IES ligths

[rhyzx]

I cant get these type of lights to work properly. The only way these lights work is if i increase the intensity/power to like 1.5 million then they work. I want to be able to use the intensity that comes preset with the file. how can i make these lights work ?

[fooprobe]

the tooltip on the brightness value will explain it. basically use a value of zero to use the file's intensity. if you specify any other number it will be in lumens. for reference a 100watt light bulb is something like 1600 lumens. so if you have the value set to 1.5 million that's like having a thousand 100watt bulbs. probably your camera exposure settings are way too dark. it's also possible your IES file is for a very dim lamp - where did you get it?

[rhyzx]

i understand that if i set the power to 0 the file's power settings take over but when i do that it doesn't work. this is what i do: open a new rhino file with default vray settings and vray materials , i create a new IES light then i assign a file to it, render, geometry is not illuminated by light. i dont mess around with anything else. this links to the IES files if you want to try them
https://www.dropbox.com/s/895say7iqr3v4yr/25.ies
https://www.dropbox.com/s/zknagp9mt4bxy5v/29.IES

[fooprobe]

these work fine for me with default everything, except of course i had to turn off the GI skylight to keep it from overexposing the scene:




here's my file:

IES TEST.zip

[rhyzx]

For some reasons i cant download your files " rhyzx, you do not have permission to access this page" even though im registered. anyways i think changing the model units has something to do with it. i normally model in feet/inches but when i switch the units to cm the ies lights somehow work. can you test that just to make sure?

[fooprobe]

you might talk to support about getting your permissions fixed.

my model is in inches, the wall was about 3' tall, lights were about 5" off the wall surface. try reconstructing my scene and see if it works for you.

when i change to cm (and click "yes" to scale the model by 2.54) i get the identical result. i tried changing scale to meters, feet, millimeters, always works fine, though sometimes i get IRMap glitches because of the scale. but the IES always works. (didn't work when i scaled to kilometers, but i suspect that's a tolerance problem - works with any normal units)

i did notice in the meantime that i had moved the ies files, and the lights remember explicit paths to the files, not relative paths like materials do. so maybe try reloading the files to see if that fixes it.

[tashko.zashev]

Hi Rhyzx,

The V-Ray IES light should produce same light intensity regardless of the scene units.
What is the exact VFR version that you are using?

About the "you do not have permission to access this page" message that you get, please send us an email to support@chaosgroup.com and we will assist you further.

[rhyzx]

im using 1.50.22564. im pretty certain the light intensity scales with model units. at microns is very bright, everything is white, and as i go higher the light gets weaker, and weaker. it may be a bad install or a glitch with the schools systems. to get them to work i just change the model units but say no to scaling, render, then change units back to feet/inches.

[fooprobe]

intensity definitely did not scale with brightness in my test. pm me with your email address and i'll send you the file.

[rhyzx]

Hey thanks for all your help. Ies lights just don't work properly for me too bad this is a school pc.

[tashko.zashev]

Can you post two example scenes with different units scale, so i can try them here?

[joe_b]

im using 1.50.22564. im pretty certain the light intensity scales with model units. at microns is very bright, everything is white, and as i go higher the light gets weaker, and weaker. it may be a bad install or a glitch with the schools systems. to get them to work i just change the model units but say no to scaling, render, then change units back to feet/inches.

Are you using the physical camera? The physical camera internally converts scene units to meters for its exposure calculations. If you are not actually scaling your scene then the physical camera is going to get very different results between 1 micron and 1 meter. Just imagine the difference of lighting a 25 watt light will have if your room is 50cm x 50cm versus 50m x 50m.

If you don't need physically correct renders / exposure you might want to just switch to our standard camera, units don't matter to it.

Hope that helps

[rhyzx]

It doesn't matter whether i use the physical camera or not. exposure is much when the physical camera is on though. here are some scenes plus ies file https://www.dropbox.com/s/9b1saskn86mk3ko/scenesies.zip

[joe_b]

Yes, you are right, you will still have the same issue regardless of the physical camera. This is because the IES light itself is a physically correct format. In your example scene your walls are ~195 scene units long, your light is approximately 45 scene units above the floor. So the same problem applies- a 25 watt light bulb is going to have a hugely different affect on a room 195 ft square vs a room 195mm square. A 25 watt light bulb suspended 45' from the floor is unlikely to yield much result, whereas a 25 watt light suspended 45mm will have an obvious affect. In your feet.3dm you are only getting indirect illumination from the environment. The IES light is falling off before it even reaches the floor.

It is best to have your scene setup in accurate units, if you must change scene scale you should actually scale your scene so that the overall dimensions are maintained.

[rhyzx]

In the "feet" scene did you try moving the light down ?