Rhino #4: Lighting Set Up

After we have defined our cameras and views, first step for creating convincing images is setting up scene lighting. Here's how to do this in Rhino.

Daylight Set Up

Look At How Nature Works

Before we dive into Rhino’s lighting system, a little theory about what constitutes a daylight and how we can use it.
Basically, a daylight system consist of a sky and sun.

Sky will give us nice soft shadows that help see the shape of our objects.
Skylight comes from all sides equally, and that is why it results in such a finely detailed lighting.

sky

On the other hand, sun light is very sharp, coming from one distant point, and usually doesn’t light up very much, but it provides a good contrast:

2-sun

See how we can get interesting graphic effects by positioning the sun carefully?

Here’s how the two look together, see how using sun shadow gives a very strong “graphical” diagonal. It also adds a dramatic effect to the image because it looks like sculpture is “hiding her eyes” from the sun. So sunlight is very useful for effects like this (or in case we need to do a real shadow study).
But it’s the skylight that actually helps us understand the space by illuminating the parts in the sun’s shadow, too:

2-sunsky

PRO TIP:
Always use sky to illuminate your scene (at least the daytime scenes)
.
Use sun only to give accents by shadows.
In other words, for exterior scenes you should always use sky. And sun – you only use it if you want to emphasise the shadows.

Now let’s see how we actually do this.

Setting Up Sky

Turning on the skylight in Rhino is very easy, just click sun icon on Render Tools to open Sun Panel:

3-sky-on

That’s all!
Important: Do NOT turn on the sun here! Built-in Rhino Sun is too inflexible and basically useless, so we’ll be making sun “manually” later.

Now if you hit render button (first button on Render Tools panel), you’ll get:

sky

Faking The Sun

I just told you not to use sun that comes in the Sun panel. You can give it a try, and it comes useful when you need to see accurate sun shadow on a precise time/date and GPS location. However, since we can’t modify the sun intensity or color, it doesn’t work for the aesthetic purposes we need.

So we will create a Directional Light to simulate the sun.

Directional light is a kind of light that gives the parallel shadows (like sun). The position of direction light doesn’t matter, but it rotation does: the rotation of this light type defines the angle that the shadows will fall.

Here’s how to create and rotate the directional light to control the shadow. Note, in order to see the shadows on screen, choose “Rendered” shading type for our view.

3-light-onNote: If you don’t see the light in your view (so you can’t get to rotate it), this is because lights are turned off.
See Display Panel:

If we render now:

3-sunsky

This is not bad, but looks too clinical, because -apart from “sun” washing out the wall on the right side-  sun and sky are never so grayscale.

 

Adjusting The Sun And Sky Colors

In real life, the color of the sunlight and the skylight changes depending on many factors, most notable the time of the day. Let’s see how light colors typically change during the day:

3-col-morningMorning
Skylight is blue-ish cyan (blue with slightly green hue), and the sunlight is strong and bright yellow-orange-ish (yellow with a slightly red hue) . Generally this results in a relatively cold-looking image (remember the lecture about the color, 1A?)

Afternoon
Afternoon we see both sky and sun move to slightly hotter hues (more red). So sky is now blue purple-ish (very little red) and sun is definitely more orange:

3-col-aft 3-col-eveEvening/Sunset
Here the sky is very intenstely blue-purple, and the sunlight is dimmed (not strong) but intense orange/red hue, which can result in a very purple-ish image:

So that was the theory, now let’s see how we adjust these colors in Rhino.

Adjusting Sun Light Color And Intensity

Here’s how to change the color of any light (not only our “sun”), using Properties Panel > Light:

  1. Select the light you want to modify
  2. Open Properties panel, then
  3. Light Properties (light icon)
  4. Intensity: you often will want to tune down intensity of light between 60-90.
  5. Color: click here to change the light color.
  6. Let’s try to simulate some afternoon sun, so go with a desaturated orange. Note: You always want to use very desaturated colors for lights and sky, otherwise your scene will look too artificial.
3-suncolor

If we render now, we see that the color starts to add life to the image:

3-suncolor

Now we only need to change the sky light to make it more blue.

 

Adjusting Skylight Color

Since in Rhino “skylight” is not a typical light object, we can’t select it and change the color as we would with any other type of light.
Instead we need to change the Environment to affect sky light.

