Sculpt Color – Salt Cavern

A work of 36 × 20 metres deep inside the mountain

VisualisationIndustryFree spatial study

Visualisation of a fictional space – not a realised project.

A rock cavern of 90 × 45 metres and 35 metres high, deep inside the mountain. On the end wall, “Würfelringe” from the Sculpt Color series hovers – 36 × 20 metres on four large-format projectors, a coloured object before dark rock.

The cavern is reached through a long access tunnel lined with faint mine lamps. Two massive rock pillars support the ceiling and frame the view. The work runs as one video on a grid of 2 × 2 projections, with the bottom edge at four metres; because the work stands on a black ground, the edge of the image merges with the rock.

Around 140 visitors stand on the gravel floor in front of the wall. The coloured light falls on the rough rock surface and on the people – a space older than any architecture carries an image made of pure light.

Technical details

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

Two Barco QDX-4K45 projectors with R9862001 TLD+ 90° ST lenses (0.65-0.85), 0.67-0.88 on the QDX-4K, 45,000 lumens each, hang from cross trusses. Each partial image measures 18.00 × 10.13 m with its bottom edge at 14.13 m; the throw distance is 15.00 m (throw ratio 0.83:1, lens shift -56% vertical). Calculated luminance on the wall: approx. 79 cd/m². Two Barco QDX-4K45 projectors with R9801414 TLD+ lenses (0.8-1.16), 0.86-1.25 on the QDX-4K, 45,000 lumens each, hang from cross trusses. Each partial image measures 18.00 × 10.13 m with its bottom edge at 4.00 m; the throw distance is 16.80 m (throw ratio 0.93:1, lens shift -156% vertical). Calculated luminance on the wall: approx. 79 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: rock cavern inside the mountain with access tunnel, rock pillars and mine lamps
Configuration: one video on 2 × 2 large-format projectors
Visitors (approx.): 140

Room	Width	Depth	Height
Cavern	90 m	45 m	35 m
Mine tunnel	6 m	25 m	6 m

Projection

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

2 × Projector

18 m × 10.13 m per image

Bottom edge: 14.13 m
Distance: 15 m
Throw ratio: 0.83 : 1
Lens shift: -56 % vertical
Mounting: on the truss

2 × Projector

18 m × 10.13 m per image

Bottom edge: 4 m
Distance: 16.8 m
Throw ratio: 0.93 : 1
Lens shift: -156 % 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.

2 × Barco QDX-4K45bright enough

Luminance: 79 cd/m²
Target value: 60 cd/m²
required luminous flux: 44,659 lm
Luminous flux: 45,000 lm

2 × Barco QDX-4K45bright enough

Luminance: 79 cd/m²
Target value: 60 cd/m²
required luminous flux: 44,659 lm
Luminous flux: 45,000 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: 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	140 cd/m²
Panasonic PT-RQ35K2	ET-D3LEW300 (Weitwinkel-Zoom)	2 × 30,500 lm	107 cd/m²
Panasonic PT-RQ35K2	ET-D3LEW200 / ET-D3LEW201 (Kurzdistanz-Zoom)	2 × 30,500 lm	107 cd/m²

Barco QDX-4K45

Lens: R9801414 TLD+ (0.8-1.16), am QDX-4K 0,86-1,25
Luminous flux: 45,000 lm
Weight: 77.5 kg

Alternatives (3)

Model	Lens	Luminous flux	Luminance
Christie Griffyn 4K50-RGB	144-111014-XX ILS4 0.9:1 HB fest (UHC: 163-117100-XX)	50,000 lm	87 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	140 cd/m²
Barco UDX-4K40 FLEX	R9801414 TLD+ (0.8-1.16), am UDX-4K 0,92-1,33	2 × 40,000 lm	140 cd/m²

Price range and equipment list on request.

Drawings

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

Sculpt Color – Salt Cavern — Axonometric view — **Axonometric view** · not to scale

Sculpt Color – Salt Cavern — Floor plan — **Floor plan**

Sculpt Color – Salt Cavern — 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.
Synchronised output: Several projectors show parts of the same image; one computer outputs them simultaneously – computed live or as video.