第二部分
Video Content & Experiments
Perhaps the most interesting "khronos projected" videos are those which are able to produce simple spatio-temporal paradoxes and/or unusual visual effects. Irreversible phenomena are an interesting subject to shoot. As with the conventional cinemascope, these sequences can be shown backward in time, but new, unusual effects can be brought with the Khronos projector. This is possible by shooting sequences where time and space remain orthogonal narrative parameters. |
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Click on image to launch video [MOV- 752KB] |
Click on image to launch video [WMV- 5.6MB] |
In this sense, the Khronos projector is a suggestive tribute to Einstein's Theory of Relativity: the temporal relationship between two physically separate events is a perception relative to the observer. Now, the Khronos installation is no more -and no less- than a suggestive tribute to the theory (in its 100th anniversary!) because it only describes through a metaphor an otherwise well established scientific fact: that the universal Time Arrow is just an illusion, "although a convincing one" as Einstein himself put it.
In any case, it is not a serious platform for recreating any typical Relativity paradox, because the interactive projection infringes one fundamental law of Nature: although it is true that temporal relationships are relative to the observer's inertial frame, causality is not relative (this follows from the fact that information cannot travel faster than light). Two events that are in causal relationship should therefore always maintain their temporal order. The Khronos projector breaks this rule, but this is precisely what makes the experience interesting and fun! |
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Also, the result of visualizing simple gestures using the Khronos projector can be strikingly weird, probably because our visual system is fed with information that almost make sense - but for some subtle, continuous disturbance on the temporal coordinates of each pixel. The result of this reconstruction effort is that sometimes the deformation is no longer interpreted as the result of an isometric rotation or translation of the whole subject, but instead as a tremendously deformed gesture.
There are some interesting things to explore here concerning the emotional response to such "impossible" gestures, and perhaps the Khronos Projector can effectively be used to explore some cognitive aspects concerning our visual system (for instance, how motion is integrated in the process of face recognition). |
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Exploring Time Lapse photography with the Khronos Projector.
Time lapse photographic sequences are formed by taking a snapshot every minute, hour or day, from a fixed camera shooting at a natural or artificial landscape. Some classic examples are a one hour sequence of a sunset over the sea (e.g. one snapshot per minute), a 12 hours shooting of a city as seen from a skyscraper (e.g. one picture every five minutes), etc. Interesting effects may result from the gradual change of skyscraper's shades, the reflection of the Sun on the windows, the changing color of the sky and the lights on the streets, etc..
For instance, in the image on the right a “Time-Punch” brings the night as a dark eye in the middle of the sky. More simply (and classically), a spatio-temporal gradient can be formed on the image by selecting a plane temporal filter. The source material for these images is a time-lapse photographic sequence lasting for 3 hours, with a 3 minutes interval between frames. The view is from an apartment with a dominating view over central Tokyo. |
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Click on image to launch video [WMV- 6.9MB] |
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A bunch of interesting experiments can be performed by just tuning a few parameters of the Khronos program. These experiments may produce curious and aesthetic effects, or represent an interesting interactive experience per se. They also point at some ideas that may help contriving a custom-tailored movie for the Khronos projector. These options will remain invisible during the exhibition so as to avoid confusion and reduce the interaction-learning time to an absolute minimum (no learning necessary at all, only intuitive interaction by "pressing" the screen). Some pre-tuning will be operated beforehand, so as to simplify and purify the interactive experience. Parameters can however be changed from time to time.
- Painting with Time: by slowing down the reaction time of the temporal surface filter, it is possible to hold for a while the time coordinates at different parts of the scene. Time is spread by the user like oil on a canvas. (A "gravity effect" is also implemented that produce a temporal smearing of the image towards the bottom).
- Bright Future mode: brightness of the image is proportional to the temporal coordinate, such that the present is totally black, and the last image of the sequence is normally lit. This enhances the feeling that the future is being "discovered" (the opposite, i.e., "Dark Future" mode produces a quite disturbing feeling, metaphorically rendering our impossibility to see the future).
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- Minimalistic temporal filters: for instance defining the cutting surface as simple square windows, and making discrete the way it translates in time and space too. The image is therefore decomposed on cubistic square-shaped islands of time, producing a "Vasarelesque" Sam Loyd's spatio-temporal Fifteen.
- Time-tunneling: rapid background relaxation: the user only sees the future in a very small window, and has to rely on memory to reconstruct a ubiquitous-now. In an extreme situation, we get the effect of a shower of time-bullets all over the image.
- Aging Saturation: other parameters have been implemented allowing for instance to produce subtle changes in the color of pixels as these merge in time; for instance, in "Aging Saturation" mode, going back in time will de-saturate colors, so the portion of the image would turn grayscale, somehow reminding us of "old" times of black and white photography.
- Spatio-Temporal Ripples: the spatio-temporal disturbance propagates on the screen as water-like waves (see image on the right).
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- Chromatic Time Arrow. The Khronos Projector interactively "mixes" time and space; however, it is also possible to mix other "spaces" - for instance the color space, the motion-flow field... or even higher-level semantic spaces such as the result of a segmentation of the image based on face or gesture recognition, etc. Time would "freeze" around a sad face, or accelerate around the shape of a person running. A (rather simple) example of per-pixel luminance/time entanglement (speed of time evolution is controlled by the pixel luminance) can be seen by clicking on the image on the left. It is interesting to note that the projection will either converge to a final static image, or cycle around a finite set of images.
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Click on image to lauch video [WMV, 9.6MB] |
- Video and LIVE Video modes. The Khronos Projector is usually set so as to display the first image of the sequence when there is no physical interaction with the screen; although I believe this contributes in a meaningful way to the purpose of an installation (i.e. the user controls Time), the Khronos Projector features also two other modes: Video and Live Video modes. In the first mode, the images in the buffer are streamed onto the screen, and people can interact with this pre-recorded video content by accelerating or decelerating sections of the moving image (click on image to launch video [WMV, 23MB]).
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- Alternatively, in Live Video mode, the spatio-temporal volume of data is updated in real time through a webcam sitting in the exhibition room or somewhere else. At any given time, the spatio-temporal volume will be formed by a set of snapshots taken every minute during the last 12 hours, or every fraction of a second during the last minute. At every capture, a new picture is added to the pool of images, while the oldest is discarded - forming a first-input first-output buffer of images (an idea inspired from the Last Clock art-installation [7]). This way, the Khronos projectors will display a live video in the absence of interaction (click on images to launch video [WMV, 22MB] and [WMV, 21MB] ).
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Video & Snapshots Examples
The sequences fed to the program may be composed of several hundred high-resolution images; it is not the number of images that slow-down the real-time rendering, but the size of the images, since the temporal fusion algorithm must sequentially treat every pixel (when not using 3D textures). Using an Athlon 64 Processor 2.2 GHz (roughly equivalent in computing power to a Pentium 3GHz) with a 3D graphic acceleration card NVIDIA GeForce 6600 (512MB), the temporal fusion algorithm achieves smooth real-time rendering (both in 2D or 3D mode) for VGA (640x480) images with 32 bit color resolution. Much higher resolutions can be used to produce high-quality snapshots for printing purposes for instance. Click here or on the images to see many video-demos & snapshots of the Khronos Projector in action. |
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多点触摸技术3（外文）
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