Le 16-04-03 04:18, Stephen a écrit :
> On 4/3/2016 7:54 AM, Thomas de Groot wrote:
>>
>> I may be missing something here, but is animation not very easy? just
>> rotate the inner cylinder. Essentially, the whole structure consists of
>> two moving semitransparent, superposed, image_maps.
>>
>>
>
> Probably not. But it is mumble, mumble years since I have seen one and
> was not sure how the effect was created. I thought that the glass
> cylinders might have been moulded to give local lenses on the inside.
>
> Will the illusion work with computer graphics using planer images?
> What sort of masking is needed for the images and what frame rate to
> use? These questions I will need to find an answer to.
> I think that this might distract me from Elite Dangerous, for a while. :-)
>

The inner, rotating, cylinder have transparent and diffuse areas.
The transparent areas can be coloured, as can the diffuse areas.
The light used is usualy a standard light bulb. If the distance between 
the inner and outer cylinders is small, a frosted bulb is used, and a 
clear one if the distance is large. This is to provide softer shading.

It can easily be done with a computer using planar image in several ways.
You can have the shading image with no_image set between the light and 
the image.
You can use back side illumination that replicate the actual device.
You can use a blurred image that is to be layered with the base image.
There are probably other ways to acheive the same effect.

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