c# making a coordinate system for a picture

Okay, I have an image in a picture box locating in a panel so it has a scroll bar and its anchored so it maximizes with the form. The image is a map and im trying to make a coordinate system for it, but I have no idea where to start.

The system includes: Degrees, Minutes for North and South, Degrees, Minutes for West and East. The start location (Origin) is in a random location on the image where it would be: 0d 0m North 0d 0m West

I cant really explain but when you move your mouse that tiny little bit that moves it over just that tiny little bit, to the next pixel maybe I dont no, will increment the minutes. After 60 minutes it will restart to 0 and the degrees will go up one.

Where do I start? I can make a certain part of the image the origin and make a formula so it calculates the cordinates on any area of the picture??

 

Code:

Point LocalMousePosition = new Point();
            LocalMousePosition = pictureBox1.PointToClient(Cursor.Position);
            toolStripStatusLabel1.Text = "X=" + LocalMousePosition.X + "," + "Y=" + LocalMousePosition.Y;

This sets it up so that it tells me the location from the top left corner of the map. Is there anyway I can set the origin from the top left corner to a specific coordinate like. x=785 y=1994.

 

Subtract the numbers from the coords:

Code:

toolStripStatusLabel1.Text = "X=" + (LocalMousePosition.X-785) + "," + "Y=" + (LocalMousePosition.Y-1994);

This will give (0,0) for (785,1994)
I guess you know how to get degrees, minutes from that:
Use modulus to find the minutes: min = Math.Abs(x) % 60;
Use division and Math.Floor to find the degrees: deg = Math.Floor(x / 60);

I used Math.Abs on the minutes, because you probably don't want to repeat the sign that will already be in the degrees.

 

Ya thanks, that worked like a charm, only thing now is I'm having a problem drawing a horizontal and vertical line on the map. Say someone selects 630x 450y i want both lines to go through thoughs points??

 

Is that map coords, or mouse coords?
If it is map coords, you will need to add the bias back (785 to x, 1994 to y in your example) before the following will work right:

To draw the vertical line, use
DrawLine(blackPen, x, y-h, x, y+h);
where h is half the line size: h=lineLength/2;
For the horizontal one,
DrawLine(blackPen, x-h, y, x+h, y);
should work.