Fluid – Cistern

A panorama above dark water in an underground cistern

VisualisationIndustryFree spatial study

Visualisation of a fictional space – not a realised project.

An underground cistern of 80 × 45 metres, a forest of columns above black water. On the north wall, “Spalten” from the Fluid series runs as a band across three projections – 45 metres wide, mirrored in the surface of the water.

From the entrance, a six-metre-wide timber walkway leads straight ahead to a platform in front of the image, both 60 centimetres above the water. The columns stand on a seven-metre grid and leave the line of sight clear. The image begins one and a half metres above the waterline; its reflection doubles the height and dissolves the wall.

Visitors gather on the platform and along the walkway. Between the columns it remains dark – only the light of the work traces the columns, handrails and people.

Technical details

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

Three Barco UDX-4K40 FLEX projectors with R9862001 TLD+ 90° ST lenses (0.65-0.85), 0.72-0.94 on the UDX-4K, 40,000 lumens each, hang from cross trusses. Each partial image measures 15.00 × 8.44 m with its bottom edge at 1.50 m; the throw distance is 12.45 m (throw ratio 0.83:1, lens shift -57% vertical). Calculated luminance on the wall: approx. 101 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: underground cistern with a forest of columns above water, timber walkway and platform
Configuration: three landscape images side by side from one video (band from the centre of the image)
Visitors (approx.): 110

Room	Width	Depth	Height
Cistern	80 m	45 m	12 m
Walkway	6 m	33 m	11.4 m
Platform	24 m	6 m	11.4 m

Projection

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

3 × Projector

15 m × 8.44 m per image

Bottom edge: 1.5 m
Distance: 12.45 m
Throw ratio: 0.83 : 1
Lens shift: -57 % 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.

3 × Barco UDX-4K40 FLEXbright enough

Luminance: 101 cd/m²
Target value: 60 cd/m²
required luminous flux: 31,013 lm
Luminous flux: 40,000 lm

Equipment

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

Barco UDX-4K40 FLEX

Lens: R9862001 TLD+ 90 Grad ST (0.65-0.85), am UDX-4K 0,72-0,94
Luminous flux: 40,000 lm
Weight: 92 kg

Alternatives (3)

Model	Lens	Luminous flux	Luminance
Barco QDX-4K45	R9862001 TLD+ 90 Grad ST (0.65-0.85), am QDX-4K 0,67-0,88	45,000 lm	113 cd/m²
Panasonic PT-RQ35K2	ET-D3LEW300 (Weitwinkel-Zoom)	2 × 30,500 lm	153 cd/m²
Panasonic PT-RQ35K2	ET-D3LEW200 / ET-D3LEW201 (Kurzdistanz-Zoom)	2 × 30,500 lm	153 cd/m²

Price range and equipment list on request.

Drawings

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

Fluid – Cistern — Axonometric view — **Axonometric view** · not to scale

Fluid – Cistern — Floor plan — **Floor plan**

Fluid – Cistern — 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.