Renders get darker the further the camera is from my emissive light source?
Paradigm
Posts: 423
in The Commons
Hi all,
Another question on iray lighting. I have panels shining light into a house from outside. If I render outside looking it it's fine and well lit (close to the plane), but the further I move the camera into the house (further from the light source) the darker it gets, to the point where it's an almost instant render of pitch black. These are areas I can see are well lit from my outside render.
This doesn't make much sense to me.
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The only thing I can think of is fall off...there's just not enough of a light level to overcome the falloff.
Why would that affect the amount of light in the room when I adjust the camera? Forgive me, I dont know much about photorealistic lights.
I had this problem on a completely enclosed scene with just sun sky setting looking up the properties of real glass seems only 8% of light is reflected assuming a perpendicular direction and a refractive index of 1.54 which come out to be about .28 on the reflection surface node and much more light will enter versus being relected away from the camera, http://glassproperties.com/reflection/ try and see if that helps most glass shader put the reflection at .5
The more distant from the source, the lower the level...let's say at 2 meters, the amount of light is 1/4 as much as it is at the source...at 4 meters it's 1/16th as much. The inverse square law applies.
But that's only one possible contributing factor....thinking a bit more about it...the glass properties could be having a major effect, too.
And for things like this, is the Architectural Sampler turned ON? It may help in this case.
After a few quick tests...yes, I am seeing it now. But only in certain cases.
Namely if the size and placement of the emission planes is such that the movement into/through the room passes over a distance doubling. In other words, if the planes are 1 meter outside the room and the room is 4 meters wide, by the time you get to the other side you've lost a lot of your light.
But if the planes are 10 meters away from the 'outside' and the room is still 4 meters wide, it's much less noticeable. Moving them further away lowers the effect even more. Of course, you'll need to up the initial light levels, at the greater distance.