Yes, I've had some very unnatural stretching effects by placing objects too near; even after editing to reduce the horizontal displacement of the captured images.
I saw some fireworks this weekend at around 300m distance and the stereoscopic effect was fairly strong for my unaided vision. It made me think that not too great an inter-axial might do the trick for fireworks at that sort of distance.
I've obtained some more, promising, results with the Logitech C920 webcams for portable use with an old notepad pc. This is not a point and shoot methodology! It requires time at the computer screen to set up and control (including the settings for each camera). But for occasional 3D high interaxial shots, it strikes me as worthwhile experimenting with.
The C920 webcam includes hardware encoders for MPEG-4 AVC, and motion JPEG, taking the processing load away from the pc. Using two webcams, and graphedit.exe,1
I found that my notepad pc and my desktop pc could record MJPG streams in correct synch using the following graph I put together:
The notepad could record Left and Right MJPG at 1280x720p30 or 1920x1080p24 without dropping frames. The desktop pc could manage 1920x1080p30 very comfortably. [There is no monitoring facility with this graph. To correctly aim the cameras prior to recording, I suggest using the software Sterescopic Multiplexor. After running the graph, the saved files -Left.asf and -Right.asf can be renamed so that the next running of the graph doesn't overwrite them. It is likely that the asf files will be out of time alignment by a small whole number of frames. This will be noticeable if playing using Stereoscopic Player. Edit: see footnote 2.
Note that the audio obtained from the camera using this graph may not be of particularly good quality. The graph for the Right file shows another source of pc audio, useful if separate mikes are available.]
I found the MJPG frames showed minimal encoding artifacts. They are simply an individual jpeg image for each frame.
(I tried capturing two MPEG-4 AVC streams, using the following filter in graphedit: GDCL Mpeg-4 Multiplexor
, but there were fairly noticeable encoding artifacts, and the streams were asynchronous.)Angle bracket a bit conspicuous
For about $10, I was able to obtain some 1/4" bolts with UNC thread, washers and nuts (for the tripod socket in each camera), and a length of slotted metal angle bracket. Using different slots in the bracket I could obtain various interaxial distances for the webcam lenses, up to 24" (60cm). With the help of Stereoscopic Multiplexor to view the combined camera output, I aligned by eye. This was close enough to be usable. In fact Vegas Pro doing an automatic adjustment reported nil vertical correction required for a number of my test videos! This was ok for use on a car dashboard, but in public the bracket looked conspicuous.
I found it convenient in public simply to place the webcams on top of the notepad screen, and that way could obtain up to 7.16" (182mm) lens separation. That is about 3 times the mean adult interpupillary distance.
Now that I have the basics in place, I should be able to concentrate on getting some interesting footage with my portable notepad pc and the two webcams. So far I've noticed that even 30fps is slow for road traffic on city streets. During the day, the webcams are producing a blur-free image for each frame, so must be using a short exposure time, but the distance moved by the traffic even in 1/30th second is considerable.
____________1 Graphedit can be useful for these oddball tasks. One site where 64-bit and 32-bit versions can be found is: http://www.videohelp.com/tools/GraphEdit
2 Running two instances of VirtualDub can be good for detecting the number of frames of misalignment between the Left and Right files. The delayed file can then be resaved omitting the required number of frames at the beginning, using VirtualDub set for "Direct stream copy". You should then have Left and Right files that are time aligned within a small fraction of the duration of a frame. Disclaimer: I cannot guarantee use with other pcs will result in C920 webcam electronic shutters coming into close synch with each other.Edited by MLXXX - 9/30/12 at 7:47pm