By Mike Embleton

Introduction
This is a quick tutorial to share some quick and easy techniques that have proved useful to me when creating realistic daytime lighting in a scene. Lighting is often neglected or not given as much consideration as other aspects of 3D, such as modeling and texturing, yet lighting is very important!

Many people want to achieve a natural looking daylight look, and yet this can seem hard to achieve. The good news is that it doesn't have to be hard at all! The lighting set-up we will use consists only of two simple elements: a pair of infinite lights, and an array of local lights.

 

Infinite Lights (Element 1)
First, add an infinite light to the scene, and then right away add a second, and glue them together. Now both infinite lights are at the same position and at the same angle, which is important when casting the shadows.

 

Infinite Light 1 Settings

To the left you can see the settings to use for the first infinite light. The Shadow Type should be set to Raytraced, and the color of the light made slightly orange. I would suggest an intensity of about 0.50.

This light will act as our main light source, in this case, the sun. This light provides a distinct and quite hard-edged shadow.

 

Infinite Light 2 Settings

Our second light will add a softer edge around the shadows from the sun.

This time set the Shadow Type to Shadow Mapped, and set Map Size and Quality to High, and Sharpness to Medium. Since these are Shadow Mapped, you will not get transparency effects from this light.

The color of this light needs to be slightly blue, and the intensity should be at least double that of the first light. With both lights now set, we can move up in the hierarchy to have both lights selected.

 

Using the Infinite Lights

Since these lights are glued together, you can rotate them to any angle you want.

Infinite light 1 is used to add an orange tint to the scene and give a crisp, but faint outline to shadows. Light 2 will soften the inside of the shadow where light still bounces inside the dark areas.

To the right is an example of how this light element looks when used with this sample plant pot object.

 

 


Local Light Array (Element 2)

We will now create a circular array of local lights, which will add an overall softness to the shadows in your scene.

First select the Top view from the views menu. Then add a local light to to the scene, and use Normalize Location to make sure the light is at the center of your scene. Next, activate Grid Snap. It is not important what the value for the Grid Snap is (although a value of 1 may be good to start with) as we are using this to obtain the same spacing between lights.

 

Now copy your light at the scene center and move it upward on screen. Copy the center light once more, and move to the right, and repeat until you have four local lights arranged in a cross around the center position of our scene (you can omit the copy in the last step, and just move the light). Grid Snap ensures that the lights all end up in spaced equally and accurately.

Next, glue the 4 lights together as one object, and duplicate this group using the copy button. Use Move Axes to Center of Object, and then use Normalize Rotation, which will set the center for our group. Click on the Axes tool to hide the axes and return to working on the group itself.

 

 

Now right-click the arrow button to bring up the “Object info” menu. You now need to change the Z-axis rotation value to 45 degrees, as seen in the picture on the right. This gives us a set of eight lights, equally spaced, as seen below.

 

  Next, separate the two groups back into separate lights (you can use the Split Hierarchy tool). Then glue all 8 lights together as one group. This will make it much easier to change the settings for the individual lights when working with this array, by making it easier to move around in the hierarchy.

You’ll also want to move the axis to the center of this object again, like we did for the second array of 4 lights, so you can maintain its position when scaling.

You could also add more lights in the array by duplicating this set of eight and rotating again, but I would only recommend this for really big scenes. I do think that eight is the minimum you should have.

 

Settings for the Local Light Array

Apart from the color, which can be different for each light, make sure that all the other settings for the lights stay the same for each light. If you change a setting on one light, you should change it on the others too!

The Shadow Type for your array should be Shadow Maps, with Quality and Map Size set to High, and Sharpness set to medium. For each individual light, I would suggest an intensity of around 0.15, and a setting of Squared for the Light Falloff setting.

I usually colour each lights slightly differently. Starting from slightly orange for one light, and going around the spectrum to slightly blue and back to orange again as I move around the circle of lights. This makes each shadow from each light have a slightly different colour. If they are all set to white, the light from one light will illuminate the soft edge of the light next to it and all but cancel it out.

 

Using the Local Light Array

This array of lights should be placed pretty high in your scene, and from experience, I find that about 3 times higher than your tallest object works out pretty well.

Once you have moved your light array high enough in the scene, scale the array until the circle of lights is as wide as your scene.

To the right you can see an example of how this light array looks, using the same sample object as our test with the infinite lights. For quite a simple set-up, this is a really nice look to the lighting and shadows! You can see how the shadows change color too.

 

Combining Both Lighting Elements

Now it is time to combine both lighting elements that we've created into one scene. You can position the infinite lights to your desired angle, depending on which direction the sun is coming from, and you can of course adjust the colors of both the infinite lights and the light array depending on the time of day.

Our first test is our now-familiar potted plant, and even in a straightforward scene light this, it manages to look pretty good!

When we take exactly the same light setup into a scene that has a bit more happening, then things really come to life! A few extra objects, and we end up with the image below, which gives you a much better idea of how effective this type of light set-up can be.

 

Additional Points

We have already got a good result, and there is nothing complex about our light set-up at all. Things don't have to stop there though!

Depending on your scene, you may want to add other infinite lights to brighten some shadows so they are not totally black. In daylight, it is rare to have a shadow that is genuinely black, and in rendering that can happen in recessed areas like doorways, for example, and that could detract from the look of the final image.

I usually have fill lights pointing from the direction of the camera to the middle of the scene, and another pointing straight upwards. These lights should have no shadows and with a very low intensity, something like 0.1, and they act to simulate how light would bounce into darkened areas, and the light pointing upward simulates how light would reflect up from the ground.

 

Conclusion

When using both these lighting elements in a scene you should obtain quite a soft feel to the lighting and shadows. All lights with shadow maps settings will need to be tweaked to get right. This includes the shadow map sharpness and size, as well as the falloff and intensity.  It depends on the objects in your scene. If you have objects like railings or thin posts, you may find that the array of local lights produces unwanted, fuzzy shadows. In that instance, I tend to just remove the array, and work with the infinite lights by themselves.

If you save all the lights together as one object, you can load it into a new scene so only tweaking is needed, rather than building a new light set-up each time.


This tutorial was originally posted on the Caligari.com's 'Tricks-n-Tips' section.
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