Ring Quader – City Square

A façade projection of 66 × 25 metres above a square at night

VisualisationCityFree spatial study

Visualisation of a fictional space – not a realised project.

A city square at night, a sandstone façade 120 metres wide and 45 metres high. On it runs “Stille” from the Ring Quader series – 66 × 25 metres on six large-format projectors, above a square full of people.

The image occupies the centre of the façade; to the left and right, pilaster strips, cornices and dark rows of windows remain visible. Six projections in a 3 × 2 grid form a wide band from the centre of the work video; the bottom edge lies at eight metres, above the portal. Neighbouring buildings frame the square as dark blocks, and street lamps set warm points of light at its edges.

More than 300 people stand on the paving, close to the façade and loosely spread out to the edge of the square. The work becomes an event in urban space – a quiet movement above a crowded square.

Technical details

What it takes to build this space: dimensions, equipment, brightness.

Three image positions, each with two Barco QDX-4K45 projectors stacked in exact alignment (R9862001 TLD+ 90° ST lens (0.65-0.85), 0.67-0.88 on the QDX-4K, 45,000 lumens each), hung from cross trusses. Each partial image measures 22.00 × 12.38 m with its bottom edge at 20.38 m; the throw distance is 18.40 m (throw ratio 0.84:1, lens shift -55% vertical). Calculated luminance on the wall with stacking: approx. 105 cd/m². Three image positions, each with two Christie Griffyn 4K50-RGB projectors stacked in exact alignment (144-111014-XX ILS4 0.9:1 HB fixed lens (UHC: 163-117100-XX), 50,000 lumens each), hung from cross trusses. Each partial image measures 22.00 × 12.38 m with its bottom edge at 8.00 m; the throw distance is 20.60 m (throw ratio 0.94:1, lens shift -155% vertical). Calculated luminance on the wall with stacking: approx. 117 cd/m². Alternatives, price range and all dimensions per device are listed in the equipment list; floor plan, section and axonometric view show the projection cones.

Room

The room of the scenario and how the images are placed in it.

Room: city square at night in front of a sandstone façade, neighbouring buildings, street lamps
Configuration: 3 × 2 large-format projectors, wide band from the centre of the image (façade projection)
Visitors (approx.): 320

Room	Width	Depth	Height
Square	120 m	90 m	45 m

Projection

How the images are created: equipment, image size, distance and mounting.

6 × Projector

22 m × 12.38 m per image

Stacking: 2 projectors per image, precisely aligned
Bottom edge: 20.38 m
Distance: 18.4 m
Throw ratio: 0.84 : 1
Lens shift: -55 % vertical
Mounting: on the truss

6 × Projector

22 m × 12.38 m per image

Stacking: 2 projectors per image, precisely aligned
Bottom edge: 8 m
Distance: 20.6 m
Throw ratio: 0.94 : 1
Lens shift: -155 % vertical
Mounting: on the truss

All partial images belong to one picture – one computer outputs them simultaneously and frame-accurately.

Real time and interaction

The film shows a recording. In the installation the work is computed live – and can respond to the space and its visitors.

Computation: live, in real time, on a high-end computer with a powerful 3D graphics card, NVIDIA RTX 4070 or higher; with many image surfaces also with several graphics cards
Output: all projectors in a room from one computer, as coordinated zones rather than separate videos
Interaction: 3D LiDAR scanners capture people and movement in the space; the work can respond to them
Fitting: mapping to the actual architecture – edges, columns, ceilings and floors

Brightness

Whether the image will be bright enough: luminance achieved against the target value. The line in the bar marks the target value.

6 × Barco QDX-4K45bright enough

Luminance: 105 cd/m²
Target value: 60 cd/m²
required luminous flux: 66,713 lm
Luminous flux: 2 × 45,000 lm

6 × Christie Griffyn 4K50-RGBbright enough

Luminance: 117 cd/m²
Target value: 60 cd/m²
required luminous flux: 66,713 lm
Luminous flux: 2 × 50,000 lm

Equipment

The reference devices used for the calculations. Devices of the same class are equally suitable.

Barco QDX-4K45

Lens: R9862001 TLD+ 90 Grad ST (0.65-0.85), am QDX-4K 0,67-0,88
Luminous flux: 2 × 45,000 lm
Weight: 77.5 kg

Alternatives (3)

Model	Lens	Luminous flux	Luminance
Barco UDX-4K40 FLEX	R9862001 TLD+ 90 Grad ST (0.65-0.85), am UDX-4K 0,72-0,94	2 × 40,000 lm	94 cd/m²
Panasonic PT-RQ35K2	ET-D3LEW300 (Weitwinkel-Zoom)	3 × 30,500 lm	107 cd/m²
Panasonic PT-RQ35K2	ET-D3LEW200 / ET-D3LEW201 (Kurzdistanz-Zoom)	3 × 30,500 lm	107 cd/m²

Christie Griffyn 4K50-RGB

Lens: 144-111014-XX ILS4 0.9:1 HB fest (UHC: 163-117100-XX)
Luminous flux: 2 × 50,000 lm
Weight: 89.3 kg

Alternatives (3)

Model	Lens	Luminous flux	Luminance
Barco QDX-4K45	R9801414 TLD+ (0.8-1.16), am QDX-4K 0,86-1,25	2 × 45,000 lm	105 cd/m²
Barco UDX-4K40 FLEX	R9862001 TLD+ 90 Grad ST (0.65-0.85), am UDX-4K 0,72-0,94	2 × 40,000 lm	94 cd/m²
Barco UDX-4K40 FLEX	R9801414 TLD+ (0.8-1.16), am UDX-4K 0,92-1,33	2 × 40,000 lm	94 cd/m²

Price range and equipment list on request.

Drawings

Axonometric view, floor plan and section show the space and the projection cones.

Ring Quader – City Square — Axonometric view — **Axonometric view** · not to scale

Ring Quader – City Square — Floor plan — **Floor plan**

Ring Quader – City Square — Section — **Section** · not to scale

Glossary

Real time: The image is recomputed at every moment, about 60 times per second, instead of being played back as a finished video.
3D LiDAR scanner: Scans the space with laser light and captures people and movement in three dimensions – the basis of the interaction.
High-end computer: A computer with a powerful 3D graphics card – NVIDIA RTX 4070 or higher – that computes the image live and drives all projectors at once.
Mapping: Fits the projection to the actual geometry of the space so that image and architecture meet exactly.
Throw ratio: Distance divided by image width. At 0.8 : 1, the projector for an image 6 m wide stands 4.8 m away.
Lens shift: Shifts the image within the lens without tilting the projector – so it stays rectangular.
Luminous flux: How much light the projector emits, in lumens.
Luminance: How bright the image surface appears to the eye, in candelas per square metre. In a dark room, about 60 is enough.
Bottom edge: The height of the bottom edge of the image above the floor.
Stacking: Several projectors cast the same image exactly on top of each other. Their light adds up – so even very large surfaces become bright enough.
Synchronised output: Several projectors show parts of the same image; one computer outputs them simultaneously – computed live or as video.