Multi-Frame 3D Photography

written for the stereosite by Michael Brown, USA

Clas­sic stereo pho­tog­ra­phy gen­er­al­ly con­sists of a pair of expo­sures tak­en from two sep­a­rate posi­tions cor­re­spond­ing to the views that would be seen by each of the two eyes. Image pairs have tra­di­tion­al­ly been viewed using a stere­o­scope or alter­nate meth­ods that could include 3D glass­es (anaglyph or polar­ized), or free view­ing (par­al­lel or cross eyed).

In the ear­ly part of the last cen­tu­ry researchers worked to cre­ate tech­niques that would allow for cre­at­ing 3D pic­tures that didn’t require stereo­scop­ic view­ing aids. Pio­neers such as Lipp­man, Ives , & Kanolt cre­at­ed what we now refer to as 3D Lentic­u­lar pho­tog­ra­phy. These sci­en­tists and oth­ers exper­i­ment­ed with dual images, image sequences, black/clear bar­ri­er tech­niques, fly’s‑eye lens­es, and many oth­er approach­es. Ulti­mate­ly, the most prac­ti­cal method for cre­at­ing auto-stereo­scop­ic prints uti­lized a frame series tak­en from dif­fer­ent hor­i­zon­tal posi­tions, and a clear lentic­u­lar lens sheet uti­liz­ing ver­ti­cal lentic­u­lar elements.

Lentic­u­lar pho­tographs can be viewed the same way as ordi­nary pho­tos, but they show the added dimen­sion of depth. No stere­o­scope or 3D glass­es are required for view­ing. This ease of view­ing is the biggest ben­e­fit of the lentic­u­lar print. If only two stereo views were used for a lentic­u­lar, the print would have to be held at a very pre­cise dis­tance and pre­cise angle to be seen. By adding more view­points, the prints are eas­i­ly viewed from a vari­ety of posi­tions and angles. That is why lentic­u­lars are cre­at­ed with more than two stereo viewpoints.

I became inter­est­ed in 3D Lentic­u­lar pho­tog­ra­phy in 1982 when I read about and lat­er pur­chased a Nim­s­lo 4- lens 35mm cam­era. The Nim­s­lo was a 35mm film cam­era that cap­tured 4 pic­tures occu­py­ing the space of two stan­dard film frames. After the film was exposed, it was sent to a photofin­ish­ing lab for devel­op­ment and print­ing. There was no method in the 1980s for print­ing your own Nim­s­lo negatives.

Around 2005, I learned that dig­i­tal image pro­cess­ing had advanced to a point where it was pos­si­ble to make lentic­u­lar prints with desk­top inkjet print­ers. Lentic­u­lar lens sheets were also now com­mer­cial­ly avail­able in small quan­ti­ties. Using infor­ma­tion gleaned from the Inter­net, I began my exper­i­men­ta­tion. Although I could scan the four film frames made with a Nim­s­lo cam­era to make a 3D lentic­u­lar print, I decid­ed I would rather cap­ture my pho­tos with a dig­i­tal camera.

I now use two tech­niques for my 3D lentic­u­lar pho­tog­ra­phy. My pri­ma­ry approach is to mount a dig­i­tal cam­era on a one-meter slide bar and shoot a sequence of frames as I moved the cam­era from one side to the oth­er. There is noth­ing mag­i­cal about the one-meter length. It works fine for my por­trait sub­jects that typ­i­cal­ly sit about 2 — 3 meters from my cam­era. Close up sub­jects require less hor­i­zon­tal off­set and dis­tant sub­ject more. My cam­era has a burst depth of about 70 frames before the buffer is full. I gen­er­al­ly use a sub­set of those frames (typ­i­cal­ly more than 10 and few­er than 40). The num­ber of frames I use relates to the size of the fin­ished print, the observer’s view­ing dis­tance, the view­ing angle of the lentic­u­lar lens sheet, and whether sharp­ness or depth is more impor­tant in the fin­ished result. Typ­i­cal­ly, the total base between the first and last expo­sure is gen­er­al­ly 3–6 times the nor­mal base for clas­sic stereopho­tog­ra­phy. So for stu­dio por­trai­ture, using a cam­era on a slide bar, I gen­er­al­ly move the cam­era about 15 inch­es from one side to the other.

My sec­ond approach is to use four small Sony RX0ii cam­eras mount­ed on a bar which allows me to pho­to­graph instan­ta­neous sub­jects. The cam­eras are syn­chro­nized using an Esper Con­trol box. There is con­stant debate on how accu­rate the sync is with Sony cam­eras. I have found the sync is fine for the sub­jects I tend to pho­to­graph – peo­ple. Some­times I make prints with just the four frames and oth­er times I will inter­po­late in-between frames using Adobe After Effects Time Warp func­tion. So for exam­ple, I can turn four frames into a dozen or more. Oth­er 3D pho­tog­ra­phers have built mul­ti­ple cam­era rigs with a dozen or more cameras.

Once a sequence of frames is cap­tured, the next step is mak­ing the 3D Lentic­u­lar print. The mul­ti­ple frames are com­bined by inter­lac­ing them in ver­ti­cal strips using soft­ware – for Exam­ple Tri­ax­es 3DMasterkit. The inter­laced file can be print­ed with an inkjet print­er and bond­ed to a lentic­u­lar screen. The result is a print you can see in 3D. The many details of this process are beyond the scope of this arti­cle, but the inter­net is a good source of information.

To bet­ter illus­trate the con­cepts expressed I thought it might be help­ful to look at the process of mak­ing a lentic­u­lar por­trait. In this exam­ple I mount­ed a Canon 1Dx cam­era on a slid­er. The mod­el was illu­mi­nat­ed with two LED lights shoot­ing through white umbrel­las. I select­ed a high ISO for the cam­era because the lights were not very bright, and a short shut­ter speed to pre­vent blur as I moved the cam­era along the slid­er. The pho­to­graph­ic para­me­ters for the 37 frames cap­tured were: Focal length 50mm, Expo­sure: 1/320 sec­ond; f/8, ISO 3200.

You can view GIF ani­ma­tions of my 3D lentic­u­lars at my web site. I have also many videos of the lentic­u­lar print process and addi­tion­al edu­ca­tion mate­r­i­al avail­able on my YouTube-chan­nel. I also rec­om­mend to vis­it the Face­book-group Lentic­u­lar Art, Print­ing, & 3D pho­tog­ra­phy.