A live reconstruction in space and time. Every recorded moment of a black cat climbing a flight of stone stairs in an alley at night is shown at once as a trail of points; the present moment is highlighted, cyan when time moves forward and amber when it rewinds. A cone marks the camera that filmed it, with the frame it saw. The wall nearest to you is cut away so you can see in. The scene is synthetic.

4D.OS

Hanging the exhibit

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Timeline Source ···

00:00:00
HOLD 0.00×

Every moment
at once

PlanRoom 4

Cat Camera

ClockSource

00:00:00

Frame 000 of ···

Camera 1What it saw

Label

Cat, climbing

4D.OS after J-Toastie, 2026

Point cloud, dithered live

Frames
···
Moments
···
Ground
···
Weight
···

"Cat" by J-Toastie, CC-BY 3.0. Animated by 4D.OS.

4D.2026.001

Layers

Time
Show

Display

Colors

A black cat climbed a flight of stairs in fourteen seconds. All fourteen seconds hang here at once.

Film anything moving, rebuild every frame in three dimensions, and leave each one where and when it happened. What you get is not a model of the cat but a record of its passage: the rooms that follow show how.

Room 5

2D + time = 3D

Conway's Game of Life. Each generation of a glider is stacked above the last; the newest is the brightest.

A flat world that changes over time is already a solid. Stack its moments one above the other and time becomes a third dimension: the glider's walk across the grid turns into a staircase you could hold.

A 4D reconstruction does the same one dimension up. Each frame of a video becomes a small 3D scene, and the scenes are stacked along time. You cannot see four dimensions, so the case in Room 4 shows them the way this tower shows three: every moment at once.

Room 6

From video to space and time

  1. A 2D video

    One camera films the subject. Every frame is a flat picture with a known position and direction.

  2. 3D, frame by frame

    Each frame is rebuilt as points in space: one small sculpture per moment.

  3. Left where and when it happened

    Nothing is moved or merged. The moments stay where they were recorded, and together they draw the journey.

Room 7

Scroll is time

In this room you are the playhead. Scroll down to move forward, up to rewind.

00:00:00 HOLD 0.00×

Room 8

Measurements

Read from the pack now loaded in your browser, not typed by hand. Load another pack and these lines change.

Frames
··· at ···
Duration
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Moments of the cat
··· points, ··· per frame
The alley
··· points, drawn once
Points in the case
···
Weight on disk
···
Source frames
···

Room 9

Other subjects

Room 10

Questions

What am I looking at?

Every moment of a short clip, rebuilt in three dimensions and left in place. The trail is the cat's past; the highlighted cat is the present; the cone is the camera that filmed it, showing the frame it saw. The wall nearest to you is cut away so you can see into the alley.

Is it real?

No. This scene is synthetic, and it is labelled that way wherever it appears. It was made in the browser from a free 3D cat so the viewer could be built before real captures exist.

Why does it look like an old computer?

Because the old desktop already had this idea: drag a window and it leaves copies of itself behind. That trail is the flat version of the one in the case. The look is drawn live, not from recorded animations.

Why is it pixelated?

The case is rendered at a third of your screen's resolution and each pixel is enlarged without blurring. Colors are reduced to 16 (or 2) with ordered dithering. Switch the Display window to Millions to see it without the treatment.

Can I move through time myself?

Yes. Drag the timeline, press space to hold or resume, J and L to rewind or play faster, K to hold, and the arrow keys to step one frame. Drag inside the case to walk around it.