Light Sources in Piranesi: Setting a Vertical Cone

Bonnie Roskes
Independent Writer and Consultant

In this example, we want a vertical cone light to project downward from the circular ceiling light fixture onto the balcony.

This type of light is created by a Radial Fade, whose type is 3D Line Source. To define the light's start point, click Pick next to Start.

Start the 3D line source at the center of the light fixture. (Click the point, do not drag to the end point.) Then click End and pick an end point on the floor below the fixture. To see the shape of this light source, uncheck Place centre (if needed), then click Tweak. The shape is a cylinder, but it is probably not exactly vertical.

Press Esc to leave Tweak mode, and click anywhere to create the light. It might look pretty good, but it can be created more accurately.

Since the light is supposed to be projected straight down, we can use known reference points to create the light, then move the light to its correct location. Delete the light created earlier, and start the process again using Radial Fade with type set to 3D Line Source. Click Pick for Start and drag a vertical line to define both the Start and End points. Drag this line along any two points, anywhere on the model that will define a vertical line.

Tweak the light, and drag the radius to enlarge or shrink the cylinder.

To move it into place, move the cursor to the centerline of the cylinder, where it becomes a rectangular symbol. Move it to the balcony light fixture.

Reapply, and the light projects straight down. Depending on how long your cylinder is, the light might not make it all the way to the floor.

For the light to proceed all the way to the floor, check Infinite line and Reapply. Now the light goes to the floor (but not past it). If the beam of light appears too narrow or wide, you can always Tweak it as required.

About the Author

Bonnie Roskes is the author of a number of books on SketchUp, including the recent "Mastering Piranesi: version 4" and "The SketchUp Book: version 5." She is the founder of F1, a technical documentation and training company, which does project work for several CAD/CAM companies such as updating manuals, online help, and creating tutorials. In addition to SketchUp, she has authored books on OneCNC, and Piranesi (soon-to-be released). Bonnie has a BS and MS in structural engineering, and worked for several years in bridge design and analysis before moving to tech writing. She can be reached at: bonnie@f1help.biz.