"Candelas Lumens and Lux" introduction to lighting  terms and calculations
"Candelas Lumens and Lux" introduction to lighting  terms and calculations




Viewing Photometric files to show Curves, Solids, Standards etc.

Here is a program which shows your photometric files in 16 different tabs, and each tab shows you a different aspect of you photometry. PhotoView is a photometric software program for viewing photometry files. On opening a file (LDT, IES, OXL etc.) you are initially shown the general data tab:

Viewing Photometric Files

If you need more help or background information to understand and interpret these diagrams and tables then have a look at "Candelas Lumens and Lux":

Candelas Lumens and Lux book cover

Back to PhotoView. On that first dialog you can read and edit these properties of your luminaire:

  1. Code, Name, Manufacturer and so on.
  2. The dimensions of the luminaire.
  3. The dimensions of the luminous area/volume.
  4. The shape of the luminous area/volume
  5. The lamp(s) of the luminaire and property(s).
  6. Data about the measurement of the photometric solid (date of the measurement, name and code of the lamp used).
  7. The symmetry, efficiency, power supply data.

When you click on the other tabs the photometric curve you can see at lower left of the screenshot (above) remains where it is. From now on though I'll only show you the tabs, so you can see them in a bit more detail. The next tab is the table of intensity values. Normally you only view it:

Selecting colors for the photometric curves

Here you can change the colors and thicknesses of the lines when displaying the photometric curves (polar/cartesian/sollner). Right click on the column (C-Plane) or row (Gamma-plane) you want to change. You'll get this dialog:

Photometry Curve Color Linetype and Thickness selection

Of course you can add other planes to the diagrams. (The Polar and Cartesian diagrams are the next two tabs we will look at.)

Note that we are in View Mode (see the radio button in center left above). If we click on the Edit Mode we are able to edit indiviudal intensities as well as change whole rows or columns:

Editing the Photometric file intensity values

In this edit mode you can also

  1. Rotate the photometry.
  2. Copy from left to right, and right to left.
  3. Symmetrize to various alternative symmetries.
  4. Average whole rows or columns.
  5. Interpolate, changing an intermediate column (or row) to be an interpolation between its neighbours.
  6. Add a constant to selected intensity rows or columns.
  7. Multiply selected candela rows or columns with a constant.
  8. Set selected rows or columns to a constant.
  9. Set the efficiency of the photometry to 100%, useful for LED luminaires.

The next tab in PhotoView is the Polar Photometric Diagram tab:

Viewing the polar diagram of a luminaire

The line color and width settings you made in the previous tab appear here. You can save this image as a bitmap (PNG,BMP,JPG etc) or copy it to the Windows clipboard by using the Edit menu. You can even save the image as a DXF or EPS PS vector image. The latter are often used for when you need to create luminaire catalog images.

You can also view the same photometry as a series of gamma-planes by clicking on the View Gamma Levels radio button:

Viewing gamma planes of a photometry file

The next tab is the Cartesian diagram, often used with floodlights and other VH style luminaire photometries:

Viewing the cartesian diagram of a VH floodlight photometric file

Just as with the polar tab you can use the intensity table to change line widths, colors and types, and the edit menu to copy the image to the Windows clipboard. In fact all the images of all the tabs can be copied in this way or saved to image files.

The next tab shows you the "photometric solid":

Viewing the photometric solid of a phtotometry file

The photometric solid image above shows almost all the options in PhotoView for this type of graphic. You can see the C0,C180 etc axes as well as the gamma angle ticks. Also superimposed is the VH grid and the intensity levels shown as circles. You can see that the maximum circle is 200 cd/Klm. Note in the center of the image the black cylinder, which is the volume of the luminaire, the white area is the luminous surface of the luminaire. Lets take a closer look at these with a different photometry:

Viewing the photometric solid of a phtotometry file (annotated details)

The above screenshot also shows the extents of the beam opening. It is the white ellipse below the yellow photometric solid. In this case the luminaire as rotational symmetry, so the ellipse is a circle. In the example below though the beam aperture is assymetrical:

Viewing the photometric solid of a phtotometry file, showing the beam opening aperture

You can also see the black volume of the luminaire and the white light emitting surface at the bottom of it.

