C#: how to draw a point(x, y) based on azimuth and altitude angles

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I'm not sure if this is the right place to ask this question, if not I apologize.
I have two variables of type double, let's say with the following values:

C#

double azimuth = 93.7221;
double altitude = 14.3398;

I know how to locate the point manually, with pencil and paper. I draw a circle on the paper, and from North I rotate clockwise 93º (azimuth angle) and from this point I go towards the center of the circle up to 14º (altitude angle).
But I have no idea how to turn these two angles into a single x,y point.

What I have tried:

I've been searching math and astronomy websites for over a week to see if I can find any equations, but without success.

Posted 19-Oct-21 0:06am

Lazie Wouters

Updated 19-Oct-21 2:35am

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3 solutions

Solution 1

Just write the same logic that you used for pencil and paper in C#. ;-)

Perhaps, you can use the APIs from OpenStreetMap? I'm afraid you would need to write the logic yourself — if this is not already available in one of the Physics/Astronomy SDKs for the .NET.

Here are some SDKs that I guess would help (just for inspiration, though):
MKMapView Class (MapKit) | Microsoft Docs[^]
Touch and Go - Exploring Spherical Coordinates on Windows Phone | Microsoft Docs[^]
delphi - How do I calculate the Azimuth (angle to north) between two WGS84 coordinates - Stack Overflow[^] (Read this; how they did it in the language, and then reverse engineer it.)

Posted 19-Oct-21 0:34am

Afzaal Ahmad Zeeshan

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Lazie Wouters 19-Oct-21 8:37am

Thank you very much Afzaal, I started reading and I'm finding a lot of interesting stuff. In the meantime BillWoodruff posted another solution which I managed to implement. But I will continue reading the material you indicated because I saw that there are many things there that I can take advantage of.

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BillWoodruff · Accepted Answer · 2021-10-19T01:53:00

This should get you started; "altitude angle to point" and final point is left for you to calculate.

Assuming a circle of radius #radius where rotation is clockwise: i.e., North == #0, East == #90; South == #180, West == #270, with its center 0,0, and bounding-box top left at -#radius, -#radius:

from code i use now:

// using System Drawing
public static readonly double Pi = Math.PI;
public static readonly double RadFactor = Pi / 180.0;
public static readonly double DegFactor = 180.0 / Pi;

public static double DegreeToRadSin(double degree)
{
    return Math.Sin(RadFactor * degree);
}

public static double DegreeToRadCos(double degree)
{
    return Math.Cos(RadFactor * degree);
}

public static PointF DblXYToPointF(double dx, double dy)
{
    return new PointF((float) dx, (float) dy);
}

The location of the azimuth point on the circumference is given by:

C#

int radius = 100;
double degrees = 93.7221d;
PointF p = DblXYToPointF(DegreeToRadSin(degrees) * radius, DegreeToRadCos(degrees) * radius);

// result: X: 99.99206 Y: -1.26026893

Lazie Wouters · Accepted Answer · 2021-10-19T02:35:00

C#

int radius = 100;
double azimuthDegrees = double.Parse(args[1], CultureInfo.InvariantCulture);
PointF p1 = DblXYToPointF(DegreeToRadSin(azimuthDegrees) * radius, DegreeToRadCos(azimuthDegrees) * radius);

double altitudeDegrees = double.Parse(args[2], CultureInfo.InvariantCulture);
PointF p2 = DblXYToPointF(DegreeToRadSin(altitudeDegrees) * radius, DegreeToRadCos(altitudeDegrees) * radius);
            
PointF p3 = new PointF();
p3.X = p2.Y;
p3.Y = p1.Y;

MessageBox.Show("p1 + "\n " + p2 + "\n " + p3);

Output:
p1: {X=95,09093, Y=30,94699}
p2: {X=73,58713, Y=67,71214)
p3: {X=67,71214, Y=30,94699} This is the final x,y location, in this case the position of the sun right now here at my latitude, longitude and time. As I said before, I compared it with what is being shown on the SunCalc website and the result obtained is very consistent with the information there.

Thank you BillWoodruff

C#: how to draw a point(x, y) based on azimuth and altitude angles

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