Converting photometric lighting to Corona lights

[samuelAB]

I am using 3ds Max to link a Revit file, so it provides me with up tp date photometric lights.

The Material and Light converter does not (seem to) convert Photometric lights to Corona lights and support has been touted for photometric lights. However, I am finding that linear or rectangular photometric lights do not emit in a linear fashion.



Would it be possible to fully quickly convert these to Corona Lights?

[racoonart]

I am not aware of any problem with photometric lights conversion. If you can provide me a scene (just a couple of lights which do not convert properly) and tell me what exactly is not working as expected (and how it should be), I will sure be able to help ;)

[Edit] Btw, the converter does not make CoronaLights out of photometric lights. It just changes the shadow type - so it will (or should) produce the exact same output as before.

[maru]

I think photometric lights are not fully supported by Corona (for example shape of lights) so this is an issue. I will check it.

[romullus]

Regarding the shape, it's how those photometric lights works in max unfortunately. I waited for years that Mental Images, Nvidia, Autodesk or whoever responsible for it, would fix that damn behaviour... but it just didn't happen.

[maru]

I am not sure if we are talking about the same thing, but here is a comparison between MR and Corona. The same light settings (only shadow type changed for Corona). For me the result of MR seems "expected" and Corona ignores the light shape and renders it as a point.

[racoonart]

mmhhh.. I see that there's a problem. What if you use a corona light instead? It won't use the "true" lightshape either, right?

[maru]

No, Corona light works perfectly normal. The only problem is Corona ignoring native photometric light's shape.
(in attachment it's Corona light)

[racoonart]

That's what I mean, you have to make your own. It's very different from using the native shape of the ies file.

[romullus]

Don't know if it's fixed in max 2015, but in previous versions photometrics renders like in my attachment. It's barrely noticable in cylindrical, but very obvious in rectangle or disc shapes.

Of course, tha way Corona renders photometrics is unusable, but hey, it has its own lights which works great. I think that being modern path tracing engine, Corona offers to much support for legacy stuff. Did you know that Corona proxy renders in Vray, MR and even scanline renderers, while MR and Vray proxies are recognized only in native engines.

[samuelAB]

Hi Deadclown,

I am looking for a converting solution. I work with Revit, so it imports my latest lighting designs into 3ds Max (150+ lights at a time). I would not be able to convert all the lights manually.

If Corona could read the geometry information of the photometric light shapes, that would work as well and save an extra step.

I've made a test file for you and discovered a few weird things. The Photometric rectangle seems to be divided is a 8x8 grid, my previous render must've been using a cylinder. The lights were all at 1500 lumen, but the Corona light rendered much brighter.

http://www.mediafire.com/download/2qq7cuf7z5ki2r5/CoronaLgihtTest.max



Regarding IES file shapes of photometric files, the sometimes use a code for shapes that is read by some photometric software (AGI32, etc). So some IES lights want to be rectangles or circles, not just points. Then again, the IES file format is know to be totally inadequate for near-field photometry. We'll need to move onto light-fields for true accuracy.

LM-74-05 is a good document to read if you're really going to dig into IES files. www.ies.org/store/product/standard-file-format-for-the-electronic-transfer-of-luminaire-component-data-1091.cfm

[Tzannes Luke]

Has there been any progress on this issue.
Our office also uses Revit for design and modelling. We put our lights in Revit but cant convert the photometric to corona lights in Max.
This would be a seriously helpful addition. Can it be incorporated into the conversion script.

[maru]

We will have to revisit this. Stay tuned...