Determination of the transverse width and distance of an object with a smartphone camera

TL;DR

This paper presents a method for using a smartphone camera to determine both the transverse width and distance of an object by capturing images from two different positions, leveraging known camera parameters and simple geometric principles.

Contribution

It introduces a novel approach to measure object size and distance using only a smartphone camera and two photographs taken from different positions.

Findings

Accurately determines object width and distance with smartphone images.

Requires only two photographs and known camera parameters.

Provides a practical method for educational and experimental purposes.

Abstract

A smartphone is a powerful learning aid in the hands of a large section of students around the world. The camera of the phone can be used for several learning purposes apart from its obvious purpose of photographing. If the focal length of the lens of the camera can be determined, several experiments in optics can be performed with it. In some recent works, the method of determination of the focal length has been discussed. When a real image of an object is formed by a lens of known focal length, one can determine either the distance or the transverse magnification of the object if the other is known. In this work we have shown that we can determine both the transverse size and the distance of an object, by photographing it from two positions, separated by a distance along the line of sight of the camera.