Transforming between image coordinates and world coordinates
SharpMap has built-in functions to help you transform between image and world coordinates.
When the user clicks the map at a given pixel (x,y), you can translate this world coordinates using the ImageToWorld method:
SharpMap.Geometries.Point p = myMap.ImageToWorld(new System.Drawing.PointF(x, y));
Please note that the value is calculated based on the current zoom and center-values of the myMap Map object.
If you want to do the opposite transformation, use WorldToImage:
System.Drawing.PointF p = myMap.WorldToImage(new SharpMap.Geometries.Point(34.225, 175.432));