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The second of our artificial light types to come under examination is the V-Ray rectangle light. Now, this particular light type is extremely versatile and extremely powerful. It really has been designed to mimic real-world light emitters. For this reason, it is probably the light type that we'll want to work with most often. Of course, to make an examination of the light, we need to add it into the scene, so let's come up to our Window menu, down to Layers and in the Layers dialog, let's come and put a check in the Light_Rectangle layer, and that will add our rectangle light into the scene.
Now again, as with our omni-directional light, the first thing we want to do once we have added a new light object into a scene is to take a test render. This will allow us to evaluate both the illumination that we getting in our environment from our new light object and it will also allow us to see what kind of a light-emission pattern we're getting. So let's go across to the V-Ray toolbar and use the Start Render icon to take that test render for ourselves. Of course, straight away we can see that we get a very different light-emission pattern as compared to our omni-directional light, which really is not surprising, as all of the light in the scene is now being emitted from this one side of our rectangular light object.
Now, by its very nature, the rectangle light is a genuine area light and as such, there are just one or two things that we need to keep in mind when we're making use of it. The first is the fact that by default we get natural area, or soft-edge, shadows from this particular light type. If we take a look at the shadows coming from our sample objects here, you can see we don't have that sharp termination anymore; we actually have a nice soft falloff to them. Something else that we need to keep in mind is the fact that when it come the V-Ray rectangle light the size really does matter.
What we mean is that as we increase the size of our Rectangle Light object, we will increase the level of illumination; we'll increase the intensity of light coming from it. This of course is quite natural because as we increase the size of the light object, we are increasing the light-emitting surface that it has. A consequence of the fact that our light is enlarging is also the fact that our shadows will become softer; they will become more diffused in the scene. Of course, the inverse is also true.
As we decrease the size of our light, we'll decrease the level of illumination coming from it, and we will get sharper and sharper shadows. If we make our light very small, we'll get very sharp edge shadows from it indeed. Now of course we're going to want to take a look at the control parameters for our rectangle light, so let's just move our V-Ray Frame Buffer so we can select our light object and then right-click, come down to V-Ray for SketchUp, and click on that Edit Light flyout. Again, this brings up our Light Editor, housing all of the control parameters for this particular light object.
Now, as we want to keep an eye on our test render, I'm just going to move this off to the side once more. Now you'll notice that some of the controls in here are very familiar indeed. In fact, our Intensity controls and our Sampling section are identical to those found on our omni-directional light. Our Shadow setting, if we just scroll up, are very, very similar, except you will notice that our Shadow Radius setting is missing. This is because, as we said, our rectangle light is by default an area light. We always get soft edge shadows from it.
The real difference of course in terms of control parameters is found in this Options section. This set of controls is found on no other light type; only the rectangle light has these options available to it. And as I'm sure you can see, they afford an awful lot of control over how this particular light object will interact with our environment. We can, for instance, make our light object double-sided. This means that instead of emitting light from a single side of our rectangular surface, we'll actually get light emitted from both sides of our light object.
We can also make our light invisible. This means that we can actually disable the ability of V-Ray to render this light inside of the rendered frame window. At this moment in time, we have the rectangular representation of our light in the scene burned into the render. If we check this Invisible option, we will still get all of the illumination from our rectangle light; we just will not see show up as a square or a rectangle inside of the final rendered image. We don't have, you'll notice, any fall off controls.
We have no decay options that we can set. Because this is designed to mimic a real-world light emitter, we get natural light falloff from it by default. The only thing we can do is actually set this No Decay option. This essentially means that light will just continue to travel in our environment. There will be no falloff to it whatsoever. Now down at the bottom, we have some familiar and very important controls in the Affect Diffuse and Affect Specular options. We also have this new one: Affect Reflections. This can be very useful indeed, particularly when used in conjunction with the Invisible option.
By default, if we set our light object to be invisible in our final renders, it would still show up inside of any reflective materials inside of the environment, unless, that is, we uncheck our Affect Reflections box. This means now that essentially our light will be completely invisible in the scene apart from the illumination that it gives off. So, as you can see, a comprehensive set of controls that really allow us to fine-tune how this very powerful light object will work inside of our environment.
So, now that we have an overview of the workings of the V-Ray Rectangle Light, let's move on in our next video to examine another V-Ray's artificial light types, and that is the V-Ray spotlight.
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