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Old Apr 24, 2007, 7:58 PM   #1
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Hi

First of all I want to mention that I am new in this world.

I am doing a research in road safety that requires taking pictures of roads, especially at the corner of intersections. I need to focus on the objects in the street and have the picture to be mimicking the real eye viewing of that street because my research includes eye movement detecting. Therefore I need the picture to present the street as it seen through the eyes not a camera's lens. I think a wider angle lens could help but I am not sure. I will appreciate it if you tell me how to take this type of picture. Also I am wondering if I am going to present these pictures in a projector, what would be the best way to take these picture, (i.e. panoramic picture can solve this problem). Also can I use my SONY Cyber-shot DSC-P200 in taking these pictures, of course after buying the appropriate lenses?

Thanks
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Old Apr 24, 2007, 8:26 PM   #2
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Your probably best to direct your questions to the person or persons who will be reviewing and approving your work.

What do they think is acceptable?
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Old Apr 24, 2007, 8:38 PM   #3
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Thank you for your replay. To be clear, the research is for psychology and road safety. I already took picture and used it for my first experiment, but it was not wide enough to mimic the real view of the street as you see it through your eye. And because I am going to use eye tracker while presenting these photo in m Lab, I need them to mimic reality. Therefore I want to buy the right lenses to take the right picture for my study.
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Old Apr 24, 2007, 9:51 PM   #4
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From your description of your lab setup, my guess is that you will need to take several pictures and stitch them together into a panorama. A lens with a wide enough angle to present as equivalent to human vision (including peripheral, if I am reading you correctly) would be a fisheye with considerable distortion.

If this is the case, check in the panorama forum here for some good information on techniques and programs to create panoramas.

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Old Apr 25, 2007, 12:59 PM   #5
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Simulating a driver's view is a fairly complex issue in and of itself. Having an entire IMAX system and theaterat your disposal would be handy :lol:.

The basics, the eyes have nearly a 180 degree field of view of which 140 degrees is stereoscopic. I think, therefore yourstarting target should be around 140 which will require panoramic stitching. The single shot horizontal fields of view for various focal lenses is as follows, stated as 35mm equivalents:

24mm=74, 28mm=66, 35mm=54,50mm=40

From this you canestimate the number of individual shots needed for the desired field of view. The 38mm wide angle of your Sony will be about 50 degrees. The wide angle aux. lens for your Sony will yield about 27mm equiv.

The stitching can be done in software and assuggest earlier the panoramic forum here http://forums.steves-digicams.com/fo...orum.php?id=69would be useful.

It might be worth considering cameras that have built in panoramic software since you will actually be in the roadway when taking the pictures. The advantage is that they offer in-camera aiming guides besides actually stitching the photos. The Kodak C875, Z885, V1002 and P712 can capture 150 degrees within the 3 shot limit of their software and the Kodak V705 can capture 150 in two shots, 180 in three shots. Othermakers probably have some camera with equivalent capabilities. Hopefully others willfurnish those alternatives.

You also need to account for field of view in your presentation to your subjects. If you're using a projected image you can somewhat control that by adjusting the subjects distance to the screen.
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Old Apr 25, 2007, 8:29 PM   #6
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Very wide panoramas with strong horizontal features near the top or bottom always look funny. Regardless of projection. About the only way to avoid that is to stand in exactly the middle of an intersection or the middle of the road.

But try it and find out for sure. There are some good tips in the forum a.c. mentioned and links to simple stitiching software.
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Old Apr 26, 2007, 10:57 AM   #7
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fkh1975,I am "no expert" in this. but as i was reading your requirement where you have repeated asking for " mimicking the real eye view".I think you are asking for " angle of view" in other word how much a person can see at the given time. If that is your requirment then your focal length is "50 mm".But that is anlge of vision of a driver in "static state."But since we are dealing with "speed ", the vision become more telescopic,means angle of vision become more narrower. So you need to increase the the focal length.If this much be any help to you
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Old Apr 27, 2007, 1:14 PM   #8
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mcliu's details are wrong but he states a valid consideration.

The general definition of a "normal" lens is one that has a 50[suP]o[/suP] diagonal
field of view which is actually 43mm on a 35mm camera. Custom however has
defined "normal" for 35mm camera as 50mm which produces a 46[suP]o[/suP] diagonal FOV.
The numbers in my chart are for the horizontal FOV since that seems more
applicable than the diagonal FOV. I didn't compute the horizontal FOV for a
43mm lens since I didn't consider it relevant. "Normal" is simply an
approximation of the high resolution central vision. That still depends on
the definition of "high resolution" as there is an even narrower FOV that
delivers higher resolution than average over 50[suP]o[/suP].

Our brain employs "digital zoom". As speed increases the brain discards
information that is not actionable, effectively narrowing the field of view.
Two factors involved, as speed increases we have to make our decisions based on information that is further away plus the information from the peripheral is arriving at a rate faster than it can be processed. Emulating a driver's view with still photos will be challenging.

If the point is to find out how "actionable" items are found in a visually cluttered field the presentation will be as important as the photos. To elicit a "search" the presentation must be wider than the central vision, there's no need to search if one can take in the whole scene at once. It might also be necessary t give the subject a task such as "How quick can you click on the stop sign?" while you monitor the eye movements to accomplish the task.A driver's actual task is to find all actionable items and then prioritize them.



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Old Apr 27, 2007, 8:12 PM   #9
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I think a.c. has it basically right, though I would quible about the size of the high resolution section of human vision: I think it is closer to what a 100 to 150 mm lens (35mm) would cover.

The important point is that no photo will mimic the view of the human eye. In particular, none will deal with the "on demand digital zoom".

fkh1975: take a look at how images are presented in simulators, that is probably what you want to do. Close to the viewer and wrapping around. Three to five images with frames between them so you don't have to deal with stitching and the distortion that comes from that.
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Old Apr 28, 2007, 2:57 AM   #10
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ac.smith wrote:
Quote:
mcliu's details are wrong but he states a valid consideration.

The general definition of a "normal" lens is one that has a 50[suP]o[/suP] diagonal
field of view which is actually 43mm on a 35mm camera.* Custom however has
defined "normal" for 35mm camera as 50mm which produces a 46[suP]o[/suP] diagonal FOV.
The numbers in my chart are for the horizontal FOV since that seems more
applicable than the diagonal FOV.* I didn't compute the horizontal FOV for a
43mm lens since I didn't consider it relevant.* "Normal" is simply an
approximation of the high resolution central vision.* That still depends on
the definition of "high resolution" as there is an even narrower FOV that
delivers higher resolution than average over 50[suP]o[/suP].

Our brain employs "digital zoom".* As speed increases the brain discards
information that is not actionable, effectively narrowing the field of view.
Two factors involved, as speed increases we have to make our decisions based on information that is further away plus the information from the peripheral is arriving at a rate faster than it can be processed.* Emulating a driver's view with still photos will be challenging.

If the point is to find out how "actionable" items are found in a visually cluttered field the presentation will be as important as the photos.* To elicit a "search" the presentation must be wider than the central vision, there's no need to search if one can take in the whole scene at once.* It might also be necessary t give the subject a task such as "How quick can you click on the stop sign?" while you monitor the eye movements to accomplish the task.***A driver's actual task is to find all actionable items and then prioritize them.


*
Thanks for rectifying me.But one thing remains valid that seeing the thing in static state is entirely different from when one is in motion.As Bildrew too has pointed out rightly "no photo can mimic the eye".Quite an statment.I have thought about it later,by the time it was too late for me.
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