  1. Click Render Settings icon
  2. Find and click Rhino Render on the left panel of the Settings window (Rhino Render should be open by default).
  3. Scroll down until you see Skylight (should be turned on, right?) and then turn on Custom Environment.
  4. Click + NEW to add new environment, from file.
  5. Choose “Blank Environment” to start from scratch (you have also some predefined environments inside that use image instead of color, but let’s start from simple color environment)
3-skyenv

Now we are asked to modify the parameters of the new environment, let’s change name and color:

  1. Change name to “Sky Daylight”
  2. Click to change the color to something blue-ish.
  3. Note that you can access this interface by clicking Edit in Render Settings > Environment.
3-skyenvedit

Now if we render, we see blue hues in the shade, and yellow-orange in the sunlight, which is more realistic for a morning light. We can fine tune these values to get the desired effect to simulate the time of day and atmosphere we want.

3-sunskycolor

With more blue in the sky, and more red in the sunlight, we get a more afternoon feel:

3-sunskycolor-aft

Now let’s see ALL of this in a video (I cut the video at the end because rendering process was a bit slow):

 

Night-time Lighting Set Up

Unfortunately, setting up night-time shots is a bit difficult in built-in Rhino renderer due to it’s limitations. Let’s take a look how a nighttime render would look:

Night Sky

Let’s first try and render the other camera, Pool View, with the same daylight conditions.
See the end of tutorial #1, about Named Views  if you forgot how to show the Pool View:

4-pool-solid

Apart from sunlight angle not really doign this image a justice, we see that the glass objects are as white as anything else. Since we will not get into materials now (and it’s always good to test lighting on a white model first), we’ll just hide the Glass layer and render again:

4-hidegalss

Now it definitely looks more realistic. Then we will turn off the sunlight:

4-off

And now we need to make sky darker.

Multiple Environments: One For Daytime, Other For Night

But what we will do is CREATE ANOTHER ENVIRONMENT first, so we can easily switch between daytime and nighttime sky.

Here’s how:

  1. Duplicate the Sky Daylight and call it Sky Night
  2. Change the color of Sky Night to dark blue
  3. Now in render settings, change the skylight environment to Sky Night. We can always easily switch between the daylight and night sky by having different environments
  4. See in render settings, just above the skylight, you can set the background color for the rendering. Best thing you can always do is to chose the same environment as the sky.

 

Adding Artificial Lights: Rectangular Lights

When it comes to artificial lights, there are no solid rules, and all depends on our design and the effect we want to make. Usually it’s good to simulate artificial lighting by adding large rectangular lights pointing downward, just below the ceiling.

Let’s try, and create a rectangular light in the big room, then rotate it downward and move just below the ceiling.
Take a look at the size, rotation, location as well as the color of the light (which we want to be yellow-ish):

5-rectlight

Here’s how we got this:

 

Please note that, as we seen in video, usually the artificial light in Rhino will be very dim, so we need to do two things:

 

Use Tone Mapping To Improve Image Contrast

See the following options, play around for best results:

  1. Exposure: move around the slider or press the button
  2. Tone Mapping: Reinhard 2001 usually gives good contrast for night time renders.
  3. Set As Doc. Defaults: If you’re happy with results, by saving as defaults you won’t need to adjust this for every new rendering you make.
  4. Apply while rendering: This simply means that this tone mapping will be visible even when Rhino is still rendering, not only when it finishes.
5-tonemap2

 

Adding More Lights

Let’s add another rectangular light just below the ceiling of the pavillion canopy seen in front of our camera view. See the size, location, color and multiplier of this new light:

5-rectl2

Here’s what we have when we render:

5-rect2ren

And unfortunately this is pretty much as far as we can get with Rhino built-in renderer.
You can try to add some spot lights, ideally behind the bench, but Rhino will not calculate them very well, especially because lights don’t have a decay (which is a natural property of light to lose its intensity over distance).

If you want to have more control over lights and better night renderings, you will to use VRay, Brazil, Maxwell or similar rendering package…

If it’s any consolation, if we try to render the other view (the statue) with the lights we have, at least that one will look quite decent (see the Exposure and Tone Mapping options):

5-nite2

Note: To easily access lights, use Lights Panel:

5-lighpanel

Any questions?

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