Join Brian Bradley for an in-depth discussion in this video V-Ray light types: Rectangle, part of SketchUp: Rendering with V-Ray 3.
- [Instructor] When rendering with V-Ray in SketchUp, there is a pretty good chance that we will at some point need to create artificial or man-made light sources in our scenes. To help with this, V-Ray actually provides seven different light types that can be used to cover pretty much any artificial lighting situation that we may run into. Creating any one of these is, as already noted, a pretty straightforward process that we will see in action over the next few videos. To keep things focused, we are once again going to be working with an artificially darkened scene, although it does need to be noted here that the level of illumination that we will see in our test renders does come in part from the exposure settings on our camera which have been modified to give us a reasonable illumination level right from the get-go.
We are also working here with no GI systems enabled. The first icon on the Lights toolbar then, the rectangle light, is a particularly versatile and powerful lighting option in V-Ray that has been designed to mimic real-world light objects. For this reason, it is probably the light type that we will find ourselves working with most in V-Ray. To make an examination of it, we will of course need to add one to the scene, and so let's come to the Lights toolbar and click to select the rectangle option. Now unlike most of the other light types, the rectangle light isn't created with just a single mouse click.
In this instance, we need to left-click once to set a start point for a light and then essentially draw out the rectangular area that will determine both the shape and size of the light object, with a second left click, locking the light dimensions into place for us. We will, in this instance, want to go ahead and grab the move tool now so that we can raise the light up toward the overhead light housing. We could take a test render at this point in order to evaluate both the illumination and light emission patterns that we are getting from our rectangle light, although if we did, we would quickly see that we currently have a bit of a problem, because, by default, we only get light emitted from just one side of the rectangular light object, which, at this moment in time, is the side that is facing upwards.
An easy fix for this would be to open up the asset editor, and in the Light section, enable the double-sided option, although this would leave V-Ray having to make direct light calculations for two directions now, which oftentimes is unnecessary. Let's instead use the move tool to flip the light object around by 180 degrees. Taking a test render now reveals the current level of illumination that we have. Now something that we do get by default from an area light such as this are soft-edge shadows.
We can see in the Options section of the light controls though that whilst we can turn the shadows off and on, we have no ability to directly affect the softness of the shadows, which, just as is the case with real-world light objects, will be entirely dependent here on the size of the rectangle light itself, meaning that if we increase the size of the light object, we increase not only the level of illumination coming from it, but also the softness of the shadows that we see as well. Of course, the opposite is then also true. As we decrease the size of the light, we decrease both the level of illumination and we get sharper shadow edges into the bargain.
The rest of the parameters found in the Options rollout give us a great deal of control over how our rectangle light will interact with its surrounding environment. We can as already noted make our light object double-sided. We can make the light invisible, meaning we can control whether or not the light object can be seen in a final render if the light-emitting side is facing the camera, that is. If I were to go ahead and check the invisible option, that of course would no longer be the case, even though nothing about lighting in this scene would change.
You will also notice that we have no decay options here that we can set, because, again, we always get natural inverse square falloff from a rectangle light. In fact, the only alteration we can make in that department would be to enable the no-decay option which would cause illumination coming from the light to travel through the environment without any falloff whatsoever. We have affect diffuse, affect specular, and affect reflection controls that can come in very handy indeed with affect reflections being particularly useful when used in conjunction with the invisible option.
You see, by default, whenever we set our light to be invisible in a render, it will still be visible to reflective materials in the scene, unless, that is, we also uncheck the affect reflections and possibly affect specular boxes. At that point, our light would now be completely invisible, apart of course from the illumination that it would still be giving off. You will have noticed here that we also now, new to V-Ray 3 in SketchUp, have the ability to not only disable the rectangle light contribution to those three material properties but that we can also simply dial these down by means of these slider controls.
This affords us a little extra control over how our light will interact with surfaces in the scene. As you can see then, a very comprehensive set of controls that give us the ability to fine-tune the way in which this powerful light object works inside our environments.
- Gamma handling in V-Ray 3 for SketchUp
- Working with interactive rendering
- V-Ray light types
- Working with irradiance mapping
- Rendering animations
- Working with the V-Ray camera
- Using the Materials UI
- V-Ray FX tools
- Stereoscopic 3D rendering
- Using V-Ray objects