Eaglerulez Posted January 7, 2021 Share Posted January 7, 2021 Hi there, I am interested in using the Photometer and Photometric grid tools to predict staging light levels. As I was playing around with the tools I was getting footcandle readings that seem to be much higher than listed on the manufacturer's report. For instance at a distance of say 16' when I would expect to get around 300 footcandles (based on the manufacturer's report) I am reading 450 foot candles in Vectorworks. Are there any tips and tricks that I can use to get a more accurate prediction from Vectorworks? I tried playing around with where the photometer was placed (how centered on the beam it was, etc) but still no dice. I don't mind some variance, but it seems like Vectorworks is substantially higher in its predictions than what the manufacturer's report shows and if anything I'd rather have it the other way around. Thank you! Quote Link to comment
Vectorworks, Inc Employee klinzey Posted January 7, 2021 Vectorworks, Inc Employee Share Posted January 7, 2021 Make sure the data you are supplying the Vectorworks symbol is in candle power or peak candella, not Lux, Lumen or some other value. (It does NOT use the value from the VW light emitter.) With that said Vectorworks uses a very simple cosine squared falloff calculation based on the distance from the source. It does not take into account dimmer value, color, shadows, reflections or any other objects in the drawing. 1 Quote Link to comment
Eaglerulez Posted January 7, 2021 Author Share Posted January 7, 2021 2 minutes ago, klinzey said: Make sure the data you are supplying the Vectorworks symbol is in candle power or peak candella, not Lux, Lumen or some other value. (It does NOT use the value from the VW light emitter.) With that said Vectorworks uses a very simple cosine squared falloff calculation based on the distance from the source. It does not take into account dimmer value, color, shadows, reflections or any other objects in the drawing. Hi there, I am using a stock Vectorworks library symbol and have confirmed that it is using candellas. Honestly not looking for Vectorworks to calculate things like color, dimmer value, etc. Just want it to get within spitting range of the manufacturer reports otherwise there's no point in using this functionality. I figure there may be something I am missing in how I have things laid out in Vectorworks? 1 Quote Link to comment
Vectorworks, Inc Employee klinzey Posted January 7, 2021 Vectorworks, Inc Employee Share Posted January 7, 2021 Check the values we have in our symbols. We assume a certain lamp type when we create the symbol and use the data that is available when we created the fixture. I know that some specifications have changed over the years and manufacturers have correct/updated their specification. We have verified that that calculations we report are correct based on the methods in Robert C. Mumm's Photometrics Handbook 2nd Edition. The manufacturer's report probably uses actually measurements so they will always be more accurate. 1 Quote Link to comment
RickR Posted January 10, 2021 Share Posted January 10, 2021 The biggest issues is applying enough 'light loss factors' Manufacturers always list the best possible output. Just about anything will reduce output. Dirt, lamp age, voltage drop, lens scratches, haze... Quote Link to comment
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