, by Lionel Koretzky

Capturing Light for 3D: a Photographer’s Journey in IBL Production

Lionel Koretzky details how his team produced thousands of photos that would become the new Substance procedural lights.

  • Architecture
  • Design
  • E-Commerce
  • Fashion
  • Film
  • Game
  • Technology
  • Transportation

Today, you can access 70+ environment stages on the Substance 3D asset platform. These 3D light environments were produced by Lionel Koretzky and his team, working in close contact with the Substance team. Lionel, who is an expert photographer with remarkable mastery of light (judge for yourself in his exceptional portfolio), explains the months of production required — from the concept to the photoshoots.


Lighting is everything. It sets the mood, the aesthetic of the image. You can frame to perfection or have the strongest subject: if the light is not right, the photograph will be average. 

Light is magic. It happens. Just as your scene is set to the millimeter and exposed to tenths of a stop. As you’re setting it up, you move a spotlight across the studio and you say, “Stop! Here!” You just saw something special happen. 

Or it could happen as you turn a street corner and see the light bounce into a building, onto the sidewalk, and there’s that moment again: “Stop!” Beautiful. This is the essence of photography.

Concept and setup

From photography to virtual photography

Capturing light, an ever changing element, freezing it in time: it’s the very power of our medium and if it’s done well, it can touch anyone. 

Capturing lighting designs in 3D lights, otherwise called IBLs (image-based lighting), framing into them, and eventually making the whole stage available and customizable to and by CGI artistsb is an amazing opportunity to contribute to photographic innovation. It is also an amazing journey, and quite the creative process. 

Working on this project with the Substance team gave me the chance to advocate for more realistic and beautiful lighting tools for CGI productions.

I was asked once to light a watch in a rendering software tool for a renowned luxury brand. To do that, I had to create an IBL. I produced a good lighting environment for it and a good final image. The client was happy, but it never looked real enough to me. 

The thing is, there is such a thing as too perfect. Watches, like cars, are “mirrors,” with three-dimensional angles in which you see everything. The reflections were too clean, and gradients were too linear; hot spots needed to be in the middle of their lighting area and fade in a perfect circle. 

I believe what we strive to do here is to bring the element of reality back to these reflections, spots, and hotspots. A gradient won’t be the same twice — because we move the light behind a diffusion or plexiglass, and because it hits that diffusion at a different angle and distance each time; because we use specific lighting for specific scenarios, and so on. We always work toward perfection, we prep precise set-ups, but nothing is permanent: the space in which we work is different, or the diffusion frame we ordered that day is different, or the weather acts up. 

One of the biggest challenges of IBL production is creating a lighting design that can work and be beautiful at different angles: from the front, back, side, and maybe the top — always having in sight the exact place where the IBL is captured. Having done commercial videos might have helped me here. It’s definitely a great exercise. And we did take some pretty cool pictures.

The other challenge is to keep spontaneity in the work, to fuel creativity over time, like in more traditional photography. And this isn’t easy, especially since taking these pictures can take hours at a time.

The production brief

We started by building a matrix around different types of lighting and their possible applications. 

The team came up with a couple of different types of lighting setups that we could repeat in different environments, studios, or locations. As we produced more content we gained experience, which would allow us to complete the setups with more types of lighting and/or more environments. 

But at the very beginning, our designs needed to be broad and commercial

I came up with a soft setup, a harder one and something inbetween, both for product images and people or fashion. It sounds very general, basic – soft, hard, and medium – but this setup is the best to match so many subjects and speak to so many eyes. After all, we have these 3 basics stuck in our brain, only with slightly different names, when we think about our environment: it’s overcast, sunny, or lit. 

Pre-production: kilometers of black and white tape

A campaign always starts with a pre-production meeting. We determine the theme, industry, or specific lights we want to work with.

Following that initial meeting, I usually take a couple days for creative research. I draw setups and make a keynote presentation of the different lighting designs with examples from my portfolio. If it’s on location, we’ll also work on a virtual scouting and propose possible options. 

We meet again and agree to do this and that. These meetings are usually very straightforward and productive: every option is reviewed and decisions are made to go to the next step, each time. It’s a real pleasure. 

Once our plan is ready, the campaign is on the move. I build budgets, book people and places. We make equipment lists, we do a proper location scout if needed, address technical issues, test lights, and above all, we make sure our gaffer tape stock is overloaded. Because making these IBLs and environment stages takes kilometers of black and white tape (and quite a bit of fabric, too).

Tape and fabric is essential indeed: on set, we hide everything that must not be seen! We have to prevent reflections. Otherwise, anything can flare into the lens capturing the IBL or inside a diffusion frame, like stands or brightly colored stickers with vendor names. Every single bit needs to be masked, especially since there’s no real retouching of the IBL image. 

