Creating Visible Light

In this tutorial we will describe how to create "visible light" using POVRay.

This tutorial assumes familiarity with 3D Canvas and that the 3D Canvas Basics tutorial has been completed. For more information on POVRay see the POVRay tutorial.

bulletDrag and drop a cube onto the scene.

 

 
bulletRight-click on the cube and choose Scale->To Size from the pop-up menu.

Enter the dimensions as shown.
 

 
bulletDrag and drop two more cubes. Use the Scale->To Size function to resize one cube to .1x10x10 and the other to 10x10x.1.

Arrange the three scaled cubes as shown.

 
bulletDrag and drop four cubes as shown.

 
bulletSubtract these cubes from the wall using the Subtract Boolean operation.

To do this, click a cube, then click the  Subtract Boolean operation and then click the wall.

We have our completed scene, a room with a window.

 

 
bulletDrag and drop a spotlight onto your scene. At this point, do not reorient it.

 
bulletDrag and drop cube onto the scene. Use the Scale->To Size function to resize the cube to .1x.1x20.

Position the cube as shown. And move the cube to the same group as the spotlight.

It can be difficult to orient a spotlight using Direct 3D since with Direct3D (and virtually all real-time renderers), light travels through walls. We will be using this resized cube as an aid in directing the spotlight.
 

 
bulletPosition the spotlight as shown so that it shines through the window. Once you are happy with the position and orientation of the spotlight, delete the resized cube.

Right-click on the the spotlight and ensure that "Cast Shadow" is checked.

 
bulletClick the button on the main toolbar to render the scene with POVRay. This will allow you to verify that your spotlight is oriented as shown.

Find any point lights in your scene and de-select "Cast Shadow". Point lights interfere with the visible light created POVRay. Also, to get the best effect your scene should be relatively dark. You may want to reduce the lighting in the scene. To reduce the brightness of a light, right-click on the light and choose Properties. Change the light color to a darker color. This will enhance the appearance of the visible light created by POVRay.
 
 
bulletRight-click on your scene and select Camera->Animation. We are going to be creating a snapshot of the scene and snapshots are recorded using the scene's animation camera.

Position your view of the scene as shown.

 
bulletChoose Properties from the File menu and change the Raytracing Particles color from black to grey. To do this click on the color swatch. This enables particles in the atmosphere for POVRay raytracing. It is these particles that make light visible.

Click OK.

Push the on the main toolbar to enable rendering of atmosphere.

 
bulletCreate a snapshot of your scene using the function of the main toolbar. Be sure to check Raytrace before clicking OK. Also, raytracing scenes with visible light is an extremely slow process. I helps to raytrace at a very small size initially until you are sure that the general appearance of the scene is correct. In this test render we rendered at a custom size of 80x60.
 

 
bulletOur completed scene with visible light.

Note that "visible light" is only visible if there is something behind the "visible light". This is easy for any scene that takes place in the interior of a room. But if you want to have "visible light" in "space" you will need to create a large sphere and place your spotlight and camera inside it. This appears to be a bug in the current version of POVRay. It may be repaired in the future.