Having looked previously at the basic environmental lighting set up with HDRi sky domes we are now going to look at some of the internal lighting set up.
Our general approach to all aspects of 3d visualisation is to attempt to recreate natural conditions as closely as possible and internal lighting is no exception i.e light sources are set up as they would be in reality from lamps, spots, pendants etc rather than faking the lighting with fill lights and invisible sources. That said it is never a good idea to be too slavish with this general philosophy if it is reducing the quality of the image. After all, photographers often set up specific lighting to create certain atmospheric effects in their images which may belie the reality of a space.
In this scene we have used Vray plane lights, sphere lights and ies lights sometimes alone and sometimes in combination to create specific effects.
The general plane light set up is pretty simple. In this case we used Luminous power for the intensity units but we tend to use Radiant Power more these days which is measured in Watts. It makes no difference to the light output but can make a big difference to the unit values making it slightly easier to manage e.g 350000 lm = 500 w (approx).
It's usually easier to use temperature for general internal lighting rather than colour unless you are aiming for some specific coloured lighting effects. The internal lighting in this scene ranges from 3000 kelvin to 4500. It's always worth adding a bit of variation to internal light temperature depending on the type of light source. A kitchen pendant light is likely to be significantly warmer than a fluorescent strip light under the cupboards. The plane lights are generally only made visible if a lens effect is required produced from the intensity of the source, see below. Subdivs are left at the default 32. Shadow bias and Cutoff are also left at the default values in this case. Sometimes these values can be very important to speed up render times if there are hundreds of lights in a scene and many of them, particularly in the distance, need only affect their immediate surroundings rather then the entire scene.
Lens effects were introduced in VRay 3.0 and we tend to use them in most of our scenes. A lot of people still prefer to add lens effects in post but in our quest to reduce post to minimum this provides a really simple and effective alternative. The Vray lens effects control glare bloom and diffraction of light sources. The general rule of thumb is that the greater the intensity of light source the greater the lens effect as in reality.
Bloom and glare work independently although I often use glare alone as bloom can soften an image too much. Depending on the intensity of your light source you may need to play around with the Weight and Size sliders. I generally find that glare works best with these two parameters set at a fairly similar value or if anything the size slightly greater than the weight. Increasing the weight above the size can result in a slightly strange cut off effect but each light source requires tweaking differently.
Bloom is controlled with weight, size and shape but in my experience needs to be used with great subtlety as the glare effects, if used correctly, can do much of the work which the bloom is doing.
Diffraction in Vray lens effects can produce some nice chromatic aberration effects but can easily be turned off interactively without the need to re-render. All these examples are of course exaggerated for clarity.
The lighting of the tree in the court yard was created using a combination of a sphere light and an ies spotlight. The sphere light is used to create a general glow around the light source and the is spot is used to create a more directional flood light up the tree.
Make sure if using two light sources in conjunction like this that they are not intersecting. The sphere light is set to visible so as to create the lens effects therefore the ies (which has an invisible source) must be positioned just in front of the sphere so as not to be obscured by the sphere.
lens effects not only work for internal lighting of course and sometimes they can really add a nice finishing touch to an HDRI. Below is an example of HDRI 1853 shining straight into the camera through the trees with glare set to fairly low values.
In the next tutorial we will have a look at how VrayEnvironmentFog is used in the scene to create depth and atmosphere.