Learn how to apply a texture to a quad light.
- [Instructor] One way to control the color and pattern of light is to map it with a texture. We'll use that technique to customize the look of the ambient backlight. For illustration purposes to make it easier to see, I've got a test object in the scene that's currently hidden. Let's go into the layer explorer and unhide the test layer, and tumble around in the perspective view with ALT and middle mouse. That's the test object, that will receive the light.
So now let's take a look at that in the active shade, I'll close the layer explorer, with the perspective view selected. Go into render setup, and just to make sure that we're rendering the perspective view we can toggle the lock button off and on again, and click the render button. Now we're seeing that test object receiving the light from our backlight object. Let's select that backlight, go over to the modify panel, and in the color/intensity section we can choose an option for the light that emanates from the object.
We can set a simple color. We can use a color temperature preset. We can type in a Kelvin value for the color temperature directly, or we can use a texture. So let's enable the texture button, and now the no map button is available. Click on that button. The material map browser opens up. Double click bitmap. Now we have the select bitmap image file dialogue, and in the current projects, sceneassets\images, scroll down near the bottom, and you'll see one labeled: WyEast_sRGBlinear_2k.exr select that, and click open.
Now we see the open exr configuration dialogue, and we don't need to change anything in here, we are not color correcting the map, so go ahead and click okay. And now we see some color and pattern on the test object. With the light still selected let's go back into the modify panel, and reduce the spread down to zero, just type in a zero, and now the light is focused very cleanly on that surface. But it's overexposed so if we want to see that better, we can bring the exposure down in the intensity section, set that to negative four, and now that's a properly exposed image on that test object.
Now that we've seen how those parameters work we can hide the test object and go back to our camera view. Go into the layer explorer once again, and hide the test layer, click on the I icon, close the layer explorer. In the render setup we can unlock the view to render and then select the camera view port. And now we're seeing in our active shade window, the physical camera render. We can lock that, select the light once again, back in the modify panel, change the exposure back to negative one.
Now we've got a little bit of light in here but it's not working very well because our spread is set to zero. So we want that light to suffuse evenly through the environment. We'll bring the spread up to one once again. And now we've got a nice blue light coming through the window, and the color of that light is of course derived from the bitmap. And that's how to apply a texture to a quad light.
- Arnold rendering concepts
- Arnold lights such as quad, spot, and distant
- Modifying Arnold object properties
- Filtering light with the gobo filter modifier
- Image-based lighting with Skydome
- Daylight simulation with Physical Sky
- Arnold Standard Surface material parameters
- Diffuse, opacity, and bump mapping
- Rendering refractions with Transmission
- Building an Arnold shading network
- Test rendering with utility map
- Mesh subdivision and displacement at render time
- Atmospheric perspective with scene environment fog
- Rendering a spherical environment with VR Camera