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How well you can measure the distance with the help of photos taken on the phone's camera?

asked 2016-09-17 02:10:52 -0500

updated 2016-09-17 02:23:31 -0500

berak gravatar image

How well you can measure the distance with the help of photos taken on the phone's camera? I need to measure the human figure 3 feet, how well it can be done? Ideally, the need to measure the error was no more than 0.1 mm обувь.jpg 4.jpg

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answered 2016-09-17 04:30:12 -0500

pklab gravatar image

Due to nature of the object, accuracy of 0.1mm is non sense. Sincerely there aren't fixed/stable points where you can take so accurate and repeatable measure... this is true even if you would use an ultra accurate calliper!

But you could use a well know reference such as "Regular graphing paper" behind/in contact to your object and take the photo as much as frontal. Finally, count lines between interesting points to get an estimation of distances.

Sure error will be more than 0.1 mm due to the distance between the object and the graphing paper and the angle between the camera and the object.

You could reduce a bit this perspective error using the Camera Calibration Chees Board but, again, expected improvement is non sense

In addiction the camera calibration provides the pix/mm constant but it would require to use the camera and the object from a fixed point.

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And if we know such human foot lengths, that is, the program has to be given a reference point, so really there to make accurate calculations? And what if when photographing use your phone accelerometer that will allow us to select the appropriate angle for photography? So I thought to try to apply the frame silhouette in order to further limit the unnecessary objects in the camera and focus only on foot?

Unicorn gravatar imageUnicorn ( 2016-09-18 01:32:55 -0500 )edit

Sorry but I can't understand your goal.

pklab gravatar imagepklab ( 2016-09-19 06:12:30 -0500 )edit

my friend's shop making custom shoes. And to make the pad under the foot of the customer is necessary to measure these parameters just legs. Clients usually measured not quite right, and so he wanted to make such an application here

Unicorn gravatar imageUnicorn ( 2016-09-19 07:27:22 -0500 )edit

Ok it seems you need of 3D measurement e.g. for the instep I think you need of 3D reconstruction therefore stereo vision... You could use accelerometer to know relative position between frames than try with stereo vision but I won't expect accurate result. Finally I don't know if Huawei P9 dual-cam could be used for stereo vision. Another way you might investigate is to use any pattern light and get profiles from pattern deformation...a bit hard from unknown position

pklab gravatar imagepklab ( 2016-09-19 12:08:51 -0500 )edit

Not every phone has two cameras), so we are planning to do to develop a device with a camera. But I do not know where to start, how to use the library, and in general as far as possible to implement our idea

Unicorn gravatar imageUnicorn ( 2016-09-19 12:56:36 -0500 )edit

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Asked: 2016-09-17 02:10:52 -0500

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Last updated: Sep 17 '16