
in which I have a Key light
which is going to be a Spotlight.
I've also got a Fill light and a couple of Rim lights.
Those are all currently disabled, they're turned off.
And so their gizmos are displayed as black
in the Viewports.
Let's do an ActiveShade Rendering.
And what we currently have is a default Photometric light
for the Key light.
I'll select that and go to the Modify panel.
And it has default parameters, 1500 candelas.
The Light Shape is Point
and the Distribution is Uniform Spherical.
Let's brighten this up.
We'll increase the number of candelas by a factor of 10.
Increase that up to 15,000 candelas,
and now it's illuminating the surface
of the sculpture pretty well.
Let's switch over to lumens for a moment.
I want to show you some thing.
The lumens equivalent of 15,000 candelas
is about 188,000 lumens or so.
Okay. So remember that, 188,000,
quite a high number.
Now let's change the Distribution Type
in the General Parameters rollout,
set that to Spotlight.
Okay. We didn't see of lot change
in our ActiveShade Render
and in the Viewport
we now see the light icon is cone-shaped,
and we also see a couple of concentric cones
projecting into the scene.
But most interestingly,
if we look at our intensity,
go back over here,
we see that we now have 4,270 lumens.
So it went from 188,000 to 4,200 or so.
Max did this
in order to maintain the same approximate level
of incident light on the surfaces.
So Uniform Spherical Distribution
emits light 360 degrees horizontally
and 180 degrees vertically in all directions
but Spotlight Distribution constrains that illumination
within these Cone angles.
So the overall output is automatically reduced, over here,
in order to maintain the same brightness
over a smaller area.
The candelas' value, if we go back over there,
is still 15,000.
Only the lumens' value readout actually changed.
And that's one of the reasons I prefer
to work in candelas whenever possible.
The numeric entry fields always remain constant
regardless of the Distribution Type
or any other light parameter values,
such as the angles of the cones.
In that Distribution, Spotlight rollout,
we have two important parameters,
Hotspot/Beam,
and Falloff/Field.
Hotspot and Falloff determine the spread
and the softness of the edge.
The Hotspot is indicated in the Viewport
by this inner bright yellow cone.
The illumination will be at full intensity inside that cone.
And it will fade to zero intensity radially
when it reaches this outer cone,
which is the Falloff or Field.
To change the look of the Spotlight,
to constrain it to a narrower angle
and get a sharper edge,
we can adjust these angle values.
Let's bring the Falloff amount down,
click and drag on that spinner
and reduce that and bring that down.
We can see it's changing in our Viewport.
If we bring it down enough
we'll also see the Hotspot angle start to change by itself.
What's happening is that
Max is maintaining a minimum difference
between the Hotspot and the Falloff.
It's a minimum of 2 degrees by default.
If we set the Falloff to 18 degrees
then the Hotspot will automatically change to 16 degrees.
And if I set the Hotspot to 18,
then Falloff will automatically be 20.
We can change that behavior.
We can go to Customize, Preferences.
And in the Rendering tab
we see Hotspot/Falloff Angle Separation.
We can set that to a value of 0,
click Okay.
And now if we want
we can set these two values to be the same.
We can set them both to be 18 degrees
and that gives us a very sharp edge
or a limelight type effect.
With Hotspot and Falloff both set to the same value,
there's no variation in intensity across the field here,
or the area illuminated by the Spotlight.
And for that reason
if we switch our Light Distribution
back over to Uniform Spherical,
we don't see really any change
in the amount of light hitting our subject.
It's just that now
the light is spreading over a larger area.
So Max is set up to try to maintain the overall illumination
regardless of the Distribution Type you choose.
And again, it does that
by changing the overall intensity in lumens.
We go back to lumens, we're back to 188,000.
All right, I'll choose to work in candelas.
Let's set our Distribution Type back to Spotlight.
Okay, the effect I want to achieve here is a soft spot.
I can reduce the Hotspot, make that smaller.
Maybe bring that down to a value of 10 degrees.
Now I've got a nice soft edge here.
But you'll notice that we don't have soft shadows.
The shadow is very hard.
The cone angles over here
do not affect the softness of shadows.
And also the cone angles don't affect the softness
of the actual lighting known as suffusion.
We're getting a soft edge to the light cone
but with the Light Shape set to Point,
we're getting very hard lighting
and that's because all of the light rays are coming
from a single infinitesimally small point in space.
So we can't get soft shadows
and we can't get soft lighting from a Point light source.
The cone angles also don't affect
the decay of intensity over distance.
The 3ds Max Photometric lights always conform
to what's called the inverse square law,
also known as quadratic decay.
The intensity of an ordinary light source
will decay with the inverse square of the distance.
And this is physically accurate for a light source
that does not have a lens or a reflector
or any other way to focus the light.
But a real spotlight instrument or fixture
does have a lens or a reflector to focus the light
into something called a collimated beam.
And that will reduce the rate of decay
and effectively extend the light to a greater distance.
Well, unfortunately the 3ds Max Photometric Light
cannot fully simulate the optics of a real spotlight.
We can make the rate of decay greater
with this Far Attenuation section here,
but we cannot reduce the rate of decay
to make the light go a greater distance
or to simulate a collimated beam.
However, that effect can be achieved with the Arnold Light.
It has a parameter called Lens Radius.
I covered that in my course,
"3ds Max Rendering with Arnold".
The good news is that the 3ds Max Photometric Spotlight
does have a mechanism to achieve suffuse
or soft illumination and soft shadows.
And that's just simply the shape
and dimensions of the light.
For a Spotlight,
the most intuitive choice for the shape would be a Disc.
So let's set the "Emit light from" to Disc.
Now we see a Disc here in our Viewport
and we have a radius.
We can set that to some value.
Let's maybe make it 10 centimeters.
And we see in our ActiveShade Rendering
we are now getting some soft shadows
and we've also got softer illumination
on our subject.
Okay, we can finally turn the other lights back on again.
The ones I've got disabled.
We can select the Fill light,
and in its General Parameters,
turn its Light Properties switch to On.
And likewise with these Rim lights back here
we can turn those on,
turn both of them on
and now we've got our lighting set up.
It's a nice aesthetic rendering
with a traditional 3-point lighting scheme.
That's how to set up 3ds Max Photometric Light
with Spotlight Distribution.