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estimating real dimensions from images

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 akm5
(@akm5)
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Joined: 17 years ago
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Topic starter  

Hi,
has anyone come across any work being doen on this field - i.e. determining actual dimension measurments from available images?
Say we have a CCTV recording, from it, can we determine a person's height?

thanks ,
akm


   
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(@bithead)
Noble Member
Joined: 20 years ago
Posts: 1206
 

That technology really started in accident re-creation software and has migrated to other areas. It is all based on a known in the image and then working from there.


   
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 akm5
(@akm5)
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Joined: 17 years ago
Posts: 6
Topic starter  

hi,
could you tell me whats it called - more importantly, what terms should i search for to get some literature on the subject.
thanks,
akm


   
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(@larrydaniel)
Reputable Member
Joined: 17 years ago
Posts: 229
 

Crime Vision Software

Check out this link. This is what I use.


   
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(@ck_425)
New Member
Joined: 17 years ago
Posts: 3
 

hi,
could you tell me whats it called - more importantly, what terms should i search for to get some literature on the subject.
thanks,
akm

Search for "Photogrammetry"


   
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 akm5
(@akm5)
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Joined: 17 years ago
Posts: 6
Topic starter  

Hi, photogrametery is more of converting from 2D to 3D using certain scale transformations. Photogrametry does not necessarily involve any actual scales.


   
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(@ck_425)
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Joined: 17 years ago
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Relating to Forensic Image Analysis (and quoted from SWGIT guidelines)

“Photogrammetry is the art, science, and technology of obtaining reliable information about physical objects and the environment through the processes of recording, measuring, and interpreting photographic images and patterns of electromagnetic radiant energy and other phenomena.” [from “The Manual of Photogrammetry, 4th Edition, 1980, ASPRS]. In forensic applications, photogrammetry (sometimes called “mensuration”) most commonly is used to extract dimensional information from images, such as the height of subjects depicted in surveillance images and accident scene reconstruction. Other forensic photogrammetric applications include visibility and spectral analyses.


   
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 akm5
(@akm5)
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Joined: 17 years ago
Posts: 6
Topic starter  

Hi guys,
first of all, thanks to Larry for guiding me to the crime vision software. That is exactly the kind of thing I had in mind.
Secondly, regarding photogrametry, its still coordinate transformation from 2D to 3D and any actual mensuration have to take the path similar to that used in the crimevision software. Say you have the image of a car, you would never know if its a model car or an actual car from doing a photogrametric transformaion of the image - though you will get the precise contours and depth perception. Instead, if there is something to compare the scale in the same image - say a penny - then you can get an idea about the measurments from photogrametry.
Also, from a single isolated image, without any data about the camera's dimensions, focal length etc, a photogrametric reconstruction would not be possible from what I know - or at least is very difficult and inefficient.

Thanks,
akm


   
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