Sign up ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Do you know of a formula or function that can calculate the real world height of a satellite image in degrees?

The image is from Google Static Maps and the image uses Mercator projection which makes calculating the height very difficult. I can successfully calculate the width but I don't know of a formula to calculate the height of the satellite image in degrees.

enter image description here
For the above image I know this information:

  • Width= 400px
  • Height= 400px
  • Central mid point is: -32 Lat 151 Long
  • Google's zoom value is 14

This is how I calculate the width which works:

// The reason I use 256 is because in google the whole earth fits inside 256 pixels
// when the zoom value is 0(zoom can be 0 > zoom < 25)
float meshWidthDeg = (imgWidth/256f)*(360f / Math.Pow(2f,zoom));
share|cite|improve this question

2 Answers 2

After a quick look at the Wikipedia entry for the Mercador projection, I believe that for short distances, the horizontal and vertical scales are the same (on a printed map). Scroll down to Formulae for distance. Pixels are usually not square, so you have to allow for that, and it could vary between devices.

There is a comment there that Google uses a variant of the Mercador.

share|cite|improve this answer

map a matrix over the image, and find the actual coordinate points of the grid points of your matrix. fill a second matrix with calculations of the coordinate points with the information of your picture. with two values in every gridpoint you can figure out a matrix of slopes.

make a list of functions using the respective slopes and actual coordinate points.

find the convergence point of these functions. with the convergence point you can construct a pyramidoid from which you can find whatever angle you want.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.