Angle of elevation using coordinates

Question

I'm currently using an OSM dataset of San Francisco and I want to calculate the angle of elevation of each road segment using x and y coordinates given by this dataset. I used this formula and I get wrong data. the formula:

dLon = (long2 - long1);
y = Math.sin(dLon) * Math.cos(lat2);
x = Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1)
        * Math.cos(lat2) * Math.cos(dLon);

angle = Math.atan2(y, x);

angle_degree = Math.toDegrees(angle);
rt = (angle_degree + 360) % 360;
ang = 360 - rt;

Ps: I converted longitude and altitude coordinates to radians to use this formula.

Have you any other suggestions please?

Answer 1

Where is the z data?

the angle would be asin(z/(x^2+y^2)) with x^2+y^2 == (x1-x2)^2+(y1-y2)^2 expressed in Cartesian co-ordinates. In "Vector geometry" with Add_geometry one can convert and add x,y co-ordinates to the table.

For the z-data you need a raster/vector layer (LIDAR,SRTM) which you can also convert to have x,y co-ordinate pairs.

And there is the elevation/slope/degrees plugin tool