Production step one: understanding how the light moves

The usual shoot takes 4 to 5 days in a row. The first day is dedicated to pre-light, where we take control of the space. If there’s daylight available, we have a full day cycle to understand how light moves around in the morning versus the afternoon. We get enough time to watch how the sun might bounce into a building across the street between 2 and 4pm, that sort of thing. 

It’s also a day we use to build frames, black out solid walls, organize the set, test lights, look at it all through a lens — and for me to verify that the plan I had on paper works: that I’ll be able to take pictures in the setups I designed from the different angles I envisioned.

If everything goes to plan, we end the pre-light day with a first IBL test of the first set-up. The next morning, we are ready to capture a complete environment stage. 

Production step two: Capture

A complete capture, without having to set up or change anything, takes 4 to 5 hours. Setting up a new stage is about the same, so this all comes together as fairly long days. We ran over time on many occasions. 

What I produce during these photoshoots is packages. Inside you’ll find an IBL (360° picture that includes light data), 3 to 8 backplates which are retouched, and “single lights” — straightforward pictures of each light source (soft boxes, diffusion frames, or windows) that plays in the setup.

Image-based lighting

We shoot IBLs in 8K. IBLs are made of a range of 18 exposures of each lighting source of a particular set-up.

Backstages

After that, it’s time to shoot backplates in 16 bits with a 60MP full frame 35mm sensor camera. I use a reference object — or a person, my assistant Symphonie, when it’s about lighting people — from different angles, through different lenses, all with a 35mm camera.

It’s just like a regular photoshoot. 

Except I remove the subject and shoot an “empty” frame. 

I shoot maybe 2 or 3 different light combinations, then a color checker with chrome and grey spheres for calibration. After this, I shoot a cube with markers, then we measure the distance and height of the camera — this will be used later to simulate the camera position in the environment stages. 

We also measure color temperatures, and exposure values of the lights. Sometimes, we also need to shoot some plates for post-production purposes.

We are very thorough. Diffusions are perfectly straightened, seamlessly taped. Poly-boards are new or re-painted on their black side. We bring together the electric lines, and lay them in clean paths through the studio. There are forests of flags to hide sources that shouldn’t play directly in the IBLs. All in all, these are very precise setups. They look good. Once again, we capture in 360°.

For each light design, we light up and shoot a reference object. For this, I used the speaker prototype the Substance team 3D printed. I made two versions: one painted in chrome, with the base in black lacquer, the second in medium matte grey with a matte white base. 

We set the light with both test objects on set, which allows us to test the IBLs on the same design in both Sampler and Stager. It’s very handy and has helped us anticipate and judge our lightings as we build sets.

We try to shoot two environment stages per day, but I believe we average 1.5 only. It’s a long process on set: all the elements needed for a full environment stage are equivalent to 8 to 12 shots per day on a regular shoot, and that’s about what clients usually ask photographers to produce. It makes me think we’re a tight production.

Matrix and results

We began studio work on October 5, 2020, in controlled environments for “packshots” with white and dark backgrounds. 

Then we shot in a loft-like studio, then a typical Haussmanian apartment-like studio, and then a more industrial one. We experimented with mixing in daylight on some of these occasions. 

Our base was solid enough that we decided to build on top of it. We added specific setups for cosmetics, for daylight, and another bunch for portraits and characters, all in a studio environment. 
With these covered and days getting longer as spring arrived, we decided to go out on location and we dragged our gear outside in May 2021.

Fake soft day light (FSDL)

This was the first setup I produced. As a still-life photographer, I work 80% of the time with daylight. I used to work in a studio in Brooklyn where I had great indirect northern day light, which I would contrast with black solids (sides, top) and white poly boards. 

To build this lighting, you work backwards, cutting into it, bouncing it, shaping a broad single source. It’s the most beautiful light to me. 

But this kind of setup won’t work every time. When shooting watches for clients, for example, I came up with a similar look with artificial lights (usually strobes). Watches or jewellery take time and there is a lot to shoot in a day, so you can’t afford to depend on the changing weather of the short winter days. 

Shooting our IBLs had similar requirements, so I started with the setup I used when shooting products with strobes. However, we had to switch to continuous lights so we could bracket 18 stops on the exposure time only (the 360° camera has only 3 stops in aperture and strobes wouldn’t go low enough in power). 

After a first test with a metal-halide lamp (HMI), we decided to go for a tungsten lamp on the rest of our studio production. Exposing our lights separately requires us to turn on and off sources many timesb and HMI just can’t be clicked on and off, since it needs to warm up and thus requires patience. Tungsten lights were much easier to deal with in that regard — and have the non-negligible advantage of costing a lot less to rent.

