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When rendering with Twilight in SketchUp, especially if we are producing architectural visualizations, there is a very high likelihood that we will need to create or re-create artificial light sources for our renders. To help with this area, Twilight gives us two specific light types that can cover many artificial lighting situations. We will in this instance be once again working with an artificially darkened start scene. This means that we can keep test renders very straightforward, in that the illumination we see in them will be coming only from the light type under consideration.
So, if we just come up to our Twilight toolbar, you can see that we have two icons that allow us essentially to create our two light types in the scene: we have a Point Light icon and a Spot Light icon. In this video we're going to focus on using our Point or Omni light type. To make a start, we just want to come over to our Window menu and then come down and select the Layers option. This of course will bring up the Layers dialog for us. Down towards the bottom, you can see we have two light layers already set up. We have a Light_Spot and a Light_Point layer. As we said, we want to work with a Point light, so let's put a check in the box, and you can see that brings a point light into the scene for us.
To access its control parameters we can indeed come to the toolbar and click on the Light Editor icon. We would want to have our light object selected first though, because then when we open up the Light Editor, you can see we get taken straight into our light controls. Another way to access this Light Editor would be to simply select and then right-click on our light, come down to the Twilight entry, and then click on the Edit Light option from the flyout. Generally speaking, whenever we add a new light object into a scene, we want to take a test render.
Really, we want a render of that light in isolation. We really want to see what kind of light contribution it is making to the scene, and we want to get an idea of the kind of emission pattern that is coming from our new light type. So we're going to do just that. First of all I'll just grab my Light Editor and just move it off to one side of the SketchUp interface. We'll come up to the Twilight toolbar, open up our Render dialog, and then click on the Start render icon to take a test render. In this instance because we have an object selected in the scene, we have a choice to make: Do we want to render only the selected object or do we want to render the entire scene? As we want to render the entire scene, I'm just going to select No from this dialog and let our test render run.
Straight away, because we are rendering only this one particular light object in the scene, we get a very good idea of the light contribution it is making. We can see that it does indeed cast omnidirectional light into the scene. We can even see the general emission pattern captured on this 2D surface of our upright shelving unit. Now, at this moment in time we are probably making it a little harder for ourselves to see the emission than is necessary, so let's go over to the Camera tab and we'll just drop our Exposure value down a little bit. Let's set it down to something around about 1.4.
That way we just can see the contrast in the scene a little bit more clearly. And let's set our Gamma value to its default of 1. Now we can see that we have this very bright spot where the center of the light object is, and then we see the falloff of light emission as the light travels away from the emitting object. Very rarely though we are going to want to accept just the defaults for a new light type that we have placed in the scene, so again, let's click on our Light Editor icon, just to bring that to the fore, and have a look at this light type's control parameters, which, as you can see, are very much self-explanatory. One option we do want to highlight is the fact that we can name our light types.
We really want to do this as we're adding new lights into the scene. A nice descriptive name can go a long way towards easing the frustration of working with many light objects in our environments. So we can, as you can see, also enable and disable our light type. We can set it to cast or not cast shadows as the need may be, and we can get realistic behavior from those shadows by checking the Soft (Blurred) Shadows option. And of course we can use the color swatch to set the color of the light in the scene. One very important set of controls are these Attenuation options. These essentially control the falloff of our light.
By default, we have InverseSquared set, which give us realistic light behavior. This is how a light will act in the real world. But if we access the dropdown, you can see we do have a couple of other options available to us, should we need to use those in our scenes. Light Strength is, as we've said, a very self-explanatory title for this particular control; it will determine the intensity of illumination coming from our light. We also have this Light Bulb Size or Radius option. This controls really the softness of the shadows that we get from our light type. Higher values will give us softer blurrier shadows; decreased values will naturally give us sharper, cleaner or crisper raytrace shadows.
We do need to know that this value will not change the intensity or the strength of light in our scene. That's why we have a separate control for that. All it will do is determine how the shadows are working. In fact, to demonstrate how this control works, let's set a value of 20 in here. Now we're going to take a note of the shadow edges that we have in the scene at this moment, in time particular the shelving unit and of our test objects. And again, we want to select No from our selection option. And you can see we do indeed make quite a difference to the edges of our shadows. Our light intensity of course remains unchanged, but the blurriness of shadow edges has increased quite considerably--not just on the large object.
You can see our sample spheres here. Even though they are closer to our light source, they still have a much softer edge to the shadows. At this moment in time, our Light Editor controls are of course only affecting the Point light that we have in the scene. These are Point-Light-specific controls. Importantly though, you will see that these controls are also available on each of our other light types. Becoming very familiar with these controls then becomes fairly important when it comes to working with artificial lighting in our Twilight and SketchUp scenes.
Now whilst the Point light type can come in handy in certain lighting situations, the fact that it casts light in all directions makes it firstly harder to control in terms of adding light only to specific areas of our scene, and secondly, the extra lighting calculations it will require will probably add to our render times. For those reasons, in many artificial lighting situations, a more useful light type would probably be Twilight's Spot Light option. This is the light object that we will consider in our next video.
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