Wouter_standard_studio_lightingmodified3.indd

Standard Studio Lighting

1. Build a test scene lighting tutorial

Start up max and set V-Ray as the renderer.

Go to ‘customize - units setup’ and set both the display
unit scale and system unit scale to metric: millimeters.

Create 3 geospheres with radius 35mm and position
them like I did.

2. The ground plane

We will try to

build an inﬁnite
background in

a simple way.

Usually pho-
tographers use

a big white or
black cloth be-

hind their scene,

curved at the
bottom, so that

you will not see
a sharp edge be-

tween back wall

and ﬂoor.

There are of
course lots of

ways to do this.
I will start from
a cylinder, bend

it locally and
round it off with

a MeshSmooth
modiﬁer. This
way, your

ground plane

is very smooth
and round in

all directions,

making sure you
will not have

disturbing re-
ﬂections from it

(like you would

when using a
box for ex-

ample as ground
plane).

Click the image
on the right to

see all settings
of the cylin-

der, bend and
MeshSmooth
modiﬁer.

Standard Studio Lighting

We need three
materials: almost
white, chrome and

red reﬂective.

Click on the image
to see what set-
tings I used for the

chrome and red
material (this should

look familiar if you
completed the V-Ray

basic materials tuto-
rial).

Assign the materi-

als to the spheres.
The ground plane

also uses the almost

white material.

4. Create materials

5. Test render settings

Open the render settings dialog and do the following:
- set V-Ray as the renderer if you haven’t done so
- output size to 480x360px

- global switches: turn off default lights

- image sampler to adaptive QMC

- antialiasing ﬁlter “mitchell-netravali”
- indirect illumination ON
- Secondary bounces multiplier to 0.8

- Irradiance map settings:

- “low” preset
- HSph subdivs = 20
- environment:
- skylight pure white color, 1.0 multiplier

- reﬂection/refraction pure black, 1.0 multiplier

- system:
- render region division 50x50px
- frame stamp: delete all except render time part.

Render the scene, it should look similar to my image.

Standard Studio Lighting

Instead of the skylight, we will use big rect-
angular V-ray lights to light the scene. They
will also be useful for creating nice reﬂec-

tions (like we did in page 2 of the material
settings tutorial).

Create two V-ray lights and position them
more or less like I did.

The left light is 400x350 mm with a

3.5 multiplier and the one on the right
360x500mm with 5.5 multiplier.

Then go to the V-Ray environment rollout

and change the skylight multiplier to 0.1.

6. Reﬂection planes / lights

7. Render what we have for now

I made the right light brighter on purpose,

that way you create shadows falling in one

direction. If you would set them at equal
strengths, the image will be uninteresting
as lighting will be a bit ﬂat, coming in equal

strength from all directions. The bigger

the difference between the two lights, the

more dramatic lighting will be.

The ﬁrst pic shows left=3.5 and right=5.5

The second one has left=2 and right=7

We will continue with the 2/7 settings.

Standard Studio Lighting

8. Noise!

You’re probably wondering why
the images are so noisy and take
pretty long to render. This is

because V-Ray area lights produce
raytraced area shadows, and these

are very processor intensive. The
noise is coming from the low sub-

div value in the lights properties.

Because we are using adaptive
QMC AA, it is necessary to use

high subdivs values for the area
lights to get rid of the noise. Try

30 subdivs for both lights and ren-

der again. You can see the result
in image 1 (click to enlarge).

Now go to the anti aliasing set-

tings and change to adaptive

subdivision AA with min/max=0/2.
With this anti aliasing sampler, you

can use lower subdivs than with
adaptive QMC to have a similar

noise quality. So change the lights

subdivs both to 10 and render
again. This is image 2 (click to

enlarge).

Standard Studio Lighting

10. Reduce the noise

We will now try to reduce the noise for
both image samplers to see which one is
the fastest for high quality images.

Set image sampler to adaptive subdivision

AA, min/max=0/2
Adjust subdivs for both lights to 30 and
render.

The image is noise free. If you zoom
in a lot, you can see a tiny bit of the

blotchiness.

Now change to adaptive QMC AA, min/
max=1/4
Adjust lights subdivs to 36.
In the QMC sampler rollout, change the

noise threshold to 0.002. The adaptive
QMC AA is very sensitive to the QMC

sampler settings. The noise threshold is

the most important one. (QMC sampler
controls the quality of all ‘quasi monte

carlo’ related calculations. In short, all
subdivs settings are qmc related, except for

lightcache subdivs)

If you zoom in here, you can also see a bit
of noise, but sharper and smoother than

the blotchiness of adapt subdiv AA.

But in this case, adaptive subdiv AA wins

from adapt QMC AA. When you will
add more complex materials like glossy

ones, and more area lights, ﬁne textures,
displacement maps etc, render times for

adaptive QMC will not rise as fast as ren-
der times with adaptive subdiv AA. Usually
when you have lots of glossy effects (also

DOF, motion blur...) it is better to use
adaptive QMC AA..

