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Calculation of Lighting Levels?

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Is VW capable of calculating accurate lighting levels (footcandles, lumens, or other units?) I have looked through the VW documentation and this forum but haven't been able to find anything.

If VW doesn't do this, what software do any of you out there use to determine if your lighting and daylighting schemes are generating sufficient light?

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Thanks, Chris. I assume that your spreadsheets don't calculate actual lighting levels - do you have any experience exporting VW models to other tools for this kind of analysis?

I'm just starting with VW but it looks like it has most of what I need to do informal evaluation of different lighting schemes. I assume that I'll be able to do renderings of various scenarios that will allow me to compare relative lighting levels. I think that these renderings will be fine as design tools and for presenting to clients. The next step, though, is having confidence that the renderings show "accurate" lighting levels and having data showing exact lighting levels at given points throughout the space.

Then there's daylight analysis. I'd love to be able to do accurate daylighting analysis in addition to the electric lighting but I don't know how accurate the VW solar animations are or if HDRI images will allow me to create accurate results.

Any input from you or any forum members on these topics would be greatly appreciated.

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Chris, I think that I get your point - Data is King... and an iterative approach is best but, ultimately, I do need to have some level of confidence that lighting levels (lumens, lux, etc.) provided at work surfaces will be sufficient AND I need to have some way of communicating the feel of a scheme to my client (rendered perspectives, etc.)

I'm certainly not opposed to starting the lighting design with a more mathematical model to determine appropriate lighting levels and then feeding that back into VW for the rendering. What I'm really after is a more seamless way to go back and forth between analysis, presentation, and documentation - with the least amount of rework.

I started this thread after attending a great day-lighting seminar where they presented these great rendered views with overlays of actual lighting data (showing how many lumens, lux, etc. were present in each part of the scene.) That got me to wondering what kind of software was out there that might be able to help me get away from the guess and cross your fingers method typically used on small projects (that can't afford lighting designers.)

Do you have any software or other "mathematical models" that you use for lighting analysis? I'm really hoping to find something relatively simple that will allow me to better predict lighting performance that I can easily integrate into my workflow.


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Michael, OK - NOW WE'RE TALKING! That sounds like just what I'm looking for. Do you know if it works with all types of light sources - not just spotlights?

I don't know. You might want to post the question in the VectorWorks Spotlight forum. I just know it's available.

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It looks like the Photometric grid is exactly what I need but it doesn't appear to work with anything but spotlight ETC instruments. What I need is for it to work with architectural lighting symbols like the "Accurate Lamps" provided with VW.

Does anyone know if there is a way for me to make he photo grid work with other lighting symbols?


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  • Vectorworks, Inc Employee

The photometer and Photo grid use a simple cosine drop-off algorithm and support only Spotlight instruments. They are intended for simple first-cut studio lighting levels.

Accurate architectural lighting (particularly daylighting studies) are a couple of orders of magnitude more complex. (e.g., not only do you have to have the lighting instruments described to a good level of detail, you also need glass transparency, shading factors, accurate sky dome illumination, and accurate color and reflectivity of all your interior surfaces. Whew!) We're looking into how to begin to solve these kinds of problems (possibly tied into RenderWorks' Radiosity capabilities).

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Thanks, Robert.

I was afraid that was the case. I did a little testing over the weekend and discovered that the photo grid wouldn't calculate indirect lighting. I was hoping that it was already tied to Renderworks.

Renderworks is built around LightWork - right? Well, it looks like LightWork is also part of Lumen Designer (formerly Lumen Micro - http://www.lightwork.com/news/pr.php?id=92 ). Is there any chance that most of what is needed for lighting analysis already exists in Renderworks? At a minimum, easy export/import between Lumen Designer would be a great start.

I've also been looking into Radiance ( http://radsite.lbl.gov/radiance/HOME.html ) which is free, will run on OS X, and is reputed to be the most accurate lighting simulator. Easy export to Radiance would also bee great.

Thanks all for the help.

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"Renderworks is built around LightWork - right? Well, it looks like LightWork is also part of Lumen Designer (formerly Lumen Micro - http://www.lightwork.com/news/pr.php?id=92 ). Is there any chance that most of what is needed for lighting analysis already exists in Renderworks? At a minimum, easy export/import between Lumen Designer would be a great start. "

Interesting point Bill. I have been using lighting manufacturers photometric data files within Vectorworks for a few years now. At the recent UK CU event I did request that instead of producing a full render could Vectorworks be set up with a calculation grid with light level (lux) readings. This would be a great advantage when producing concept designs.

I am guessing if the calculation are made to produce the render then the maths is already there to produce calculations.

For lighting designers this would be a great addition to VW. I would then have no need to go to other programs for my calculations.

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vecorspark, how have you been using photometric data? Are you simply plugging the manufacturer's numbers into a symbol or lighting instrument for use in renderings?

Your request for photometric grid is exactly what I'd like to see (perhaps as a rendering option.) VW already has some of what I'm looking for in the existing photo grid tool. If it could give me data for indirect light and daylight contribution, I'd be thrilled.

Hopefully someone at VW is reading this post and looking into it.

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  • Vectorworks, Inc Employee

You can use .ies file to render the light. Set the light type to custom and it will prompt you to select a file.

This will let you render the light to show what it looks like, but it still will not give you numeric values for the lighting levels.

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I am glad you feel that this would be a valuable tool too. As mentioned earlier I have asked for this feature on a few previous occasions.

If more of us out there request, maybe NNA could incorporate it in a future release.

While we are on the electrical side of things (which I know this thread isn't) UK and EU conduit size calculations and metric cable sizes would be great. Then all my electrical requirements could be met within VW. I can see the US system is in there already.

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