I've spent few hours trying to understand how to read Photometic Diagram but still do not understand what written in the website, then I try youtube and found your video which helps me to understand in few minutes. Thank you very much
Thank you so much for this video. I've been studying Cuttle's text on lighting design and hit the section on spatial illumination distribution which made little sense to me until I watched your video. Now the chapter just snapped into focus. Thank you!! 👍
The term Horizontal was selected (i believe, it's been used in the industry for decades) as the base of the cone is projected onto a horizontal plane to be viewed in two dimensions (the red line).
It's honestly very easy to grasp. If you just try to imagine for example a 2x4 with a frosted lens on a type C goniophotometer you would get more rounded distribution, where as if you have a linear prismatic lens on a vapor tight for example it would look more jagged. It is really just about looking at the light distribution in real life and imagining it on a 3D plot. As for polar plots, they give you 0-180 and 90-270 so just understanding where the axis are and how the fixture is mounted in reference to that is a big help
It would be nice to have a quick explanation on the polar graph on the different numbers and what they represent. Also, what illuminance level the colored lines represent. I think the shape is intuitive, but how that translates to a real building with real equipment is what I find confusing.
The plotted lines are intensity in candelas and not illuminance (fc/lux). Illuminance is a function of distance. Divide the intensity in candelas by the square of the distance from source to point to get illuminance :) (uncorrected for horizontal or vertical).
Could you please explain the relationship between the angles and the shape of the vertical plane of light? I see that as you go from 0 + 180 degrees to 30 + 210 degrees and so forth the shape gets wider, but I do not understand how these angles are determined. Basically, when looking at the shape of the light, how can I determine what the angle is?
Why do I not see a "horizontal" cone? To me, a cone that's horizontal would have its base plane perpedicular to a traditional XY plane, with it's point pointing either in the plus or minus X direction. I.E., if you were holding a little wooden cone "horizonatally" in your hand, you'd have the point facing to the left or right. In this video I see no such visual metaphor.
After 12 years, it still helping. Thanks for this video!!!!
I've spent few hours trying to understand how to read Photometic Diagram but still do not understand what written in the website, then I try youtube and found your video which helps me to understand in few minutes.
Thank you very much
Thank you so much for this video. I've been studying Cuttle's text on lighting design and hit the section on spatial illumination distribution which made little sense to me until I watched your video. Now the chapter just snapped into focus. Thank you!! 👍
You are most welcome!
Your link is a MOST helpful example of Lighting Analysts' enduring commitment to serve / help / enable our lighting community. - Paul Coppage,
Thank you for your intuitive and informative explanation.
The term Horizontal was selected (i believe, it's been used in the industry for decades) as the base of the cone is projected onto a horizontal plane to be viewed in two dimensions (the red line).
It's honestly very easy to grasp. If you just try to imagine for example a 2x4 with a frosted lens on a type C goniophotometer you would get more rounded distribution, where as if you have a linear prismatic lens on a vapor tight for example it would look more jagged. It is really just about looking at the light distribution in real life and imagining it on a 3D plot. As for polar plots, they give you 0-180 and 90-270 so just understanding where the axis are and how the fixture is mounted in reference to that is a big help
Excellent!
Thank you so much!
ah top !
It would be nice to have a quick explanation on the polar graph on the different numbers and what they represent. Also, what illuminance level the colored lines represent. I think the shape is intuitive, but how that translates to a real building with real equipment is what I find confusing.
The plotted lines are intensity in candelas and not illuminance (fc/lux). Illuminance is a function of distance. Divide the intensity in candelas by the square of the distance from source to point to get illuminance :) (uncorrected for horizontal or vertical).
Yes! I have yet to see a chart with units on the numbers. Honestly I don't respect charts that don't label units.
Could you please explain the relationship between the angles and the shape of the vertical plane of light? I see that as you go from 0 + 180 degrees to 30 + 210 degrees and so forth the shape gets wider, but I do not understand how these angles are determined. Basically, when looking at the shape of the light, how can I determine what the angle is?
Melanie Prada
vertical section of the 3d photometric data from different angles
Why do I not see a "horizontal" cone? To me, a cone that's horizontal would have its base plane perpedicular to a traditional XY plane, with it's point pointing either in the plus or minus X direction. I.E., if you were holding a little wooden cone "horizonatally" in your hand, you'd have the point facing to the left or right. In this video I see no such visual metaphor.
Awesome! :-)
Our software Photometric Toolbox accepts any IES, LDT or CIB photometric file. Download a Trial version at agi32.com.
Could not get the concept..