Standard Studio Lighting

11. Store with irradiance map

Like I said, the reason for the
noise are the raytraced area

shadows. Especially for test
rendering, we can easily disable
them.

The light coming from a V-Ray

light (or also from standard
Max lights) is called ‘direct’

light. This means it is not
GI light (ﬁrst or secondary
bounce). Once this direct light

hits a surface, it bounces back
a bit (depending on how dark

and reﬂective that surface is).
That bounce is called the ‘ﬁrst’

bounce, and it is calculated by
the irradiance map (because we

have set ﬁrst bounce GI engine
to irradiance map).

But the V-Ray light has an
option ‘store with irradiance

map’. This option actually
means ‘treat direct light as ﬁrst

bounce GI light’. Instead of

casting direct light, the V-Ray
light will now cast ﬁrst bounce

GI light and thus it will be cal-
culated by the irradiance map.

This also means that when it

hits a surface, and bounces
back, it will become secondary

GI light, and it will be calculated
by the secondary GI engine,

QMC GI in this case.

So by setting the V-Ray light to

‘store with IR map’, the result
will be that there is no direct

light anymore, only GI light.
This means that all shadows

will also be created by the GI

light. The consequence of this
is, that shadow quality doesn’t

depend on the V-Ray light

subdivs anymore, but the it is
controlled by the GI settings,

namely the irradiance map (and
QMC GI for secondary bounc-
es). This is important, the V-Ray

light subdivs do absolutely
nothing if ‘store with IR map’ is

checked!

(Note that this option only
works if IR map is set as ﬁrst
bounce GI engine. If you have

for example QMC GI for ﬁrst
and second bounce, and lights

with the ‘store with IR map’
turned on, these lights will not

cast any light!)

To illustrate the store with IR
map option, I rendered two

images with the ‘show GI only’

option (global switches rollout).
This option renders the image

only with the GI light, so with-
out any direct light that may be

present in the scene.

The ﬁrst one is with normal
V-Ray light (without ‘store with

IR map’ option).
The second one with the ‘store

with IR map’ option turned on.

You clearly see that in the ﬁrst

example, with the direct light
extracted, there is not that

much GI light to be calculated.
And in the second example, all
light is GI light.

This step is very important, you

should really understand the
difference between ‘store with

IR map’ turned off or on, and

the difference between direct/
ﬁrst bounce and secondary

bounces.

Standard Studio Lighting

12. Store with irradiance map option (2)

The disadvantage of this option is that

there will be more ﬁrst bounce GI light,
but worse, also more secondary bounced

GI light (calculating detailed GI light,
especially second bounce, is very proces-
sor intensive). This means you have to rely

on IR map and QMC GI calculations for
the creation of nice shadows. In product

renders this is not such a big problem,
because there will not be much second-
ary bounces anyway. Light that hits the top

of the spheres for example (ﬁrst bounce),
will bounce back (second bounce) right
into the sky. So this second bounce will

have no effect on the rendering. Only a bit
will bounce in between ﬂoor and objects,

or from one object to the other. But the
secondary bounces will not have such a big

inﬂuence on lighting and shadow creation.

This will become more of a problem in

interior scene lighting. There, the second
bounce will not go to the sky, but it will

probably hit a ceiling or wall, bouncing

again and again... So in these scenes, the

secondary bounces do have a great im-

pact on ﬁnal lighting look and shadows.
So in this case, it would be a good idea to

reduce the amount of GI light, by replacing

the ﬁrst bounce by direct light (‘store with
IR map’ turned off). Think about it, instead

of relying on ﬁrst bounce GI light to start
with, you now start with direct light which

will illuminate a lot of the scene already
(quality is perfect, it is direct light), then
there is ﬁrst bounce (IR map) and then

second bounce. I will show this in the inte-
rior lighting tutorial.

To summarize, for product renders you
can greatly beneﬁt from the store with IR

map option, as there are not much second-

ary light bounces. You will need to improve

the IR map settings, resulting in longer GI
calculation, but the actual rendering of the

image will be a lot faster, as there are no
difﬁcult area shadows to render anymore.
The total render time (GI calculation +

raytracing the image) will be a lot lower
than when you use true raytraced area

shadows (here GI calculation will go faster,
but actual raytracing will take a lot longer,
so combined total result is much longer).

See top image with following settings:
- adaptive QMC AA 1/4

- noise threshold=0.002 in QMC sampler
rollout

- IR map: see settings below top image
As you can see, render times are cut in

half, and compared to the raytraced area

shadows examples, there is absolutely no

noise at all! But shadows are a bit less

precise.

Go to the IR map settings and change the

min/max to -4/-3 and the HSph subdivs to

20. In the QMC sampler rollout set noise

threshold to 0.005 again. These are very
fast test render values. Render the image

again. Notice how less detailed the shad-

ows are now (bottom image, spheres look
like they ﬂoat a bit). But hey, 11.3 seconds

is not bad for a fully antialiased image :-)