Lighting consistency across series scenes?

RenderPretender

Hi -

For those of you who do image series that occur in the same setting, such as in a studio, I'm wondering how you achieve lighting consistency. I try to use only the same lights and settings throughout, yet even with Iray lighting, and all else being equal,some panels just don't seem to "belong". Anyone else perceive this issue, and how do you approach it?

Herald of Fire

Tough question to answer, because lighting can depend on a variety of things. Keeping the same light setup is great, but only if you also keep the same angle. If you're lighting a scene from the front and then have a shot from the side, you might see darker areas which could break the illusion.

You can add extra lights such as 'ghost' lights to add filler which may help brighten it up a bit, but it all depends on what sort of scenes you're rendering. Have you got any examples of inconsistent lighting you can share?

RenderPretender

Herald of Fire said:

Tough question to answer, because lighting can depend on a variety of things. Keeping the same light setup is great, but only if you also keep the same angle. If you're lighting a scene from the front and then have a shot from the side, you might see darker areas which could break the illusion.

You can add extra lights such as 'ghost' lights to add filler which may help brighten it up a bit, but it all depends on what sort of scenes you're rendering. Have you got any examples of inconsistent lighting you can share?

What I'm trying to do is stay with the same number and type of lights within a series. Normally I select all the lights and make a group so that I can rotate them all at once around the subject, while maintaing the lights' relative position to one another. It's not perfect, but it's the best solution I have found. Three lights is generally a max, plus a ghost light for indoor scenes, because of the risk of unwanted backlighting by an intended sidelight.

Herald of Fire

If you're rotating the lights with the camera, you run into another problem and that could be the reason for your inconsistency. If a shadow is being cast in a particular direction in one scene, you'd expect it to be cast in the same direction in the next, unless the lights themselves are visibly moving (swinging lantern, for example). If you're moving the entire rig, it may be bright enough to see everything, but it's not the same lighting because you're doing the virtual equivalent of moving the sunlight.

If you want a full scene, the best option is to simply make sure that you've got a well lit area to begin with and leave the lighting well alone, save perhaps for a weak ghost light for filler. That way you can move the camera through the scene without it having a huge impact on the visuals.

Ostadan

Even Hollywood movies don't always get this right.

RenderPretender

Herald of Fire said:

If you're rotating the lights with the camera, you run into another problem and that could be the reason for your inconsistency. If a shadow is being cast in a particular direction in one scene, you'd expect it to be cast in the same direction in the next, unless the lights themselves are visibly moving (swinging lantern, for example). If you're moving the entire rig, it may be bright enough to see everything, but it's not the same lighting because you're doing the virtual equivalent of moving the sunlight.

If you want a full scene, the best option is to simply make sure that you've got a well lit area to begin with and leave the lighting well alone, save perhaps for a weak ghost light for filler. That way you can move the camera through the scene without it having a huge impact on the visuals.

I think your second paragraph is actually the key, which would mean using enough key lights to light everything uniformly and light the character from any camera. But then you have unintended backlighting I'd guess, as well as multiple shadows. So, how do you achieve a suitably well lit area? It's a quandry.

thebiggydiggy

Not sure how much work you want to put in and what characters are in your scene, but I struggled with this for ages and believe I've managed pretty ok. Lighting the area and leaving it alone works sometimes, IF you know ahead of time where every shot will take place. If not, I guarantee some character is going to have several different skintones or alternatively a complete absence of shadowcasting and looking like a ghost. I wanted uniform lighting in any area, from any angle, with any number of characters, without that bleak gamma corrected look/complete absence of shadows due to overlit areas. I ended up mass-compositing beauty passes in photoshop, or very rarely lightroom in photoshop isn't managing.

The scene USUALLY works just fine with a simple roof removal and appropriately tilted HDRI. If the ceiling/roof is in view I composite it in afterwards. Walls need some looking out for because a roofless wall will cast a nasty shadow depending on the contrast of your HDRI and the tilt. I'll manually remove geometry from scene to scene if it gets in the way.

The characters aren't in the scene at all. After the scene is rendered I disable the area, placing just the characters. Usually individually but sometimes multiple at a time is less hassle. I'll iray matte anything the character casts heavy shadows on, then I render out whatever number of passes I consider appropriate, using whatever rotation/tilt of the HDRI (or multiple HDRIs which you can composite with linear dodge) I consder appropriate. These renders take almost no time at all and leave you with several .exr files that contain such a stupendous amount of data (and still only a fraction of 32bit) you can make the character look however you want with exposure/gamma/saturation/etc adjustments. I'll repeat this for however many characters I want in my scene.

