Lighting analysis?

[ariasdelcid]

Can revit do photometrically correct lighting analysis? Thank you in advance for your help.

[beegee]

Currently no.

Its in AR4 though. And its in Viz ( I think ) so ... in the future ?

[jwilhelm]

of course Accurender 3 has lighting analysis but to date that has not been incorporated into Revit

[gordons.68934]

Yes agree (radiosity = reflection bounce interpretation)

AccuRender also has the ability to do animated sun studies (very useful) which is not available in Revit! So I have to export 3D to autocad/accurender.

When can we expect AR4 in Revit?

An excerpt from the manual. Not sure id this means photometrically correct.

AccuRender uses radiosity, a powerful technique for calculating indirect lighting. When used properly in conjunction with raytracing, this technique can produce images with more subtle illumination and more accurate lighting than those produced using raytracing only. The results of the radiosity calculation can also be used to analyze the lighting in your model.

Advantages of using radiosity

Potentially better image quality for architectural interiors
More accurate distribution of light
Lighting analysis
Interactive walkthrough of the radiosity model
Faster raytracing
Less sensitive to the number of light sources in a model.



Steve.

[hand471037]

An excerpt from the manual. Not sure id this means photometrically correct.

It doesn't. Radosity is just where the computer can fake how light is bouncing around within the space. It really has nothing to do with correct and accurate lighting levels, glazing specs, surface behavor....

What 'photometrically correct' usally intails is the ability to use .iges files (which tell the computer exactly how a light fixture is really behaving) and proper Glazing specs (which tell the computer how the windows and glass are really behaving). This way you can 'trust' that the Rendering is really what it's going to look like, not just a pretty picture.

Revit currently can't do either of these things. Viz can do the first, but I don't know if it can do the second, but I bet it can somehow. Lighting Designer packages like Radiance were built for this kinda stuff.

[ariasdelcid]

thank you All... jwilhem lets do a Revit group... I was trynig to see if Revit could be used directly instead of Radiance or Lightscape...Question: Is Viz goint to replace Accurender?

[beegee]

...Question: Is Viz goint to replace Accurender?

There's been a lot of speculation about that, if you search the Forums you'll find plenty of reading.

If it does, it won't be soon.

[ariasdelcid]

Thanks BeeGee... I guess I will wait to see what happens...I hope that is a wishlist item...

[GuyR]

I was trynig to see if Revit could be used directly instead of Radiance or Lightscape.

Accurate digital Lighting analysis is bloody difficult. Studies such as the one below show that Radiance is arguably the leader of the pack. As Jeffrey will attest setting up Radiance is anything but a walk in the park. Given we haven't even got a reliable rendering solution in Revit yet, I can't see lighting analysis being a priority from the Factory unless enthusiasts like Jeffrey can get a decent link developed.

http://wwweng.murdoch.edu.au/FTPsite/LightSim.pdf

In summary:

"Perhaps the clear outcome from the results presented in this report is that the
RADIANCE package appears to be well positioned amongst all of the others, and
seems to be able to produce a consistent level of accuracy when compared to
theoretical, scale model and a selection of other simulation packages."

Guy

[hand471037]

I'm working on a way to get Revit models into Radiance automatically:

Currently, I have to Export to DWG -> Open in AutoCAD -> Re-Do layers and lights -> Export to Radiance. This isn't very efficent, for that third step bogs the process.

What I'm working on it Export to DXF -> Open in Blender using a plugin that leaves the Materials and Lights intact -> Feed Radiance directly (there are several plug-ins that link Blender & Radiance).

However, it's going slowly, for I'm finding Python much harder for some reason that Perl, Squeak, or shell scripting. Just haven't really gotten my head around it's syntax. Once I get something together I'm going to post it up as a formal project and link that to here, so y'all can check it out if you want...