How to calculate the difference between two data in degrees and the values ​​of geographic longitude in meters?

Question

Java

Recently I ran into the problem of converting geographic coordinates to meters. That is, for example, I can display the distance between one point with geographical coordinates in degrees and another point whose coordinates are given in meters, but I cannot find out the distance in meters between one longitude value and another longitude value, and I cannot yet understand how do it.

Answer 1

If in your question you mean what you wrote, then this is simply impossible geometrically.
A single value of longitude defines a line from pole to pole, called a meridian . Two longitude values ​​define two such lines. These lines are on the surface of the Earth (or a figure modeling it - a geoid or a sphere), so they are not parallel. The distance between these lines, measured along the line of latitude (latitude, parallel), thus varies from maximum at the equator to zero at the poles, where they converge to a point. Here is the distance between the parallels (values ​​of latitude, latitude) along the meridian can be calculated, but not vice versa.
Understand, please, the basic concepts of coordinate systems and projections, this will save you a lot of questions automatically.

Answer 2

Coordinates are conditional points of latitude and longitude on the surface of the ball. They are related to meters and kilometers only when converted to the surface of the ball. It is usually calculated according to the haversine formula. It is described in detail here - gis-lab.info/qa/great-circles.html
At long distances, it can give an error of 20-30 kilometers - the distance from Moscow to Washington, for example.
For more accurate calculations, they use the geoid model - a simplified model of the Earth, but the formulas there are completely different.
PS. I re-read the question again, and here's what I want to say ...
Longitude (meridian) - a circle passing through two poles. The second longitude intersects the first at the points of the poles, where the distance between them will be zero! In other words, the distance between two longitudes (two meridians) is highly dependent on the latitude (parallel) at which this distance is measured.

Answer 3

Take Proj4 (and now version 5), transform it into the desired UTM zone and get the difference in meters. But this is taking into account that you do not have long distances, the zones go at 6 degrees.