Speaking about the beam aperture here is how PhotoView shows that in the next tab:

Beam Opening of CG photometry data

The above example is for CG photometries (3D), but there are also the simpler 2D version. And for VH photometries the diagram is like this:

Beam Opening of VH photometry data

Note that not only are the beam angles given, but also the NEMA standard.

The next PhotoView tab is "Isolux" and shows the direct lighting calculation of one or more of the luminaires in a room or road:

Isolux diagram from a photometry file

There is an automatic choice of colors and lux levels to show, but you can change these at will, as well as fonts and font sizes, the heights and angles of the luminaires etc.

To get a better idea of the light distribution you can activate shading, switch off the contours and switch on the maximum lux points:

Next comes the "luminaire classification" tab which gives you data on:

  • The efficiency of the luminaire.
  • The zonal flux (as figures and a graph).
  • The CIE Flux Codes.
  • D DIN 5040.
  • F UTE.
  • N NBN, BZ.
  • LOR, ULOR and DLOR.
  • UFF, DFF and FFR.
  • RN.

Classification of Luminaires

The UGR (or Unified Glare Rating) tab contains the usual table for this classification, and has an edit box where you can type your own interdistance, but which is usually left at the default of 0.25:

UGR Unified Glare Rating table

There are two road lighting classification tabs, the first one is based on an older way of classifying the photometric data, and the second is based on the US road classification standards. Here is the first tab:

Road Lighting Classification

It repeats some of the data in the classification tab, and adds the standard graphical diagram which shows how much flux flows into the road (on the right in the above screenshot) and how much into the sidewalk (on the left). It also shows Spread and Throw, SLI Glare, CIE and IES classifications.

The Tilting Angle slider allows you to change the tilt angle of the luminaire to send more or less lumens into the road compared with the sidewalk.

The X coordinate units lest you decide whether the x-axis of the diagram is angles or in distance.

The US Road Stadards tab is divided into three sections, and gives you the BUG, LCS and Short Medium Long diagram:

BUG and LCD classification system for road luminaire lighting

As usual with PhotoView images you can change the fonts and font sizes if you have special requirements for your WEB or paper catalogs.

Next we come to two tabs which give us information on glare and luminance. The first one is the Sollner diagram, an example of which is shown below:

Viewing the Sollner glare of a photometry file

Photoview can actually give you more lines than the normal 0° and 90° and if you click on the Multicurve button in this tab you can see all the curves which you have selected in the intensity value table :

Viewing more than one Sollner curves

The next tab is the luminance tab and it gives you a numerical and graphicsl view of the luminance of the luminaire from Gamma=0° to Gamma=90° at all the C-Planes:

Luminance in Photometry files  like IES and LDT

Just as with the polar and cartesian diagrams you can choose colors and linetypes and which planes you want to view.

The next tab creates spacing tables for emergency luminaires. It also gives youa lux profile in any angular direction away from the luminaire. It gives indications of how to space luminaires in corridors and rectangular spaces, as well as LM53 and SHR values:

Spacing tables for emergency luminaires

The red curve above we call the "lux profile" and is how the lux values fall away on the floor of the building in a given direction. You can of course change:

  • Height of the luminaire
  • The angle to view
  • The length of the x-axis in meters

The CIE utilization tab looks like this:

CIE tables of utilization

and gives you the standard CIE tables and calculations. Double clicking on one of the numbers in the K column lets you change the room index for that row, and clicking on the reflection numbers in the top row lets you change those too.

Changing fonts and font sizes.

Use the Options menu, Font Options item to change the various fonts in the graphics of this photometric viewer:

Changing fonts in your photometry images

This is very useful if you are creating images for a catalog or WEB site for example.

The edit menu.

The edit menu of PhotoView has these options:

PhotoView is also great for batch conversion of Photometric files as well as batch creation of Photometric images and data for catalogs.

And remember you can get a deeper understaning of these diagrams and tables by reading the book "Candelas Lumens and Lux":

Candelas Lumens and Lux book cover

Click here for details of discounts on PhotoView, the program which created the images on this page.


(c) 2022 Owen Ransen
Contact me if you have any questions about this page or PhotoView photometric viewer. PhotoView is part of a set of services and programs from OxyTech which can be bought with a 10% discount. Click here to find out more.