Lighting dark/underground scenes?

olivercrosbiehiggs

I'm trying to do a scene set underground but when I try to render it all I get is a black screen because there isn't enough light, yet when I try to add spotlights they don't add any additional light. Does anyone know how to fix this? I will admit I haven't done many in door scenes yet.

Digital Lite Design

What product?  What render engine?  Is the spotlight outside a wall etc so it can't cast the light into the area?  You can select your spotlight in the Camera menu and "look" through it to make sure it is pointing where you need....  Can you give a bit more info?  Basically, to light something underground the light sources need to be inside that space - just like it would in real life.  You also need to set the Lumens high enough to cast enough light. (for Iray)  For example, a flashlight isn't going to illuminate a whole cave....  Can you add a screenshot of your scene setup?

mjc1016

First...is this an Iray render?

If so, what are the settings in Render Settings > Environment?

Also what does the 'set'/bacground/cave/dungeon consist of?

fixmypcmike

Assuming you're using Iray, make sure Render Settings > Environment > Environment Mode is set to Scene Only

olivercrosbiehiggs

Digital Lite Design said:

What product?  What render engine?  Is the spotlight outside a wall etc so it can't cast the light into the area?  You can select your spotlight in the Camera menu and "look" through it to make sure it is pointing where you need....  Can you give a bit more info?  Basically, to light something underground the light sources need to be inside that space - just like it would in real life.  You also need to set the Lumens high enough to cast enough light. (for Iray)  For example, a flashlight isn't going to illuminate a whole cave....  Can you add a screenshot of your scene setup?

 

Sorry, yes I am using Iray. The spotlight is placed behind the camera so it illumates the tunnel that the camera is looking down. I'm trying to create a dusty environment.

 

 

mjc1016

Add a couple of '0' to the Lumens setting....at least two (yep 150,000).

Ken OBanion

Another thing to try is to go into the 'Tone Mapping' group and start dinking around with some of those settings.

If you have any experience with photography (film or digital), you should recognize most of the parameters.  Typically, I dial down the shutter speed, ramp up the Film ISO value, and fiddle with the F Stop.  Lather, rinse, repeat as necessary....

In addition to everything else mentioned, of course.

SpottedKitty

Ken OBanion said:

Another thing to try is to go into the 'Tone Mapping' group and start dinking around with some of those settings.

This can't be emphasised enough, for complete newcomers to Iray rendering.

The "exposure" settings under Tone Mapping are the defaults for a bright sunny day outdoors, which is just what you get in the default Environment light. If your scene isn't bright, sunny or outdoors, but lit by "indoor" lights, then of course your scene is going to render completely black unless you dial up your scene lights to ridiculous levels. Look at the Tone Mapping settings as the controls for a manual camera, and adjust as necessary.

Ostadan

Is it the case that, as with photography, a ten-times-faster ISO (or equivalent tonemapping adjustments to shutter or aperture, in Iray's case) will lead to a noisier (or longer-to-converge) image than one with ten times the light flux?

 

Tobor

The tone mapping settings have no effect on "film grain" from a high ISO value, motion blur from a slow shutter, or depth of field from the f/stop. There are merely conveniences for setting an exposure value to use whatever light there is in the scene.

If the scene is dark, it is MUCH better to increase the amount of lighting, not rely on light emittance. Iray is a controlled environment, just like a photography studio. If you have the option to add more lights so you can maintain consistent tone mapping values, then why not? 

All the more, Iray renders based on the ray tracing in the scene, and the more light, the faster the render. As in real life, you don't increase the amount of light in a room simply by fiddling with your camera settings. The camera only responds to the result of whatever light that enters it.

As a BTW, the default settings are for a bright cloudy day, not bright sunny. For the last 50+ years, EV13 has been defined as bright, cloudy, but no distinct shadows. The setting for a bright sunny day would be f/16, and herein lies the Sunny 16 rule.

SpottedKitty

Tobor said:

As a BTW, the default settings are for a bright cloudy day, not bright sunny. For the last 50+ years, EV13 has been defined as bright, cloudy, but no distinct shadows. The setting for a bright sunny day would be f/16, and herein lies the Sunny 16 rule.

Ah, I didn't know that — I was looking at the default HDRI file, which seemes to have a clear sun in the sky with no obscuring clouds. And I've never really studied the nuts and bolts of photography, so I'd never heard of that EV13 definition.