Light aberration: not volumetric, not lens flare...

[Kelley]

As the last bit of the "Moving Foxhole" set, I'm building an alley where the action starts. I want it narrow and dark. So far, so good. But the lighting is giving me fits. I want a bright light at the far end so the characters throw long shadows in front of them as they walk forward. It's coming. But slowly. [ Biggest problem is that the right amount of light to produce the shadows makes a a burned-out, hot spot at the end of the alley]. But my biggest headache is the yellow rays indicated by the arrow. I searched Tools>Options> and there's no fog or volumetrics turned on. I looked in Properties under the light used in the alley: Volumetrics WAS turned on, now it's off, but the flare is still there. I checked the Camera in Properties and Lens Flare is turned off. Any thoughts on where this is coming from?[attachmentid=14124]

[robcat2075]

[ Biggest problem is that the right amount of light to produce the shadows makes a a burned-out, hot spot at the end of the alley

How about a kleig light? it's directional, it shouldn't make any hot spot at all on the wall behind it

[Kelley]

[ Biggest problem is that the right amount of light to produce the shadows makes a a burned-out, hot spot at the end of the alley

How about a kleig light? it's directional, it shouldn't make any hot spot at all on the wall behind it

 

I've got a Key Light installed, which indicates that it's directional. My solution to the hot spot, at the moment, is to move the back wall farther back. [an Ad Hoc solution until I get better control of the lighting].

 

But what about that flare? Where is it coming from? I think it's a function of the camera. It seems to move [a little] when I move the camera.

[KenH]

Hard to say without the project. It sounds like there might be still volumetrics/lens flare on the shortcut of the light....maybe.

What I'd do is simplify everything. Delete all the objects and see if the flare is still there. Then you know it's the light. Then go through all the settings. Try a kleig light and see if it's still there.

 

PS I'm not sure if volumetrics wouldn't look good...

[Kelley]

Hard to say without the project. It sounds like there might be still volumetrics/lens flare on the shortcut of the light....maybe.

What I'd do is simplify everything. Delete all the objects and see if the flare is still there. Then you know it's the light. Then go through all the settings. Try a kleig light and see if it's still there.

 

PS I'm not sure if volumetrics wouldn't look good...

 

Is a Key Light and a Klieg Light the same thing? The icon in the Choreography looks like it could be either.

 

I changed the light type to Bulb, and the flare went away. For the nonce, I'm not going to trifle with success. Gone is gone. As to whether it's the camera or the light, both are under suspicion.

 

I'm attaching a second pic. [the first in which this happened, tho'] In this pic. the camera is not looking directly into the light. [a Key Light] The light is behind a window grating. I took the frame, extruded it back three times and pinched off the last cell to make an enclosed box and then shone the light out the front. The results were not what I expected, tho' not unpleasing. I expected window pane shapes on the far wall and tiles. Will have to experiment further with with gels.

 

I thought about a light fog in the alleyway, but got hooked on the troopers casting long shadows down the alley as they walk toward the camera. I'm going to simply change the color of the far wall to something darker, and attach a very small, soft light to the front of each trooper for some facial detail.

[attachmentid=14140][attachmentid=14141]

[Stuart Rogers]

Is a Key Light and a Klieg Light the same thing?

No. A klieg is, in effect, a spotlight (as opposed to a bulb or sun). A key light is the light you use to illuminate the key part of your subject (for want of a better description), usually placed to illuminate the part of your subject that's facing the camera. Key lights are usually kliegs, but they don't have to be.

I changed the light type to Bulb, and the flare went away.

Your light was previously a klieg, and you almost certainly had the volumetrics setting switched on.

I'm going to .... and attach a very small, soft light to the front of each trooper for some facial detail.

Not a bad plan. Adding lights can increase render times and, in this case could have unpleasant side effects - if your trooper gets to close to a wall then the face light will illuminate the wall too. Not to worry - when you get to that point, ask us about "light lists".

[luckbat]

Ditto what Stuart said. Your shadowing needs are a perfect candidate for Light Lists.

[Kelley]

Not a bad plan. Adding lights can increase render times and, in this case could have unpleasant side effects - if your trooper gets to close to a wall then the face light will illuminate the wall too. Not to worry - when you get to that point, ask us about "light lists".

 

Thanks for the help, guys. I'll try to keep the troopers sober and walkin' straight ahead. [lol] There is one thing more puzzling me about this lighting problem. Looking at the diagram above the troopers, you can see where the light is positioned. [there is no roof above it.] Look at the picture and you can see how the light falls off. [it's a bulb, and should fall off equally in all directions, yes?] Why then, is the wall at the end of the alley so blindingly bright? It's sitting in a four-sided black box...about a half mile away. With another wall in front of it, also black, and a 50% transparency on it. Where's all that light coming from?

 

In the rendered picture, I've installed the small, soft lights at eye-brow height on each trooper. Shall I use 'light lists' to make these move along with the troopers? I was thinking of using a 'Translate To" Constraint with an offset. What do you think?

[attachmentid=14161][attachmentid=14162]

[Stuart Rogers]

Shall I use 'light lists' to make these move along with the troopers? I was thinking of using a 'Translate To" Constraint with an offset. What do you think?

You will need to use "Translate To" constraints as well as light lists. A light list is simply a way of excluding things from being illuminated by particular lights - it doesn't physically attach the light to an object.

[KenH]

Try adjusting the falloff or width of the light for the bright wall.

[Kelley]

In frustration, I switched the Bulb Light back to a Klieg...and, happily, whatever was causing the flare is gone on this light. On the other hand, my Klieg is not casting long shadows down the alley. It's right behind the two figures, [at about waist height] Intensity=333%, Cone Angle=66%, Fall Off=222', and Shadows is definitely turned ON, Darkness=100% I've tried upping [and decreasing] these values, but the long shadows just don't/won't happen.

 

Thanks for all the advice so far. I'll definitely be back when it's time for Light Lists![attachmentid=14182]

[KenH]

You mean the light is right at the end wall? Is there supposed to be a light source there? If you put something else in the scene, does it cast a shadow?

[Stuart Rogers]

Those troopers look like they're hovering. There are shadows on the ground directly under their feet. Or are these from different lights?

[Kelley]

Here' a diagram showing the alley, light & troops. [side View] The Kleig is enhanced a bit in Photoshop, but you can see the bedroll and bootheels of the tall guy, and where I duplicated a post and centered it in the alleyway. It throws no shadow. There's a small, rather weak Bulb Light above the two troopers. It throws enough light to show that, in fact, their feet are off the ground.

 

Stuart: I had been moving the troopers up and down the alley to check how the light was falling on them. At the far end of the alley, there's a set of stone steps. Step#1 is a bit higher than the floor of the alley.[attachmentid=14194]

[Stuart Rogers]

Here' a diagram showing the alley, light & troops. [side View] The Kleig ... throws no shadow. There's a small, rather weak Bulb Light above the two troopers. It throws enough light to show that, in fact, their feet are off the ground.

There's something about the klieg's shape that makes me want to ask if you can check the settings of that klieg and make sure it's fall-off distance is actually long enough to reach to the ground.

Stuart: I had been moving the troopers up and down the alley to check how the light was falling on them. At the far end of the alley, there's a set of stone steps. Step#1 is a bit higher than the floor of the alley.

Fair enough - I thought it prudent to ask in case we were missing that "D'oh!" moment.