3D seems to be all the rage this moment. More movies, more 3D capable theatres, more games, and the first 3D capable television …
So it is definitely a good project subject.
There are a lot of different aspects to 3D vision. All our club members got involved in searching the web and other publications and we got an appointment with Mr. Song at s415 in the SCAET building. I put a summary of my understanding of what I found on the web and heard from Mr. Song in an email to the rest of the group. An email I copied lower down the blog.
My own particular interest goes to ‘stereoscopy’, which basically is dedicating a separate image to each eye, taken with cameras separated at approximately eye distance between left and right eye. Blame it on my ViewMaster having being one of my favourite possessions as a kid.
I firmly believe that combining new technologies (better monitors, cameras, …) with older technology (optical) can still be worth our while.
Therefore I started experimenting with two web cams used simultaneously, creating two images on a monitor. The challenge is to create an optical system that allows you to look with one eye at the one picture, and the other at the other picture. I tried this with mirrors but haven’t been able so far to make something well enough aligned and stable enough to be used with real success.
The promise of a system like this is that the optical system is independent of the picture generation. So as better material becomes available (monitor resolution and size, camera resolution, remote controlled moving cameras, …) what you see gets better with the same optical set up.
Apart from this I also tried out polarized glasses in front of a projector and wearing polarized glasses. This did not work. I found out on the internet why not. Most projection screens mess up the polarization. It takes a special screen to ot mess up the polarization.
All great fun.
Chris
Dec 16th, 2009
3D Vision
10/27/2009
Meeting with Mr. Song, at Sheridan, S415
Mr. Song gave examples of different techniques:
1. stereoscopic images (example ViewMaster, late 19th century cards
with two pictures (left eye/right eye…))
Pros: simple, cheap;
Cons: no moving images, can only be viewed by one viewer;
2. holograms – used to be monochromatic, now full colour and high
resolution
Pros: high resolution, now in full colour, no special glasses
needed;
Cons: needs external light source on it, expensive and complicated
to produce;
3. multiple images broken apart and arranged in lines to compose a
picture seen through special screen. This technique is used in many
different ways:
a. printed material with plastic grooved lens (parallel lines)
attached to it (example of dog on notebook cover)(static image);
Pros: simple, cheap, no special glasses needed;
Cons: one viewer at a time, limited viewing angle;
b. plastic grooved lens in front of iPod (moving image, animation)
(example shown on Mr. Song’s iPod), no gap between iPod screen and
lens;
Pros: relatively simple and cheap material, no special glasses
needed;
Cons: limited viewing angle, one viewer at a time, lowered
resolution
c. sophisticated bigger lenses attached to computer monitors/TVs and
showing more than two views, with gap between screen and lens;;
Pros: wider viewing angle, no special glasses needed, more than one
viewer;
Cons: expensive screens, expensive and complicated production with
multiple cameras;
4. projected images with different colour filters or polarization
filters for each eye or synchronized shutter techniques by which the
viewer sees alternating images in rapid succession;
Pros: can be seen by many viewers simultaneously, great for special
effects;
Cons: coloured lenses do not allow for normal colours;
polarized lenses mean loss in luminosity;
Some of the points to note:
1. 3D content production is greatly helped by taking into account how
the human brain perceives 3D: changed focus (depth of field) and size
for different distances, shadows, straight lines seperating for
instance walls, ceilings and floors (perspective clues) …
2. Because most of these techniques are based on two or more images
being shown in the same space and in the same time as we perceive the
final composed image, resolution is typically divided by the number of
images shown simultaneously and refresh frequency needs to be a
multiple of the frequency typically used for non 3D imaging. For
instance the iPhone has a resolution of 320 x 480, which gets reduced
to 160 x 480 (no vertical duplication of image).
3. Several different aspects of 3D vision are used either seperately
or combined: the different viewpoint of left and right eye and the
different views a viewer expects when he/she moves. This also opens up
the possibility of simulated 3D where viewer position is tracked to
show different images on the screen (for example through the use of
sensors as found in the Wii controller or the small sensors Mr. Song
showed us).
Conclusion:
Most of the discussed techniques require substantial resources. The
cheapest to further experiment with may well be stereoscopic vision
(dual image) and simulated 3D (Wii controller).
Chris Rogiers – 10/28/2009
