Copyright Goodheart-Willcox Co., Inc. 496 AutoCAD and Its Applications—Advanced Weblight A photometric weblight is really just a targeted point light. The difference is that a weblight provides a more precise representation of the light. Real-world lights appear to evenly illuminate from their source, but, in reality, the shape of the light, the mate- rial used in its manufacture, and other factors make all lights distribute their energy in different ways. These data are provided by light manufacturers in the form of light distribution data. Light distribution data can be loaded into the Photometric Web subcategory of the General category in the Properties palette when the light is selected. Select the Web file property, then pick the button to the right and select an IES fi le. IES stands for Illuminating Engineering Society. The AutoCAD help documentation has additional information on IES fi les. Think of the web of a weblight as a spherical cage surrounding the light source. If the light is evenly distributed from its source, the cage is a true sphere. In actuality, a light may emit more light energy in the X direction than in the Z direction. In this case, the cage bulges out further in the X direction. The position of this bulge may be important to the illumination of the scene and you may need to rotate the web to apply more or less light in one direction or another. The WEBLIGHT or LIGHT command is used to create a weblight. You are prompted for source and target locations. The Name, Intensity Factor, Status, Photometry, Shadow, and Filter Color options work the same as the corresponding options for the previously discussed lights. However, weblights have an additional Web option. When this option is activated, these options are presented: • File. Allows you to select an IES fi le. • X. Rotates the web around the X axis. • Y. Rotates the web around the Y axis. • Z. Rotates the web around the Z axis. • Exit. Exits the Web option. Point and spotlights can be converted to weblights, and vice versa, using the Properties palette. Simply select an existing light and open the Properties palette. In the General category, the Type property determines whether the light is a point light, spotlight, or weblight. Select the type in the drop-down list. Using the Properties palette with lights is discussed in detail later in this chapter. Free Weblight A free weblight is the same as a standard weblight except there is no target. Only the source location is specifi ed when placing the light. To change the location and direction of the light, use the ROTATE3D and 3DMOVE commands. Photometric Lights Tool Palette Group Photometric lights may be easily added to the drawing using the tool palettes in the Photometric Lights tool palette group. This palette group contains four palettes: Fluorescent, High Intensity Discharge, Incandescent, and Low Pressure Sodium. Lights created with these tools have preset properties for Intensity Factor and Filter Color. The long fl uorescent lights are weblights. The high intensity discharge, low-pressure sodium, and regular incandescent lights are point lights. The incandescent halogen lights are free spotlights. The recessed incandescent lights are a special weblight designed for recessed light fi xtures. Lights in Model and Properties Palettes The Lights in Model palette is extremely useful for controlling the lights in your scene, Figure 18-16. Using the Lights in Model palette in conjunction with the Properties palette, you can manage and edit all of the lights in a scene. WEBLIGHT Ribbon Visualize Lights Weblight Type WEBLIGHT LIGHT FREEWEB Type FREEWEB LIGHT