Fake Soft Day Light consist of a diffusion frame with white diffusion or silks of 1/2 or 1 full stop, and a Fresnel source through it. It usually goes straight into it, but is often offset to the top left or right of the frame. The idea is to recreate the feeling of the sun hitting through clouds. This is the key light. 

Then, we’ll have a fill light in the form of a soft box, maybe through a diffusion frame as well. It’s something much less intentional; there’s no real direction in the light, no shadow. The idea behind this setup is to open the shadows created by the key light. It will also fill the reflective parts of a product with a gradient instead of an underexposed wall, or a simple black solid set in the studio. It must not “cross” or “counter” the key light: it’s about accompanying it, making it “turn” around the subject. 

Finally, we can add a top light — a soft box or a hard source — bounced in the ceiling. Backgrounds are also lit as needed, in many different ways, depending on the creative brief; they’re always quite far from the subject so that they do not influence it.

The scale is pretty big. Although I started from a setup I used on small objects like watches, handbags, or jewelery, I couldn’t be too close to the 360° camera so that the lighting element wouldn’t “wrap” the subject too much when put into an IBL. It also helps its usability on different-sized objects. 

So, from a set that would usually consist of 4x4ft diffusion frames, soft boxes and table tops, we ended up with 8x8ft frames, 6x6ft table tops, 11ft wide backgrounds, and so on. Basically, much bigger sets and studios than those we usually work with as still-life photographers.

For fashion and people, we used a large 2.2m diameter umbrella — sometimes 1.4m, depending on whether the space available was smaller — with either 1/3 or 2/3 diffusion, facing the subject. The light inside is not aimed at the inside of the umbrella as it normally would be: it’s in the shape of a tube and hits it from all sides while pointing at its opened side. This tends to be similar to the “sun through clouds” effect of the product set-up.

Fake hard sun light (FHSL)

Fake Hard Sun Light consists of a Fresnel source, often 2 but preferably 5KW so that its lens is not too small, directly aimed at the subject like the sun would be. 

I usually diffuse it slightly with a 1/4 Hampshire Frost filter, just for it not to be too raw or directly on the source. This might require 2 fill lights: one similar to the FSDL, on the opposite side of the key light to open shadows and fill reflective parts, and another one very close to it, or right under it, to “soften” it without breaking the hardness of it. 

It’s been very cool to do, and quite different from what I usually do, but I’ve been inspired by my love of direct sunlight, which I use a lot and know how to treat in real outdoor conditions. The fact that it’s sharp in its direction and intention makes it react very differently from different point of views; it’s a pleasure to see it happen in the lens. 

I was very happy with the result in studio and had lots of fun applying it on location shoots, like the kitchen where we shot. We use fake hard sun light the same way for both products and fashion/people.

Hard Umbrella

This light is a sort of in-between, inspired by studio fashion shoots I did with my wife Saloi Jeddi (we used to shoot as a duo when we first met, and still do occasionally). It gives a strong direction to the light while having shadows that are not too sharp, and it looks good when backlit as well. It’s something we use a lot with strobes when shooting fashion. I used to use a small size umbrella for this, that an assistant would hand-hold and move around as we shot. 

There is nothing similar to tungsten lights, so we had to figure out something else. We used both white beauty dishes through a diffusion frame and octagonal soft boxes, diffused as well but at a small distance, not straight onto the box. We have a fill light for this set-up as well, but not so much on the opposite side, more often at the front, in the camera direction, and quite low. The point is to accompany the falloff of the light as we set up the key quite high on this. We might lose a full stop between where the light hits in a “sweet spot” and the feet of a model, for example. The fill then helps open and reed the bottom part of the subject, but again, without countering the key light. It should feel like it’s not there. 

Natural light

Finally we shot with daylight. We did a shoot at studio Astre and 3 other shoots on locations — a kitchen and a gallery — where we used the windows and available light, while still adding our own artificial lights to the design. Shooting with natural light has been very inspiring and generated a great deal of satisfaction. But it didn’t come easily!

There’s an immutable fact we must work with: natural light moves and changes throughout the day. It’s a mix of geography and meteorology, which suddenly turns it into a different practice. It’s really the notion of “happening” that I mentioned earlier: you want to catch that moment. 

And capturing these environment stages is a long process, remember, so getting the right result is a complicated equation. 

We did it, and we were impressed at how adaptable our setups had become. We made strong choices on the spot and reworked schedules quickly to match the weather changes. Still, it was a long process — but by then, our machine had become tighter, simpler, a bit smaller too, so we could be more mobile. 

I have to say that it’s lucky that the Substance team had us produce so much at the beginning in a relatively short period of time: it gave us the chance to learn to adjust our setup every time. So, in the end, when we got to these even more complex setups, we were able to cope and adapt.

