Example: Analyzing the Reflectivity of a Lamp Shade
Summary: This example shows how to use a UDA to analyze some reflection properties of a lamp shade.
Problem: Need to analyze the angle at which the light is reflected from of the surfaces of a lamp shade.
Solution: Measure the reflection angle using the analysis features. Then you can create a UDA to apply the value of the reflection angle to the entire surface.
The next figure shows the lamp shade part.
The next illustration shows the geometrical construction that is required to measure the reflectivity angle.
1. The angle between incident light and the central axis.
2. The angle between incident light and the surface normal at the field point.
3. The reflection angle.
4. The equal angle to angle 2.
In this diagram:
• Thick blue line – Contour of a lamp shade.
• Red line – Incident light originating at the bulb point PNT0 and reflected off the surface at the field point FPNT1.
Follow these basic steps to create the UDA:
1. Create all necessary geometry to make the measurement:
a. Create a central axis A_1 through the bulb point PNT0 in a vertical downward direction.
b. Create a field point FPNT1 on the surface whose reflectivity you want to analyze.
c. Create an axis SURF_NORM through this field point normal to the surface.
d. Create an axis from the bulb PNT0 to the field point.
2. Create an analysis feature to measure angle1 (the angle between incident light and the central axis).
3. Create an analysis feature to measure angle2 (the angle between incident light and the surface normal at the field point).
4. Create an analysis feature of the relation type to measure the reflectivity angle using the following relation: ref_angle = angle3 = 2 * angle2 - angle1
5. Create a UDA Construction group by grouping features starting from the field point and concluding with the last analysis feature (reflection angle measurement).
6. Create a UDA to measure the reflection angle on a selected surface. Select the parameter to calculate ref_angle and click Compute. The next figure shows the results of the computation: the portion of the surface highlighted in blue indicates the smallest reflection angles.
7. To analyze another surface for reflectivity, clear the Default option in the UDA dialog box. To specify new references, select a surface, select the bulb point PNT0, and the central axis A_1.
The next figure shows the graphical results of the UDA.
