CODEWITHSUNDEEP
androidcameraandroid-camera
J Innovation
J Innovation

Reputation: 13

Getting distance between person and camera

I want to know the distance of person form camera . i am using android motorola tablet.

i am using camera api of android - API Level 14.

i am using following formula:

objectDistnance = ((objectheight(pixel) * focal-length(mm)) / imageheight(pixel);

imageHeight is height of my preview screen;
focal length i am getting from Camera api : 4.42 mm;
object height i am giving as input of person's height in mm : 1620mm

and i want to calculate the distance of person from camera.

by using this formula i am getting wrong distance it is giving me 60mm but actually it is more then 2500mm

so please anyone help me with this am i using correct formula ?

what should i do to get the correct distance of person from camera

Upvotes: 1

Views: 2655

Answers (1)

HashtagMarkus
HashtagMarkus

Reputation: 1661

From here I got the following formula:

distance to object (mm) = focal length (mm) * real height of the object (mm) * image height (pixels)
                          ---------------------------------------------------------------------------
                          object height (pixels) * sensor height (mm)

So it seems you did not include enough reference variables.

Lets asume the following:

Focal Length: 4,42mm
Real Height of object: 1620mm
Image Height: 2048px
Object Height: 1024px
Sensor height: 24mm

4.42mm * 1620mm * 2048px
-----------------------
1024px * 24mm

The Result of this would be 1193 mm Since I don't know all of your variables I could not recalculate your situation.

edit I just checked this formula using my Samsung Galaxy S with the following values:

3.79mm focal length 
100mm real object height
2592px image height
1200px object height on image
4.54mm sensor height

I took a picture from about 200 - 250 mm away (I did not measure the exact distance). The result of this calculation is ~200mm which would fit to this test.

Upvotes: 2

Related Questions