We spent entire afternoons waiting for the right amount of clouds in the sky, or none. 

You’re exposing one run of bracket on the 360° camera and then the sun bouncing in the building outside shades over. You have to wait for the clouds to clear and then expose the next round. And you have to do that again if anything moves between brackets. 

We have Symphonie outside, on the street to see further out, telling us over the phone where the next opening in the sky is, and how long she thinks it will last. It’s a guesstimate. It changes, again and again. But eventually, we get the full bracket with a light that looks consistent to us. 

Sometimes, we didn’t get the light. Once, in despair, I decided to throw one of our strongest artificial lights that day onto the building outside. It wasn’t a lot of light but as the day advanced and daylight darkened a bit, it started to look good. The contrast became right, I made it warmer in color than the rest of the set and it popped. We ended up with something unexpected but really beautiful. 

We didn’t have enough time: the night was coming down quick. Symphonie called for killing the day and coming back at dawn the next day. We’d wait for the same balance as the sun would come up and start stabilizing, and we’d expose it all at once before 10:00am. We all agreed. 

That’s the magic of natural light: it forces you to be creative, and this set-up would not have been shot if not for what happened. It’s nerve wracking, but it’s also the most beautiful thing. That shoot is one of my favorites. 

For the studio shoots we often did work a bit backwards, shaping a single light, proposing different levels of contrasts on the same setup by closing windows halfway or bouncing white, then black on the next bracket.

It’s easier when you can blackout the outside: that gives you some control over what’s going on. You expose lights separately, so the mix is less critical when shooting. Relatively so, as weather can still play a role. But it’s been the case in most locations we went to. Whatever we could black out, we did (more tape, more black fabric). 

When blacking out wasn’t possible, we had to use lights so that inside and outside weren’t so far apart in exposure value. It’s a delicate balance that requires you to keep a sense of beauty and architecture by creating fake light entries behind walls, and glass doors, and so on.

We mostly use LED lights on these location setups. Fresnels and Sypanels, things that would be similar to what we used in tungsten. LEDs light up and switch off quite quickly, so you can dim them without changing their color temperature, which is adjustable itself. Even better, they don’t get hot which helps a lot when you have a lot of them around. 

But they’re heavy and expensive, and the available range of power is more for video work at higher ISO than what we do (80iso for the 360 camera and 100iso for the 35mm camera). Still, it was great to use them even sparingly, and they did mix well in the type of environment we were in.

The team

I built the team over time. My first assistant Symphonie Steinmetz came first. She is one of the most demanded photo assistants in Paris and one of the best I’ve worked with. She’s got tons of experience with big sets, and grip rigs; she’s a hard worker and super fun. 

Linda Leonard is our digital operator. She runs the capture setup, computers and cameras, organizes files, names them, enters all the data and measures, on set, to logs that were built with the team at Substance. Everything is uploaded to them as we go. 

Linda sees everything; she is a photographer herself and has worked as a photo assistant and producer in the past. She won’t let us make a mistake; if we do, she makes us redo everything. She’s tough, bullet proof. But she can be a lot of fun as well, when all is done and everything is packed.

These 2 and myself communicate a lot prior to the shoot and we get on set on the same page knowing what will be done. We also have a couple other assistants depending on what we do then and recently added Elodie Caillaud who overlooks production, locations, scouting, catering, equipment deliveries and budgets. She’s been a great help getting out of the studio, as things are getting heavier technically and logistically.

Backplates are post-produced by Emilie Holtz. She cleans bits, mostly imperfections in the floors, walls, backgrounds and then we sit together and play with a bit of contrast and density, color and saturation, so that a same set-up has the same feel throughout the 4 or 5 backplates, for maybe 2 or 3 IBLs on that location, exactly like we do it for conventional photo shoots. It’s like color-grading a movie, more or less.

Conclusion

I first got into this project as I was newly involved in cgi productions and starting to talk to potential clients of my interest in the medium, as a photographer. It’s been a wonderful experience and I know now  I won’t go back. I want to make more pictures with it. 

The Substance team is made up of amazingly sharp people. I can’t thank them enough. I grew a lot throughout this process and the Substance team been receptive, and willing to listen; they’ve driven the big picture, while leaving me and my team a great deal of creative freedom. I can’t wait to experience their final product. I know it will help me and fellow photographers (and creatives in general) to create CG photographs with new depths of quality. Together, I believe we’ve created a new photographic discipline, a way of capturing and making light available to most. I am grateful for the opportunity, and for the creative advantages it will offer.

The Substance team thanks Lionel for sharing his expertise, suffering through numerous iterations with us, and believing in the project!


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