Calculate General Photometrics

The Calculation General Photometrics command is used to calculate point-by-point photometrics inside of general calculation areas. All of the settings available in the command are the same as the Calculate Egress Photometrics command. This sections describes the options available for these two commands.

The two commands use different light fixtures and different settings on the light fixtures. See the General versus Egress Photometrics section for more information on these differences.

To run general photometric calculations, go to

DM Electrical->Point-by-Point Photometrics->Calculate General Photometrics

Calculate Photometrics Dialog Box

Point-by-Point Photometrics--Calculate Photometrics dialog box

Contour Level 1 - 10: Enter the footcandle level to draw contours at. You can have up to 10 contours. Contours set to 0 will not be drawn.

Show FC Levels: Whether or not footcandle levels are shown on the drawing. If this is checked, the footcandle levels will be displayed in the calculation area after the calculation is finished.

Show Contours: Whether or not contours are shown on the drawing. If this is checked, contours will be displayed in the calculation area after the calculation is finished.

Decimal Places on Drawing: The number of decimals to include in the footcandle levels on the drawing.

Decimal Places in Schedule: The number of decimals to include in the footcandle levels on the schedule. If the Decimal Places on Drawing is less than the Decimal Places in Schedule, the smaller Decimal Places on Drawing will be used for the Maximum Foot Candles and the Minimum Foot Candles values in the schedule.

Base Unit: Whether the base unit for your drawing is an inch or a foot.

Inch: One unit on the drawing corresponds to one inch. The standard base unit for architectural drawings.
Foot: One unit on the drawing corresponds to one foot. The standard base unit for civil drawings.

If you are uncertain which setting to use, go to your drawing in AutoCAD. Type UNITS at the command line. Note the current Type setting, then change it to Decimal. Ignore the Insertion scale setting. It might be set to Feet or Inches, but it is not a reliable means of determine which setting to use for photometric calculations. Press OK to close the dialog.

Type DIST at the command line and measure the distance of an item you know the length of on your drawing. A parking space, door on the building, or total length of the site are all examples of items you could measure.

The distance will be displayed on the command line. Press F2 to view the AutoCAD Text Window if the distance is not visible. You then have to answer the question--is the listed distance in feet or in inches? Based upon the item you choose to measure, you should be able to answer this question. Use this answer to set the Base Unit setting.

Use the UNITS command to reset your Type setting if desired.

Reflections: Whether or not the calculation includes reflections from walls and ceilings.

No Reflection: No reflections are included in the calculation. This choice is faster, though the calculated values will be slightly lower than reality for inside calculations and near walls outside.
Single Reflection: Light is reflected once during the calculations. This choice takes longer, but results in higher values near solids. The light is reflected off one surface to the ground. Light that hits a second surface is not reflected. For example, light that goes from the light, to a wall, to the ground is included. Light that goes from the light, to the floor, to a wall, and back to the floor is not included.

Zoom to Schedule After Insertion: Whether or not the current view will be moved to the schedule associated with the calculation area.

Edit Title, Column Labels, and Column Order: Press this button to modify the layout of the photometric schedule on the drawing. See the Edit Calculation Schedule List section for more information.

Calculating Photometrics

After all the information has been entered, press the OK button.

If there is only one calculation area in the drawing, the footcandle levels in the area will be calculated.

If there is more than one calculation area in the drawing, you will be prompted to specify which area to calculate.

Specify point inside boundary to calculate / <Calculate all boundaries>:

Select a point inside an area to calculate the footcandle levels in just that area. Press ENTER to calculate the footcandle levels in all areas on the drawing.

The footcandle levels and contours in the area that is calculated will be updated. The values in the corresponding photometric calculation schedule will also be updated.


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