AutoCAD 3D Modeling: Spotlight

August 20, 2004

Spotlights are conical lights that can simulate headlights of cars, shade lamps, and so on. Every spotlight consists of two major angles called Hotspot and Falloff. The Hotspot angle defines that portion of light cross-section that retains a fix light intensity. The light intensity drops to zero within the Falloff angle. The Falloff angle is always greater than Hotspot. The spotlight can cast shadow. You need to define a target point along with a location point to define direction and location of the spotlight. The following tutorial shows you a sample.

Notes:
► I have used AutoCAD 2005 for this tutorial. However, you may use another release of AutoCAD.
► User entries are in boldface.
► The 8 symbol represents pressing Enter.

1. Download and open the 16_spotlight.dwg file. The file displays a shade lamp at the corner of a room [Figure 1].

Figure 1

Note: If you are using AutoCAD 2002 or an older version download r15_spotlight.

2. Render the drawing (choose View > Render > Render). The rendered image appears on screen [Figure 2].

Figure 2

3. Invoke the LIGHT command (choose View > Render > Light). The Lights dialog box appears [Figure 3].

Figure 3

4. From the list next to the New button select Spotlight. Click New. The New Spotlight dialog box appears [Figure 4].

Figure 4

5. Type S or another name in Light Name box. Highlight the intensity value and type 100. Change the Hotspot and Falloff values to 30 and 45 respectively. Select the Shadow On check box [Figure 5].

Figure 5

6. Under Position area, click Modify. The dialog box disappears. In command line enter target and location points as follows:

Enter light target <current>: 0,0,0 8
Enter light location <current>: 0,0,125 8

7. Click OK in both dialog boxes to close them.

8. Render the scene again (choose View > Render > Render). The spotlight effect appears [Figure 6].

Figure 6

9. Invoke the LIGHT command once more (choose View > Render > Light). From the list of lights click S – the spotlight name – and then click Modify.

10. In Modify Spotlight dialog box under Shadows area clear the Shadow On check box.

11. In both dialog boxes click OK. Render the scene again (choose View > Render > Render). The spotlight does not cast shadow anymore [Figure 7].

Figure 7

12. Close the file. Don’t save it.

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