How Projection Mapping Works: From 3D Measurement to Projection, Blending and Sound Synchronization

Projection mapping is a form of expression in which images created to fit the shape of a building or other object are projected on top of that shape. In the permanent show on the Tokyo Metropolitan Government No. 1 Building, 40 projectors cover a wall about 110 m wide and about 126 m high. Drawing on manufacturers’ technical materials, research papers and organizers’ announcements, this article explains the three processes of “measuring” the target, “creating” the images and “projecting” on site, along with the flow through to sound and operation.

There is also the method of checking how things will look on a scale model before the show. In 2014, ahead of the launch of a show projecting images onto Cinderella Castle, Tokyo Disneyland released test footage projected onto a 1.5 m-tall model of the castle (about 1/30 scale).

The key points of the process can also be seen in the criteria used to evaluate works. The Tokyo International Projection Mapping Award (PMA TOKYO), whose final is on Saturday, November 14, 2026, projects works of up to 1 minute 30 seconds onto the inverted-triangle exterior wall (94 m wide × 30 m high) of the Conference Tower at Tokyo Big Sight. The entry guidelines list “planning,” “concept,” “technique,” “staging” and “production” as judging criteria, looking at whether works make use of the features of the projection surface and the building, and whether they make use of the fusion of music and images.

Measuring: Turning the shape of an object into data

The first process is turning the shape of the projection surface into data. The 2001 paper “Shader Lamps” (Ramesh Raskar et al.), describing experiments in giving color and texture to white objects with light, began by measuring the three-dimensional shape of the objects. It used a contact-type 3D digitizer with an accuracy of 0.5 mm, taking about 30 minutes to measure one object.

The measured shape becomes data made up of triangles. A clay vase about 12 × 12 × 35 cm was represented by 7,000 triangles, and a white-painted wooden model of the Taj Mahal about 70 × 70 × 35 cm by 21,000 triangles.

Methods for measuring large targets such as buildings have been organized in the field of documenting cultural properties. In a 2019 research report, Akihiro Kaneda of the Nara National Research Institute for Cultural Properties divides laser scanners into three main methods: the ToF (time-of-flight) method, which measures the time from emitting a laser until it returns; the phase-shift method; and the triangulation method, which uses triangulation.

According to Kaneda, the ToF and phase-shift methods are resistant to outside light and can measure wide areas but tend to be less accurate. The triangulation method is highly accurate but vulnerable to the outside environment and is used mainly indoors. Highly reflective objects and glass, where light reflects many times, can be difficult to measure. At the Sakurada IV site in Fukushima Prefecture, a building site of more than 800 m² was measured in half a day using the phase-shift method.

There is also photogrammetry, which reconstructs shapes from photographs. It combines SfM (Structure from Motion), which determines camera positions and shapes from multiple images, with MVS (Multiview Stereo), which computes a dense collection of points (point cloud) from the results. While many methods require dedicated equipment, Kaneda writes that its advantage is that measurement is possible by adding software to a commercially available computer and camera.

Creating: The projector’s point of view and the illusion of depth

Once the shape data is ready, the positional relationship with the projector is determined. The Shader Lamps paper treated the projector as a perspective projection device like a camera and used the approach of camera calibration from computer vision. The centers of projected crosshairs were aligned one by one with about 20 markers whose 3D positions on the object were known, and a 3 × 4 projection matrix was computed from those correspondences.

According to the paper, a projector has up to 11 degrees of freedom, including position, orientation and lens properties, making manual alignment laborious. With this method, each projector could be calibrated in under five minutes, with errors typically under two pixels. Once the positional relationship is known, it is possible to calculate which pixel’s light falls on which point of the object.

Brightness correction is also needed. The paper expressed the projection intensity needed to achieve a target appearance with a formula proportional to the square of the distance and inversely proportional to the surface reflectance and the cosine of the angle at which light strikes the surface. It set surfaces angled more than 60 degrees not to be lit, preserving the brightness range and avoiding misalignment.

In staging the images themselves, the illusion of depth is key. In an explanation in the academic journal “Kogaku” (Japanese Journal of Optics, 2014), Michiyuki Ishita of the Projection Mapping Association of Japan says that projecting three-dimensional-looking images matched to a round shape makes a flat object look three-dimensional, and that adding light and shadow further enhances the sense of space and depth.

