[Frances]

Since it's been determined that units are correctly interpreted by the Rhinoll camera, I converted a job I'm modeling back from meters to inches. I had already started a render while still in meters and I let it continue. So, once I converted back to inches and repositioned my camera, the only change to the camera was the lens length to 50mm. In the "meters" render, it's at 24mm (I had zoomed in from a wider shot and since there are no clipping planes, the wide angle). Could lens length affect light intensity? I don't have time to do tests. In fact, I shouldn't even be here right now. But I thought I would share this finding and ask questions.



Physical sky and sunlight
fStop 5.6
Shutterspeed 100
render time 4 hours each
meters render reached 16 samples
inches render reached 17 samples

Not sure if the extra sample achieved by the inches render would account for noticeable increase in brightness, but I doubt it.

[Thomas An.]

Did you change your bounces by any chance ?

[Frances]

Did you change your bounces by any chance ?

No.

[Thomas An.]

Sorry for asking the obvious about bounces..

Now, I am trying to replicate this exposure change, but so far I have no luck after doing a number of quick tests (halving the lens length). I will give it some more thought.

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[iker]

Yes, I think thats normal, emitters has decay rate, it works like if you put a light close to an object and render and then you put the same light far away

[Frances]

Sorry for asking the obvious about bounces..

Now, I am trying to replicate this exposure change, but so far I have no luck after doing a number of quick tests (halving the lens length). I will give it some more thought.

-

It could depend on the dimensions of the space whether the intensity is more or less noticeable. This particular model is ~32'Lx24'Wx22'H (9.75mLx7.32mWx6.71mH if I did the calcs right).

I guess the question is - which one is right?

[Frances]

Yes, I think thats normal, emitters has decay rate, it works like if you put a light close to an object and render and then you put the same light far away

I don't think this is normal. No matter what ruler you measure a space with, it's the same size. The size of the space has not changed, only the unit of measure and the lens length.

[iker]

I don't think this is normal. No matter what ruler you measure a space with, it's the same size. The size of the space has not changed, only the unit of measure and the lens length.

I don't know exactly what you mean but I think if you have a 100W light is not enough to illuminate 2 km2, but it is enough to illuminate 2 m2.

[Frances]

I don't think this is normal. No matter what ruler you measure a space with, it's the same size. The size of the space has not changed, only the unit of measure and the lens length.

I don't know exactly what you mean but I think if you have a 100W light is not enough to illuminate 2 km2, but it is enough to illuminate 2 m2.

Can you understand the difference between size and units of measure? The SIZE of the space has not changed. ONLY THE UNITS OF MEASURE. When someone measures you, are you taller when they measure you in centimeters or inches?

Here is a test. Everything is the same except for the units of measure.

[Thomas An.]

Frances, I haven't done tests with indirect illumination (all my earlier tests were outdoors).

In your latest test, it would be interesting to see what happens if you change the unit to microns (so your space will be a few billion microns wide).

If anything is glitching it should become more evident. I will try a test too (but I got to find some time first).

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[tom]

while reading these posts i started to think there must be a bug in the lighting system if what you say is true...
if the lighting changes when you just change the units (not the scale), then there's something wrong i agree.

[iker]

Can you understand the difference between size and units of measure? The SIZE of the space has not changed. ONLY THE UNITS OF MEASURE. When someone measures you, are you taller when they measure you in centimeters or inches?

I understand perfectly the difference ( what I can't understand is because my english is not as good as I'd like ).
What I was trying to say was that maybe someone has convert units without scaling , and if you have a emitter acting as the sun , it affects the whole scene illumination because the size and the power/intensity of the emitter (I thought that was your problem)

btw/ I think I'm taller in cms!....182 - 1.82...............182 sounds better!

Once again, sorry for my english

[lebbeus]

what if this is just a problem due to the interperlation of the maxwell information into the image file? Since your effective view of the scene is different with the 50mm lens than the 25mm lens wouldn't the perceived lighting also change? The actual lighting isn't changing, just the part of the scene that is actually seen by the camera/eye which could effect the perceived contrast of the scene. ???

[Frances]

In this test the lens lengths are the same in both scenes.

[Thomas An.]

Hi everyone,

I had a little time to do a test on this.

Created an indoor scenario of an L-shaped room. The room was modeled in feet and then the unit system was changed and rendered to microns, centimeters and miles. In all three scenarios the dimensions of the room were equivalent (30ft =9144000microns=0.005681818miles)

Color samples were taken at three locations (on each image) and their RGB values were recorded and found to be identical