OTOY Forums

Hi SamuelAB,
you're right, octane converter has an error about light direction. I sent your developer issue.
About the different shape, I did some tests and they confirm my idea, the .fbx and vray slight shape using .ies does not change final render.
As you can see in my screenshot changing shape does not change anything.
Regards
Paride

Thanks for the update.

The lights do look different, but you have to have a sharp lighting design eye to tell the difference.

If you do a more drastic comparison with a longer thinner fixture, you can tell the difference, especially if the light is closer to a surface like a wall or floor. I don't have a valid Vray license (I use an expired trial to convert lights), but I can assure you that there is a major difference between point lights and rectangular lights.

Please confirm that you will also ask the developers to fix the area lights conversion. A point light conversion is not enough.
Thank you!

To test it out, make the light fixture 20 feet long and 1 foot to the ground. There is no way the point light will be similar in result.

Hi samuelAB,
there are two different lights: .IES light and shape lights, in this case you are using .IES lights.
shape light can be rectagle, disc, sphere etc, .IES light uses .ies file, shapes don't work with it.
you shared a scene with .IES lights not shape light.
I agree with your test, but it's not what you shared before.
Regards
Paride

Hi Paride,

I use the lights from Revit and these are 'shape light' equivalent in Revit. However, they are a combination of IES and shapes, as with any real light fixture.

By definition, a real light fixture must have a luminous opening shape, an IES profile and a lumen value. Anything else is basically a lie.

A few lights seem to convert properly into rectangles with IES lights, but most don't. What method do you suggest to be able to convert thousands of these lights into shape lights with IES properties?

Hi SamuelAB,
As you can see in my screenshot, using .ies file in VrayIES light or Octane IESLight, shape doesn't change your render.
your render will change but using a shape in Vraylight or OctaneLight.
Regards
Paride

Hi Paride,

Are you saying it is not possible to have both a shape and an IES file in a light? If so, then I would suggest making that possible as soon as possible since it is the basic recipe for a realistic light.

I thought it was possible to add an IES distribution to an Octane light with a shape. The Octane documentation on this has always been unclear, so I've never really dug into it too much.

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My next question will depend on the first question: If it is possible to have both, how do I convert my Revit lights to have both and be accurate? Right now it is only taking in the IES information, but not the shape of the luminous opening.

For context, these are the ceiling and lights we use in Revit. So it gets exported with shapes, lumen and IES shapes.

As you can imagine, we start with thousands of lights with specific shapes and IES files to do specific lighting effects. This is an extremely basic version where most lights are round down lights and rectangular troffers. Nothing special. As we get more special lighting, it gets more important that these properties get respected so that we can visualize what is actually happening.
Which is why I want to find a way to automatically convert these. It would not make sense to try to place thousands of light manually.

Hi samuelAB,
could you share (in pm if you want) a .fbx file with only all of your lights and celing lamps please?
Regards
Paride

Yes of course. Here is the original FBX export.

I usually convert to Vray and then to Octane. This is before either conversions.

Keep in mind that this is another person's project, so the lighting is a bit bland. I go pretty crazy with my lighting (wall washer, ceiling lights, etc).

Please let me know if you need anything else or have any questions. The original file is in Revit 2019, but I cannot share it.