Some works change their images in response to people’s movements. Writing in the academic journal “Shikisaigaku” (Journal of the Color Science Association of Japan, 2024), Maya Oguri of Aichi Institute of Technology introduced a projection onto shoji screens that used Kinect to capture visitors’ skeletons, with paper charms modeled on “ee ja nai ka” falling when visitors waved their hands. In a Japanese-style room for a tea ceremony, a laser range sensor detected feet, and leaves projected onto the tatami danced as visitors walked.

Projecting: Brightness, unit count, blending and geometric correction

Covering a large surface brightly depends on the combination of unit count and brightness. According to a Panasonic Connect announcement, the permanent show on the Tokyo Metropolitan Government Building uses 20 units each of the 50,000-lumen “PT-RQ50KJ” and the 30,500-lumen “PT-RZ34KJ,” both 3-chip DLP laser projectors. According to the official website, the area recognized by Guinness World Records as the “largest projection mapping display on a building (permanent)” is 13,904.956 m².

Indoor immersive venues envelop walls and floors with even more units. According to a September 2025 announcement by TV Asahi, “RÊVE DES LUMIÈRES” in Ariake, Tokyo, uses more than 100 projectors, centered on Epson’s 13,000-lumen “EB-PU2213B,” and about 60 speakers in a space of about 1,200 m². Outdoors, a 2013 event in front of Kashiwa Station in Chiba Prefecture projected onto a 68 m-high wall with eight units: two 35,000-lumen and six 20,000-lumen projectors (Ishita’s explanation).

“Edge blending” joins the images of multiple projectors. The edges of adjacent images are overlapped and joined so that the boundary is invisible. The Shader Lamps paper set out the principle of making the sum of each projector’s light weights equal one in the overlapping area and varying the weights smoothly. The manual for Epson’s throw distance simulator gives a default overlap (blend width) range of 15–45% and says the maximum width that can be set with the built-in function is 45%.

Distortions caused by curved surfaces or oblique projection are corrected with geometric correction. Epson’s high-brightness models offer “point correction,” which moves grid points one by one (up to 33 × 33 points on the EB-L30000U/L30002U), as well as correction for projection onto spherical and curved surfaces and onto corners. There are also functions that use a camera to automatically correct differences in brightness and color between multiple units (some models require an external camera), and “stacking,” which overlays images to increase brightness.

Panasonic includes correction for distortion when projecting onto spherical and cylindrical surfaces as standard in its projectors. Some models can use “Free Grid,” which corrects local distortion with grids from 2 × 2 to 17 × 17. The company says this supports staging from large cylindrical and spherical screens to mapping onto huge buildings. Recent developments in projectors, such as higher brightness and RGB lasers, are summarized in our article on laser projector trends 2026.

Sound and operation: Synchronization, loops and remote monitoring

Techniques for running images, sound and lighting on time go back to the “son et lumière” (sound and light) shows of the 1950s. According to a 1990 research report published by ENSSIB, in early performances operators switched lights according to circuit numbers written in the script. Later, control signals were recorded on spare tracks of multitrack tape, moving to automation in which lights switched at set moments. The history is traced in our article on the history of projection mapping.

Today, dedicated devices and software for controlling images, music and lighting (media servers) are used (the “Kogaku” explanation). The Tokyo Metropolitan Government Building show uses RAMSA spatial audio equipment linked to the projectors, and the projected content is managed remotely with a management system based on “AcroSign.” Remote cameras are used to check the projection, and equipment status is also monitored online (Panasonic Connect).

There is also ingenuity in how sound is delivered. The official website of the metropolitan government building show, “TOKYO Night & Light,” lets visitors play the same music as on site during screenings (except for some works). Screenings take place daily except in severe weather, with eight shows scheduled between 17:30 and 21:30 in November. The official website also notes its use of green electricity. Works and show times are compiled in our guide to TOKYO Night & Light.

Outdoor events are often operated by repeating footage of a fixed length. In 2025–2026, Matsumoto Castle projected about nine minutes of footage continuously, with breaks of about three minutes. “AICHI NAGOYA ART & LIGHTS” at the Aichi Prefectural Government building and Nagoya City Hall alternated about five minutes of projection with about five minutes of light-up. Tokyo Disneyland’s castle projection, launched in 2014, was a roughly 15-minute show combining images with lasers, searchlights and small fireworks.

Conditions for projecting outdoors: Darkness, surfaces, weather and flashing

How a projection looks depends on the surrounding brightness. The Shader Lamps paper cited as the method’s main constraints its dependence on the properties of the projection surface and the need for dark, controlled ambient light. Matsumoto Castle’s 2025–2026 announcement also cautioned that later in the season, as sunset came later, the projection might be hard to see at the start of the show.

