# Equation to measure meters from pictures

12 views (last 30 days)
Abdussalam Elhanashi on 21 Dec 2020
Answered: Image Analyst on 24 Dec 2020
Hi,
I am measuring the distance between the centroid of bounding boxes for detected objects in pixels in the images .I am looking for an equation which convert the measurment in pixels into meters .
Best
Matt Gaidica on 21 Dec 2020
Edited: Matt Gaidica on 21 Dec 2020
You're going to need a reference in your frame—do you have that? (e.g., a ruler) Once you have that, you have some ratio of pixels/meters, and you divide your object pixel distances by that to get your answer.

Rishabh Mishra on 24 Dec 2020
Hi,
To find distance between 2 points, you require their co-ordinates. Assuming co-ordinates for 2 points are stored in arrays x & y respectively. The distance ‘D’ between these 2 points is given by,
x= [1 2 3];
y= [3 4 5];
D = norm(x-y);
The distance value so obtained has units as pixels. Convert pixels into meters using the conversion value given below:
1 pixel = 0.0002645833 m
Hope this helps.
Image Analyst on 24 Dec 2020
Where did you get that number?

Image Analyst on 24 Dec 2020
See my spatial calibration demo. It will show you how you can get the meters per pixel, or whatever real world units you're using.

### Categories

Find more on Feature Detection and Extraction in Help Center and File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!