RenderPretender

thebiggydiggy said:

Not sure how much work you want to put in and what characters are in your scene, but I struggled with this for ages and believe I've managed pretty ok. Lighting the area and leaving it alone works sometimes, IF you know ahead of time where every shot will take place. If not, I guarantee some character is going to have several different skintones or alternatively a complete absence of shadowcasting and looking like a ghost. I wanted uniform lighting in any area, from any angle, with any number of characters, without that bleak gamma corrected look/complete absence of shadows due to overlit areas. I ended up mass-compositing beauty passes in photoshop, or very rarely lightroom in photoshop isn't managing.

The scene USUALLY works just fine with a simple roof removal and appropriately tilted HDRI. If the ceiling/roof is in view I composite it in afterwards. Walls need some looking out for because a roofless wall will cast a nasty shadow depending on the contrast of your HDRI and the tilt. I'll manually remove geometry from scene to scene if it gets in the way.

The characters aren't in the scene at all. After the scene is rendered I disable the area, placing just the characters. Usually individually but sometimes multiple at a time is less hassle. I'll iray matte anything the character casts heavy shadows on, then I render out whatever number of passes I consider appropriate, using whatever rotation/tilt of the HDRI (or multiple HDRIs which you can composite with linear dodge) I consder appropriate. These renders take almost no time at all and leave you with several .exr files that contain such a stupendous amount of data (and still only a fraction of 32bit) you can make the character look however you want with exposure/gamma/saturation/etc adjustments. I'll repeat this for however many characters I want in my scene.

I really appreciate that detailed reply and recommendation, but that would be cost prohibitive in terms of time for a set of more than a couple panels. Also, you're way ahead of me on the learning curve. Most of my work is "studio" type, so it's not the end of the world if I have to parent lights to rig and rotate it directionally to get flattering lighting consistently across a series. I think I'm kind of stuck with that option, frankly.

ArkadySkies

One trick I've learned: you can use the camera's default light as a weak fill light. I use 3DL with gamma correction 2.2, but I got this idea from an Iray user (can't remember who). For iray, the ideal range for intensity might be different.

Under Camera Settings -> Headlamp, I lower the intensity to between 0.10-0.20 and adjust the other scene lighting (if necessary) and Headlamp Mode from Auto to On. From there you can use Edit -> Duplicate to duplicate the camera and then move it if you are producing this series with multiple cameras instead of moving one camera.

RenderPretender

ArkadySkies said:

One trick I've learned: you can use the camera's default light as a weak fill light. I use 3DL with gamma correction 2.2, but I got this idea from an Iray user (can't remember who). For iray, the ideal range for intensity might be different.

Under Camera Settings -> Headlamp, I lower the intensity to between 0.10-0.20 and adjust the other scene lighting (if necessary) and Headlamp Mode from Auto to On. From there you can use Edit -> Duplicate to duplicate the camera and then move it if you are producing this series with multiple cameras instead of moving one camera.

That's a good idea. Usually, you have the camera light off with Iray, though, so it would have to be a weak light.

I'm considering trying to light indoor scenes with a strong enough overhead (or horizontal for window light) ghost light to light the whole room sufficiently, and use no other lights at all. The idea would be to emulate light coming from ceiling lights or wondows, thereby eliminating the need for directional lights... hopefully.

RenderPretender

This is a screencap of a test render (I stopped it at about 12 minutes) of a night scene in a gym. The only light is one 800k overhead/vertical ghost light that's X/Z scaled to span the area of the gym. Light would be coming from overhead florescents. Illumination seems to be uniform from all cameras, and I imagine at anywhere in the scene, though the character is now centered. It might even be able to tolerate a little less intensity, and still eliminate a lot of directionality problems... as long as the light is bouncing around the room as real ambient light would do. Using ghost lights only might be the answer for indor scenes, though it's hard to know when to use horizontal ones unless there are daytime windows, etc..

https://www.daz3d.com/gallery/#images/575941/

RenderPretender

I'm finding that a ceiling ghost light may be the ideal solution for my indoor lighting problems as a result of trying to achieve consistent lighting across image sets using directional lights. But the character can look a bit flat/matte because the ghost lighting is actually so uniform. Is there a way to reduce the matte appearance of the character without adding directional light? It seems like I need more specular feedback or something.

nicstt

Lighting is consistent; meaning as an example 1 x 100W light.

What is not: is how many walls, their covering/surface (same for floor and ceiling); camera angles; objects in the scene that both add to reflections, and block light; size of the enclosure the light is in; if there are places the light can escape, or other light can enter.