The color and material of the surface also matter. Ishita writes that transparent objects and black walls are normally difficult to project onto, but can be made clearly visible by applying high-brightness reflective film. Epson’s simulator also cautions that its brightness and contrast results are calculated values and do not guarantee actual values.

Preparing for weather is also essential. For the metropolitan government building show, a dedicated housing with seismic, waterproof and dustproof performance was developed for permanent outdoor installation. Matsumoto Castle projects even in rain or snow and Tsuruga-jo Castle in rain, though both say shows may be interrupted or canceled in severe weather. Projection methods, ceiling mounting and laser safety distances are explained in our article on how to install projectors.

The content of images also calls for consideration of the surroundings. The Tokyo Metropolitan Government’s “Guidelines on the Display of Projection Mapping” limit flashing of images and light to, in principle, three times per second and call for particular care with flashing vivid red. When projecting across a road, they also require confirming that the display does not impair the function of traffic signals or road signs and does not dazzle drivers.

Editor’s perspective

Breaking down the processes shows that projection mapping is at once a visual work and a combination of surveying, optics and operational technology. The scale varies, from 40 units at the metropolitan government building to more than 100 in Ariake and 8 in Kashiwa, but the procedure of knowing the shape, aligning positions and adjusting brightness and seams is common to all. The flow from planning to the show and a breakdown of costs are summarized in our article on the process of staging projection mapping.

Equipment correction functions have advanced, but conditions such as the properties of the projection surface and the darkness of the surroundings overlap with the constraints cited in the 2001 paper. When cultural properties become the stage, constraints on equipment placement and power supply are added. Those considerations and public guidelines are set out in our article on projection mapping on cultural properties and the care it requires.

Frequently asked questions

How many projectors are needed?

It depends on the size of the surface, the brightness required and the models used. In this article’s examples, the metropolitan government building used 40, RÊVE DES LUMIÈRES in Ariake more than 100, and the 2013 event in front of Kashiwa Station 8. “TOKYO STATION VISION” on the Marunouchi Building of Tokyo Station in 2012 projected onto the 120 m-wide, 30 m-high station building with 46 ultra-high-brightness projectors.

What is the difference between edge blending and geometric correction?

Edge blending is the process of smoothly joining the overlaps of images from multiple projectors. Geometric correction refers to the process of fixing distortions caused by curved surfaces or oblique projection. Professional models from Epson and Panasonic can both be adjusted with built-in functions or dedicated software. Companies that plan and produce events using such equipment are introduced in our article on production companies.

Can I go to see the work contests?

The final of the Tokyo International Projection Mapping Award Vol.11 will be held on Saturday, November 14, 2026, in the plaza in front of the Conference Tower at Tokyo Big Sight. According to the official website, doors open at 16:30 and admission is free. The theme is “ReBORN,” and the teams advancing to the final are scheduled to be announced on October 30.

Articles organized by each stage of planning are gathered in our guide for those planning projection mapping and light events.

*Information as of October 21, 2026. Please check the official websites for the latest information.

Terms such as lumens, throw ratio and edge blending are briefly explained in our projection mapping glossary.

*Top image: “National Treasure Matsumoto Castle Keep Projection Mapping 2024–2025” (from HITOHATA, INC.’s press release)

*This article was compiled by the TOKYO ART SPHERE editorial team based on official announcements by each organizer and manufacturer and public materials from research institutions and government agencies (as of October 21, 2026).

Text: TOKYO ART SPHERE Editorial Team

A note from the publisher

*Disclosure: The “National Treasure Matsumoto Castle Keep Projection Mapping” in the top image and “AICHI NAGOYA ART & LIGHTS” and “Tsuruga-jo Castle Projection Mapping,” cited as examples in this article, are events in whose production HITOHATA, INC., an affiliate of HITOHATA ASSOCIATION, the general incorporated association that operates TOKYO ART SPHERE, took part (About us).

HITOHATA, INC., an affiliate of HITOHATA ASSOCIATION, the general incorporated association that operates TOKYO ART SPHERE, plans, directs, produces and operates projection mapping at National Treasures, Important Cultural Properties, World Heritage Sites and urban landmarks, as well as immersive exhibitions. Consultations also cover staging and equipment tailored to the conditions of a venue and projection surface. Inquiries, including those at the stage before a budget is set, are accepted through HITOHATA, INC.’s contact form (which has an option for local government and public projects). The company’s past work is introduced on HITOHATA, INC.’s project portfolio page.