photometric output with both up and down components

[Anonymous]

Has anyone got a good solution for modeling and rendering light fixtures using .ies files that have both an up and down light component to them? Most families out there seem to have the .ies file located just below the geometry for a fixture shining downward (and just above for uplight). Problem is, when the light shines both up and down, the geometry itself blocks the light from the photometric file from reaching surfaces on the opposite side. See attached images of two identical families using the same .ies file - the one difference being that I've deleted the geometry for the horizontal surfaces of the housing and lens that block the light from the .ies file.

I remember a time when rendering with some other software, that there was a setting to make certain geometry "not cast shadows", so light would pass right through the geometry of the object.

The only hack I can come up with would be to have a nested family to provide a second light source shining up, but that's not good if software other than Revit uses the info for lighting calculations or if it properly distributes the light ignoring the geometry of the light.

Thoughts? Is this one for the wishlist? Does 3DS or another rendering engine handle the light differently?

[L.Maas]

If the material blocks the light depends on the material settings. If materials have a transparency value then they will let light through

For example see light hereunder where I only hanged the material of the backside into a glass type material

[Anonymous]

Thanks, Louis, for the additional workaround. Unfortunately, this does not work for me in most cases, as the geometry of the light fixture will need to be visible, and the lens rendered with a glowing material that isn't transparent. I will look into material settings further to see if I can come up with one that does not distort the light output and still renders as an illuminated lens would.

[L.Maas · Accepted solution]

Depending on the material you can have different material settings.

For example a material we often use for diffusers. As you can see it has both self illuminance and transparency settings

So this material is visible, self illuminating and transparent. It is based on the "Glass, White, High Luminance" material form Autodesk materials

[Anonymous]

So can we turn on transparency so as not to occluded the ies file but have the luminaire geometry render as opaque ?

[Anonymous]

Hi, 

Please clarify if it is possible to turn on transparency so as not to occlude the ies file but have the luminaire geometry render as opaque.

I'm trying to create a Direct/Indirect suspended linear luminaire that looks like this:

The geometry is a simple cuboid. 6 rectangular faces. 2 different Revit materials; A  "glow" material for the horizontal faces and a grey material for everything else.  Note that the grey material for the sides of the luminaire is opaque and needs to render as such.  

The ies file looks like this.

Where should I position the ies file within my cuboid for it to render correctly? And what material settings for the two materials so as not to occlude the ies light output?

Thanks in advance for the clarification.

Kind regards,

Alex

[chris.morse]

"So can we turn on transparency so as not to occluded the ies file but have the luminaire geometry render as opaque?"

Simple question that we all need an answer to, as the ies file already accounts for fixture geometry.  If the answer is "no" at least we can stop struggling to find a solution.  Troubleshooting this, at least for me has wasted an embarrassing amount of time.