4D - is it really?

[dsharp7th]

I hear "4D" and "4 Dimensional" being quoted in relation to complex building projections (such as the spectacular Deadmau5/Nokia at Millbank and

promotional events) usually in marketing and media coverage rather than technical descriptions.

 

Is there any technical justification for describing it as 4D? And is the term 4D ever used in technical, rather than marketing language?

 

Surely the fact that the projections are mapped onto multiple planes with depth just makes the result 3D instead of 2D... (Or is 3D not considered a futuristic enough descriptor by those at the cutting edge of projection mapping..?)

[the kid]

I only know of 4D to be 3D with "live" action, maybe seats move, or scents added etc etc. I believe several Disney theatres have wind and water added.

[Seano]

(Or is 3D not considered a futuristic enough descriptor by those at the cutting edge of projection mapping..?)

 

Maybe the recent War of the Worlds tour, widely advertised as "Starring LIAM NEESON in 3D Holography" (or to put it another way - back projected onto a screen that looks rather like a sheet of hamburg frost) has devalued the currency a little bit.

[ramdram]

Of interest?

 

http://en.wikipedia.org/wiki/Four-dimensional_space

 

if nothing else the gif looks pretty.

[Brian]

Is there any technical justification for describing it as 4D?

 

No. It is, to use the correct term , Arse-gravy of the very worst kind.

 

And is the term 4D ever used in technical, rather than marketing language?

 

Not by people who know WTF they are talking about.

[Andrew Edwards]

It is certainly not an extra dimension in Euclidean terms. However, the term dimension has multiple meanings.

 

Bear with me...

 

If you take anything and do something new to it you could argue that you have given it an extra dimension. Mr. Roux Jr and Prof. Blumenthal does this all the time with their truly amazing culinary skills.

 

The disney et al version of 4D is watching a 3D* projected image whilst being subjected to a whole array of mechanical effects. *A projected image where each eye sees a distinct image based upon 2 points of view which the brain combines to form depth which is very close to real life. It is not exactly like real life as the actual focus of the eye does not change.

 

Of course there is also 3D where perspective is used to create depth within a 2 dimensional image. Both eyes see the same image but the brain creates the depth based upon visual clues rather than the combination of two points of view.

 

The 'extra dimension' in the OP type of image mapping is cleverly compensating or exploiting the geometry of the surface you are projecting onto. It is a figurative dimension and I don't really have a problem with describing it in these terms. It isn't that dissimilar to thinking about time as a dimension.

 

However...

 

As far as I can tell in the videos, the audience were not wearing 3D glasses and nobody has made a lenticular that big. This means that in fact the image that was being projected was only 2D (with perspective 3D content). Adding on your extra image mapping 'dimension' only adds up to 3 so it is still arse-gravy for the 2 examples.

 

In my opinion, it can only be billed as 4D if the video is 'different eye image 3D' plus some other enhancement of the experience.

[richb]

I await input from Jason of this parish (from 5d!) with interest!

[dsharp7th]

I ask because I feel that the 4D term is well on its way to becoming the generic PR and/or laymans term for multi plane building projection (both of my links use 4D in their description). As an event organiser, should I be complicit in the adoption of the term to explain things to people when it clearly doesn't sit right with a certain technical mind, as Brian eloquently demonstrates, despite other technicians people happy to justify its use.

 

The best practitioners need something zingy to distinguish their work from an outdoor powerpoint show, but I suspect we'll all soon hear more and more people using the term with little understanding of what they are saying. (what's new there?)

 

Still, little point in trying to enlighten most people on strict use of the term if it involves Euclidean geometry and mind bending representations from the off (those gifs are enthralling). And any projection artist who convincingly makes a building appear to rotate inside it's own mirror image probably deserves their extra 'D'.

[alistermorton]

I ask because I feel that the 4D term is well on its way to becoming the generic PR and/or laymans term

 

In the same way that "random" is the PR/laymans term for "a little bit different or out of the ordinary" or "blatant" has become the term for "clearly" or obviously, as in "He was blatantly wearing a blue shirt, not green as you thought"?

 

 

 

[Andrew Edwards]

Well it seems that the 4D in SXS brief description could actually be argued to be slightly more than marketing drivel. The 4th dimension is time and it is this change in time which is creating movement. Having it look like the shadow from an physical structure is moving, recreating the movement of a light source would simulate a 4D experience. That is if your definition of 4D is spacetime.

[Brian]

...and it is this change in time which is creating movement.

So films at the cinema have been 3D all along?

[Seano]

And any projection artist who convincingly makes a building appear to rotate inside it's own mirror image probably deserves their extra 'D'.

 

Extra two 'D's given that their projection is in fact 2D - regardless of the shape of the surface they're projecting it onto.

[Brian]

So what we're talking about is 2DD?

[indyld]

Well it seems that the 4D in SXS brief description could actually be argued to be slightly more than marketing drivel.

 

Well, some might say that would be an innovation in itself at least. I wouldn't care to comment.

 

I've always thought that if you favour spacetime over the Euclidian, then any show is surely 4D or at least D+1? If it happened over no time at all I'd want my money back.

 

However, it seems as if perhaps the four dimensions may be cited as being width, height, depth and hyperbole where hyperbole is reality bent around a singularity and squared until it makes a headline. :)

[ramdram]

Well, according to Einstein...and you won't need me to remind you about his view; he decided the fourth dimension is time. BUT this fourth dimension only works in one direction ie. you can't go back in time...well not yet anyway, ahem...or if they can in the future then they have kept pretty quite about it else cavemen would have mentioned it...

 

http://science.howstuffworks.com/science-vs-myth/everyday-myths/see-the-fourth-dimension.htm

 

Mind you, Einstein's then views might be pants if we can believe stuff does travel faster than the speed of light...

 

(And, if you are into string theory then it seems having 10 dimensions is an absolute must.)

 

I suspect what really happened to the advertising mob is that they confused 4D with 4G...easily done.