Accurate lighting with IES profiles?

[alexengelmann]

I'm trying to figure out how to use IES profiles in Maya to get somewhat accurate lighting in a scene. We are updating one of the rooms in the office here and I was going to model out the changes to see how they look before we proceed. I want to make sure my lighting is somewhat accurate, so when we install the lights it looks close to the render.

 

I've think i've got the process down on how to use the IES profiles and mia_photometric_light. Here is an example of a quick test i whipped up:

 

The room is a 10'x10' cube. I'm using THIS IES profile. And have it attached to an 8" disc area light. I have a mia_photometric_light shader attached to both the Light Shader and Photon Emitter slots of the area light. I also have a mia_exposure_photographic shader attached to my camera. Here are the settings for those shaders:

 

 

The material on the geometry is a mia_material_X_passes. I'm using the Matte_finish preset with a 90% white color in the diffuse (with a gamma node set to .455).

 

My concern is how accurate can I expect this lighting to be? Which is closer to reality, just GI, or GI+FG?

 

If I were to model out the new design and light it with the IES profiles of the lights we want to buy, can I expect the render to be in the same ballpark as the real thing?

 

Lastly, in case it might help. You can download the test file and IES profile HERE

 

Any help or resources on the matter would be very helpful. Thanks!

[Ismael]

Download Dialux and calculate the light distribution...

I used 80% ceiling reflectance, 60% walls and 40% floor...

Results are such as this:

 

 

 

I have a light meter, an Extech Light Meter and I could go and measure similar levels and 'see' what that illumination looks like.

Then I render it. In my Vray rendering setup I used ISO=100, F=8, SS=1 which is an EV that translates to about 15 foot candles.

This is what I get:

 

 

 

Maya? I have no idea but with Dialux, a light meter or Camera... You can get a good idea what your space should look like.

 

I think...