Obtrusive Light - Illuminance/Intensity

The function of the Obtrusive Light - Illuminance/Intensity command is to compute illuminance and tabulate intensity in candela at points in a vertical plane some distance from the lighted area. This is used to evaluate objectionable light on neighboring properties. This command allows for both the illuminance points and the intensity points to be created using one command. The calculation of luminous intensity is based on the ability of each calculation point to measure the intensity from each luminaire on the site. Only the maximum value tabulated is displayed. The offending luminaire from which this intensity value is measured can be identified with the keystroke, Ctrl-L when the intensity points are visible (switch visibility in Project Manager).

The locations of the vertical planes, the pre-curfew and post-curfew limits for illuminance, and the maximum allowed luminous intensity values (candelas) are specified by obtrusive light standards CIE 150:2017 and AS 4282-2019.

Using the command:

  1. From the main menu bar, click Add, then Calculations, Obtrusive Light, and finally Vertical Illuminance/Intensity. Or in the Calculations Toolkit, click the down-arrow next to the Obtrusive Light button and select Illuminance/Intensity.
  2. Enter a Label, and a Description if desired. The default label will be ObtrusiveLight_1. Unless changed, subsequent labels will be ObtrusiveLight_2, ObtrusiveLight_3, etc. If a number is used for the label, subsequent labels will be incremented accordingly.
  3. Set the Point Spacing. The Text Size will be adjusted according to the Point Spacing, but its value can be changed if desired. The relevant Standard should be consulted as the required or recommended point spacing in the grids.
  4. You may choose to Center the Points in the grid in the left-to-right and/or top-to-bottom direction. Centering is applied to each segment of the line individually. If a line segment is shorter than the point spacing, one point will be placed in the center of the segment. Note: Centering points top to bottom means that the bottom row of points will not be at the height of Z-Coord-Bottom, and the top row will not be at Z-Coord-Top. Similarly, centering points left to right means that the first and last points in the grid will not coincide with the beginning and end of the line. If Centering is not selected, the first point will coincide with the beginning of the first segment and at the Z-Coord-Bottom, with the rest placed according to the set Spacings.
  5. Set the values for the Z Coordinate for the top and bottom of the grid.
  6. For the Calculation Type, select the metric(s) that you wish to calculate. Illuminance and Maximum Luminous Intensity are both selected by default.
  7. For Illuminance, Vertical Grids is selected by default. Alternatively, you may select Enclosed Box.
  8. Since the Vertical Illuminance points and the points on the sides of the Enclosed Box are in a vertical plane, the meter direction will be perpendicular to the plane. There are two possibilities here, Perpendicular (CW) and Perpendicular (CCW). The reference here is clockwise or counterclockwise rotation from the line to get to the perpendicular direction. For example, if Perpendicular (CW) is selected for the meter direction and then the line is drawn from west to east, the meter direction will be south. (After drawing the line, the meter will be shown, and if you wish to change it you may do so without returning to the dialog by pressing F5.) Note: For the Enclosed Box option, the meter direction will be inward regardless of whether CW or CCW is selected here.
  9. In the Summary section, select what you wish to include in the calculations.
  10. In the Display Options section, you may set the number of decimals to display for Vertical Illuminance and for Luminous Intensity. You may change the color of the grid here, and set any Labeling option desired. By default, the points themselves, the line they are associated with, and the Meter Indicator (showing the direction of the light meter) will be displayed when the line is drawn or selected from an existing drawing entity, but they may be de-selected here if you don't wish for them to be displayed.
  11. Select whether you will Manually Specify the Line or Select an Existing Drawing Entity to define the calculation points.
  12. If you would like Isolines or Highlighted Values to be shown on the grid after it is calculated, you may specify them from this dialog by clicking on the Isolines button or the Highlight button.
  13. Click OK to exit the dialog.
  14. Now you are ready to specify the line, by either drawing it or selecting an existing line. If drawn manually, click the first point and then subsequent points (vertices) as appropriate.  The line may be composed of multiple segments. After clicking on the last point, right click to end the command.
  15. If an existing drawing entity was selected, AGi32 will display it as bold. If it is correct, press Enter or right click. Pressing Esc will cancel the command. Clicking the Undo button (or pressing Ctrl-Z on the keyboard) will allow you to select again.
  16. The Light Meter's tentative direction will be shown. You may press the F5 key on your keyboard to flip the direction the other way. Press Enter or right click your mouse to accept the direction.

AGi32 will create the grid(s) of points. They will be located above the line drawn or selected, with the bottom of the grid at or above the Z Coordinate that was specified in the dialog, depending on whether Center Points Top-to-Bottom was selected.

The values displayed are vertical illuminance, except on the top of the Enclosed Box if that option was selected. The Light Meter's directional indicator will be shown as a short vector line attached to each point, unless the box for Meter Indicator was unchecked in the dialog.

Changing what is displayed

By default, the Illuminance values are displayed in Model Mode. You may display the Luminous Intensity values (if selected) using Project Manager:

  1. Click on the Project Manager button. (If you have never opened Project Manager before, read the Hint that pops up, and then close it.)
  2. In the upper part of the Project Manager dialog, place a checkmark in box to load Project_1. This is the project you're working on, unless you have renamed it.
  3. In the lower portion of the dialog, select CalcPts from the Entity Type menu. Notice that in the Vis column, the Illuminance grids (ObtrusiveLight_Ill_Seg1, etc.) are checked, but the Luminous Intensity grids (ObtrusiveLight_Cd_Seg1, etc.) are not checked. This is the "visibility" column. Grids that are checked here are visible (displayed) in Model Mode.
  4. Uncheck the illuminance grid boxes and check the intensity grid boxes in the Vis column.
  5. Click OK to exit Project Manager.
  6. What is displayed now are the Luminous Intensity grids. Each displayed value is the maximum luminous intensity directed at that point by any one of the luminaires visible to it on the site. Luminaires behind obstructions (from the perspective of the calculation point) are not considered.
  7. To display the Luminaire Number for the luminaire responsible for the maximum candela value at each point, on the main menu bar, click on Add, then Calculation, Obtrusive Light, and finally Toggle Cd/Lum# Display. Or, in the Calculations Toolkit, click the down-arrow next to the Obtrusive Light button and select Toggle Cd/Lum# Display. Or, use the keyboard shortcut Ctrl-L.
  8. You may use this button or keyboard shortcut to toggle back and forth between the maximum candela values and the Luminaire Numbers of the luminaires that cause them.

Compatibility with earlier AGi32 versions: Obtrusive Light standards and calculations have changed significantly over the life of AGi32. Backward compatibility is limited.