Added lights not showing in iray
garlicpepper
Posts: 6
in New Users
I'm having trouble adding lights and then rendering the scene in iray. A scene that uses sun light renders just fine. If I load a inside scene where the sun is blocked and add my own lights the scene renders black. The added lights show up in 3delight but when I try to render in iray it's as if the lights are not added. Any thoughts on what the problem could be?
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Comments
Iray is much like a digital camera, without automatic exposure adjustments. The default exposure is set up for the included HDRI in the environment...that means a bright, sunny day. When you move to an inside scene, everything is still set for that default.
So you can increase the amount of light put out by the lights, adjust the exposure (tone mapping) or both.
I've tried increasing the light to 1000% intensity. In the main window everything is very white. In iray preview and render, still black. Should I try increasing light even more?
Don't use intensity...
Luminence values (several different units can be used watts, lumens, cd/cm2, cd/m2, etc) are what you need to increase. As far as I can tell, the Intensity slider, in Photoreal mode, only increases the light in OpenGL viewport (the Iray preview is untouched).
Need more detail. Do not understand, you shared increased light to 1000%, is that in light tab ? Are you using DS default lights ? Are you selecting the light/primitive applying Iray emiissive, adjusting the luminance ? In render settings are you selecting dome and scene or scene only ? More details would help us assist.
I alway's begin with indoor lighting luminance at 100,000, some indoor lights can go up to 10000000, depending on area to illuminate. Once you are satisfied with lighting, you can use tone mapping to make adjustments.
Thanks for your help and replies. I've managed to set lights to work in my scene using spotlights, linear point lights, and point lights. Before I was using default distant lights, I can't get these to show no matter what I do. I've tried adjusting Lumen strength to about 15,000 and Film ISO to 100,000. This helped greatly except for distant lights, which don't show.
My question now is can I somehow move the sunlight origin indoors? I'm trying to illuminate a big lecture hall. If I render using dome and scene and remove the roof this adds a good amount of sun light to the scene. With the roof added all the sunlight is blocked and it seems like my only other option is adding 50 or so linear pointed lights? Thanks again.
Hopefully someone can assist with sunlight. I've rarely ever use sunlight, and never used for interior lighting. What prop are you trying to illuminate ? Prop should come with lighting props, to convert to emissive.
If your scene doesn't illustrate interior roof, then you can remove roof, c how that turns out. If roof is not in the scene, the way I would try is, convert the roof/ceiling to an emissive light.
Sometimes it's easier to start from scratch when trying to resolve something like this. By this I mean delete any lights you've created. Next, click the "defaults" button in the render settings to get you back to a baseline. Now, unless the lecture hall has windows, set your environment mode to "scene only" since there is no way for any light being generated outside the hall to get in. Next, create a spotlight and put it somewhere close to your camera. Make sure it's actually inside the hall, though.
By default, the spot light will be set to 1500 lumens which for a large space is pretty low. Crank that bad boy up to 50,000 or so and do a test render. Even with the default tone mapping, you should see something. If you do, then great, now you can add more spotlights throughout the lecture hall to get the lighting you want. You can also use point lights. I, personally, don't use the linear points because they don't necessarily follow the laws of physics, and I try to go for realism.
Also note that you may want to adjust the temperature of the lights since they'll default to 2900 which makes the light similar in color to typically incandescent lights. If you want it to be more like daylight, you can use 5000 to 5200. For more of a fluorescent type lighting, something something anywhere between 3000 up to 4200 or so will work. For spotlights, you can also play with the spread angle to get more coverage out of it. In addition, you can alter the geometry used for the spot light by changing it from a point to a disk or rectangle. If you do change the geometry, then you can adjust the height and width parameters as well which will have an effect on how hard or soft the shadows are for objects illuminated by that light.
If your hall has windows, and you're wanting something that replicates being lit by natural sunlight, make sure your windows are using an Iray glass shader (usually the thin glass one), and then you can use the Sun-Sky environment mode.
By illuminate I just meant add light to my indoor lecture hall. When you say lighting props do you mean the light fixtures in the scene that don't actually emit light by default? I turned the entire roof to emissive and that has succesfully added light to my room, thanks! I didn't know about the emmisive setting. Maybe I should just add emmisive to the lighting props like you suggested to get a more realistic look?
Both of these are good options and it totally depends on the look you are going for. Save the scene wit hteh emmisive roof and try adding the emmissive lighting to the props and see which you like best.