How to measure height width and distance of object using camera

Question

I referred lot many links but still I am not able to get any point from that I can start my development  I want to measure my image height  width and distance using camera  I found this app   I want to make this type of application not exactly same but quite same but for my requirement I want to measure my image height  width and distance using camera   Can anyone give me suggest me the right way or any example so that I can get more idea about this requirement   I tried this     http   android-er blogspot in 2012 04 gets-distances-from-camera-to-focus html

User · Answer

If you think about it  a body XRay scan  at the medical center  too needs this kind of measurement for estimating size of tumors  So they place a 1 Dollar Coin on the body  to do a comparative measurement    Even newspaper is printed with some marks on the corners   You need a reference to measure  May be you can get your person to wear a cap which has a few bright green circles  Once you recognize the size of the circle you can comparatively measure the remaining   Or you can create a transparent 1 inch circle which will superimpose on the face  move the camera toward away the face  aim your superimposed circle on that bright green circle on the cap  Then on your photo will be as per scale

User · Answer

For measuring distances with a single camera  you need to know some numbers  To measure height of something  say a chair  the only thing you have is the the size of it in the camera  which is in pixels  and can be converted to inches using screen size   that is all  The chance of measuring the height and width is using a reference  say a 6 foot tall person standing next to the chair   This way you can work out in reverse using say a 10 foot tall object  using its size as appearing in the camera  you can work out the size of things at the same distance  on a surface that is not flat  even ensuring that they are at the same distance is a challenge   So using the camera and just the camera  it is not possible  You need to know distance somehow  or need a reference   If you are using the application to measure height of items you know the location of  then using GPS  you can find distance  and rest is math   I have found some links using Google  they may help    http   forestjohnson blogspot com 2010 01 how-to-measure-size-of-object-using html http   gigaom com mobile how to measure   http   www iphonelife com blog 5 cameasure-use-your-camera-measure-size-or-distance   They may help you to find out what other information is needed other than what the camera can provide  so that you can think about your application as well regarding what can be done and what are the limitations   One way is using multiple cameras  and that can be compensated using multiple pictures taken a known distance away  So the application can ask the user to take multiple images  track the distance using GPS  and probably it can work   See these links as well    http   iopscience iop org 1742-6596 48 1 074 pdf 1742-6596 48 1 074 pdf http   www optical-metrology-centre com Downloads Papers Photogrammetric 20Record 201994 20Automated 203-D 20measurement pdf

User · Answer

If you know the viewport angle of the camera  you can use the height in pixels to determine the angle from the top to bottom of the object    Then  using the distance and arctangent calculate the height   height   arctan angle    distance   To find the viewport angle  point the camera at something which is of known height  and make it exactly fill the screen   For example  point it at a ruler  and make it just far enough away that you can only barely see the ends of the ruler   Measure the distance from the camera  and then your total viewport angle is  viewportAngle   tan ruler length   distance    Then  suppose your camera is 480px tall  cheap webcam   and the view angle is 20     If you have an object onscreen which is 240px tall  then its angle is 10    If you know it s 2 feet away  you would say 2 feet   arctan 10       4 1 inches tall     I think    it s 2am so this may be a little off

User · Answer

I think I know what you are asking for  Here is what you can do   first get the height of the person say h meters     if you can calculate the height of the camera from ground  using height if the person i e  h  and get angles A and B using gyroscope or something from android then you can calculate the height of the object using the above formula   Isn t this what you were looking for     let me know if you need any explanation

User · Answer

You can t   You would have to know    How far is the object  you can know your location from GPS   but the object s location   What is the focal length of the camera   Maybe  just maybe if the object was optically tagged with for example a QR code  and you have a code-to-loc map

User · Answer

First of all i will say Nice Thaught to develop such app   Now i am not sure about it  but if you can able to get the face-detection like thing for any object in android camera so with help of that you can achieve that things   Well i am not sure about it but still have give some view so you can get idea of it   All the Best

[android] How to measure height, width and distance of object using camera?

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