How get distance in degrees to calculate buffers in athena? - coordinates

Question

Athena only allows to calculate the distance of the buffer in decimal degrees but this value varies with respect to the latitude in the globe, tate to obtain a distance according to the following formula but it is not consistent in Mexico.
Athena function like this : ST_Buffer(geometry, double)
Athena geospatial functions
So, is posible obtain the corresponding distance in decimal degrees over a custom point in map , ex : get the decimal degree for point x, y like that distance in meters is 300 mts
Currently I use the following formula to approximate the decimal degrees but some buffers are quite horrible although it meets the minimum required
SELECT
ST_Buffer(ST_GeometryFromText( shape_wkt) ,
abs(5000.0 * 360.0 / (2.0 * pi() * cos( latitud )* 6400000.0) ) ) AS
dinamic_buffer_5000
5000 is buffer in meters
6400000.0 earth radius in meters
Some useffull questions :
gps-coordinates-in-degrees-to-calculate-distances
Calculate distance in meters using results in degrees
calculating-latitude-longitude-x-miles-from-point

Answer 1

A possible alternative is the following
To obtain the decimal degrees relative to a point one could:
Generate a second point at a distance d for this you would have to implement this formula, where the bearing does not matter
With this second point calculate the distance in Athena that will return the distance in decimal degrees, as input for the buffer function.
As an approximate is good alternative
Now how implement the second point ?....Here is the formula
I will try to convert to SQL code if can :
After a test I realize that even with the difference of distance it is not possible to obtain the buffer in an optimal way.
In this case the distance to the lower point was 300 meters, after obtaining the distance in decimal degrees with Athena an oblate shape is obtained, it changes the degree of inclination of the point by 90 degrees but it only generates a slightly larger shape.
Destination point given distance and bearing from start point
Source code (zory im edit for test my sql ):
destinationPoint(distance, bearing, radius=6371e3) {
// sinφ2 = sinφ1⋅cosδ + cosφ1⋅sinδ⋅cosθ
// tanΔλ = sinθ⋅sinδ⋅cosφ1 / cosδ−sinφ1⋅sinφ2
// see mathforum.org/library/drmath/view/52049.html for derivation
const dist_ang = distance / radius; // angular distance in radians
const angulo = Number(bearing).toRadians();
const rad_lat = this.lat.toRadians();
const rad_lon = this.lon.toRadians();
console.log("distance", distance);
console.log("radius", radius);
console.log("angular distance in radians", dist_ang);
console.log("bearing", Number(bearing));
console.log("bearing angulo ", angulo );
console.log("lat.toRadians", rad_lat);
console.log("lon.toRadians", rad_lon);
console.log("lon",this.lon);
console.log("lat",this.lat);
const sinφ2 = Math.sin(rad_lat) * Math.cos(dist_ang) + Math.cos(rad_lat) * Math.sin(dist_ang) * Math.cos(angulo);
const φ2 = Math.asin(sinφ2); //lat
console.log("φ2",φ2); //lat
console.log("sinφ2",sinφ2);
const y = Math.sin(angulo) * Math.sin(dist_ang) * Math.cos(rad_lat);
const x = Math.cos(dist_ang) - Math.sin(rad_lat) * sinφ2;
console.log("y",y);
console.log("x",x);
const λ2 = rad_lon + Math.atan2(y, x); //lon
console.log("λ2",λ2);
const lat = φ2.toDegrees();//lat
const lon = λ2.toDegrees();//lon
console.log("lon2",lon);
console.log("lat2",lat);
return new LatLonSpherical(lat, lon);
}