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INSIGHT BLOG

Who is this for: Architects and engineers interested in daylighting and electric lighting illuminance renderings.

Takeaway: Did you know that Autodesk 360 Rendering allows you to create daylighting and electric lighting illuminance renderings just like other industry-standard daylighting analysis tools like Radiance/DIVA, Autodesk 3ds Max , and IES-VE, but in a fraction of the time, and without interrupting your current Revit workflow?

 

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Luminance (Visual) Rendering

 

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Illuminance Rendering

 

By: David Scheer – Green Building Studio Product Owner

Since January this year, this little known feature has been available through a somewhat hidden dialog on the Autodesk 360 Rendering web portal for any cloud-rendered 3d view sent from Revit 2012+, Vasari or AutoCAD 2013+.

How do I get it?

To use this feature, start by simply rendering any 3d view from Revit 2012 and up, Vasari, or AutoCAD 2013 and up (or if you’re really motivated, by calling the public API) using the Render in Cloud to initiate the cloud service, then go to the Autodesk 360 Rendering web portal at rendering.360.autodesk.com or by clicking on Render Gallery in the toolbar.

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RaaS Render In Cloud dialog in Revit 2012+ and AutoCAD 2013+

In the Render Gallery, a number of options are available by hovering over the thumbnail view. Clicking on the down arrow (clip_image008) that appears in the lower right hand corner of the image will bring up a menu of additional choices, allowing you to re-process the model rendering. One option you will see is ‘Render As…’ Selecting this option exposes the new ‘Illuminance’ setting. Select that setting, and in a few minutes you will have a rendering of illuminance, showing the intensity of light, or the luminous flux in lumens per square meter, or lux from sun or electric light falling on the surfaces in your 3d view.

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We will talk more about the Autodesk 360 Rendering service and the render settings available in Revit, Vasari, and AutoCAD in next week’s post. If you want to get a jump on that topic, visit the Autodesk wiki help site at wikihelp.autodesk.com, check out this really nice article by one of our German partners, watch the intro video and review the resources at the Autodesk 360 Services & Support site, or just go to the View menu, find the ‘Render in Cloud’ button and start playing around. While this feature is in research mode, the Illuminance renderings are offered at very low cost.

Rendering options

The Rendering setup uses the same daylighting and electric lighting models that are used for the visual rendering for the time being. While the electric light model is the same as Radiance and other industry standard tools, and uses the fixture and lamp photometric models, if included, the sun light (daylight) model is slightly simplified. To be consistent for visual renderings, the sun light (daylighting) distribution is modeled using the Preetham sky model, which assumes a clear sky and no aerosol effects like fog or haze. The underlying algorithm for this model is similar to the more advanced Perez model, but the heuristics assume standard solar response and therefore do not use solar radiation or illuminance values from a weather file.

How good is it?

In another article coming to this site in a couple weeks, we will talk about the technical validation work that has been done on the illuminance output from the Autodesk 360 Rendering engine. For the moment, we can say that the engine has been validated with the help of one of the top daylighting firms in the country by comparing our cloud rendering output using the same model rendered in the industry standard lighting simulation tool Radiance, as well as to the actual space measured in the real world.

Results of the validation tests are strikingly similar in all ways but one…the time it takes to create the rendering. When we asked about the level of quality used in the Radiance rendering and how much time it took, the answer was: 5 bounces and it took about 4 hours to render. When we asked the cloud rendering technician how many bounces, the answer was ‘all of them’, and the rendering took about 10 minutes.

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Like any simulation tool, the results are subject to the GIGO rule (garbage in = garbage out). Our goal is to make it much easier, much faster, and more transparent for both novices and professional daylighting experts to accomplish valid lighting/daylighting simulations and renderings. We are doing the work to provide a valid simulation engine and a fast, integrated BIM environment to set up and control the model configuration. We are aware of the pitfalls that can invalidate a simulation model and are working to make it easier to control that risk with transparent UI and intelligent defaults. We will discuss more about what those limitations are in the upcoming validation article. Meanwhile, we would love to hear more feedback from you on how to make your simulation jobs easier and more risk free.

How much does it cost?

Autodesk 360 Rendering is a fee service working on cloud credits. Although you can still use the service at no charge for any ‘basic’ rendering at ‘Standard’ quality and less than 1000×1000 pixels in size, illuminance is considered a premium service and there is a modest charge for it. Basically an illuminance image will set you back a single cloud credit for each megapixel in your image. For more details on how cloud credits work for cloud rendering, see the online help topic.

So don’t wait days for a specialist to give you feedback on your daylighting performance, get an illuminance rendering in just a few minutes on your existing Revit, Vasari or AutoCAD model through your normal Revit workflow with Autodesk 360 Rendering. 

UPDATE April 22nd 2013 – There is a related post no up Quantitative Analysis of Daylighting and Lighting directly from Revit

Tell us what you think: We are eager to get your feedback, your ideas for improving this feature with new workflows and capabilities, and to hear about how you can use this feature in your work today. So take a look and let us know what you think.

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