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Vlado, you say Vray will have an equivalent lighting analysis tool. Will the USGBC accept it's output for LEED Building accreditation?
In fact, after closer investigation, the answer to this might actually be "yes", as LEED accreditation does not really include any prescriptions on the software being used for building design, so long as the software is capable of predicting lighting levels accurately (which V-Ray can do).
Demonstrate, through computer simulation, that a minimum daylight illumination level of 25 footcandles has been achieved in a minimum of 75% of all regularly occupied areas. Modeling must demonstrate 25 horizontal footcandles under clear sky conditions, at noon, on the equinox, at 30 inches above the floor.
And then, in response to my email:
The LEED® Green Building Rating System™ does not certify, endorse or promote any products, services or companies, nor do we track, list or report data related to products and their environmental qualities. LEED is a certification system that deals with the environmental performance of buildings based on the overall characteristics of the project. We do not award credits based [on] the use of particular products, but rather upon meeting the standards in our Rating Systems. All of our Rating Systems and supporting documentation templates are available for free download at www.usgbc.org/leed. We encourage all product manufacturers or distributors to familiarize themselves with our Rating Systems to see where their product fits and how it might be used to help projects improve sustainability and earn LEED credits.
How does one "demonstrate 25 horizontal footcandles under clear sky conditions, at noon, on the equinox, at 30 inches above the floor?" in a rendering? I mean, how do you look at a rendering, and determine the real-world lighting values, from say a jpeg image?
For the next update, V-Ray provides utilities to visualize and determine the illuminance on surfaces in the scene (through render elements), and also a helper object to determine illuminance at any particular point in the scene.
For the next update, V-Ray provides utilities to visualize and determine the illuminance on surfaces in the scene (through render elements), and also a helper object to determine illuminance at any particular point in the scene.
That's awesome, really looking forward to it. All of this is still rather vague unless we have some accurate way to describe the light reflectance (reflected light not reflections) of surfaces that adheres to some standard. Any work on someting like this?
www.dpict3d.com - "That's a very nice rendering, Dave. I think you've improved a great deal." - HAL9000... At least I have one fan.
This depends on your materials and ideally reflectance information is provided by the manufacturer of particular materials (e.g. wall paint reflectances etc), or otherwise measured for the specific case (one of the many measurements you'll need to do for LEED accreditation ). These values directly translate into the colors for the V-Ray material. We may provide some presets, but for really accurate results, you'd have to use information for the specific project, otherwise the illumination levels are not really meaningful.
Yeah, it seems the only way that one could tell a client a realistic lighting value would be with a helper in the scene. As soon as you do a rendering of the scene, it all becomes relative.
We could do 10 renderings of the same scene, with different shutter speeds, different color mapping, and also tweak the exposure, gamma, and levels in post, and you would get 10 completely different brightnesses of the same scene, none of which reflect the reality of the lighting if a scene were built in the real world. Which is one reason I never bother with IES lighting.
Yeah, it seems the only way that one could tell a client a realistic lighting value would be with a helper in the scene. As soon as you do a rendering of the scene, it all becomes relative.
We could do 10 renderings of the same scene, with different shutter speeds, different color mapping, and also tweak the exposure, gamma, and levels in post, and you would get 10 completely different brightnesses of the same scene, none of which reflect the reality of the lighting if a scene were built in the real world. Which is one reason I never bother with IES lighting.
Exactly right but since it sounds like we're going to be able to extract how much light is hitting a surface this doesn't change like a rendering does. Just like a real world example, you can use a light meter to record the light at a particular point and you are still able to change the exposure values for a real world camera (f-stop, aperature, etc). Getting a pretty rendering has nothing to do with it, but getting an accurate determination of the amount of light is what is important for LEED. In the past these "light level" images were done as a false color image where blues were dark, reds were bright and the scale had some calibrated end points.
So Vlado, without giving too much away, if we set up our scene correctly (proper paint reflectance values, IES lights, etc) will we be able to determine the amount of footcandles on a surface, regardless of the image quality in the rendering (i.e., exposure, sampling, etc).
www.dpict3d.com - "That's a very nice rendering, Dave. I think you've improved a great deal." - HAL9000... At least I have one fan.
Oh, I see. Like an infrared image or something, that is about data, rather than representation. I guess I should read up on the LEED and see what they are expecting.
I have not done these type of renderings, but analogously in terms of real-world simulation, I have done quite a few "Verified Views". Needless to say, once you completely understand the limitations of the system, you realize how much error could be introduced. Often more than you want to vouch for...
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