This method is mainly used to move objects on the screen. The originalLocation is the current position of an object.
We provide the current location of the object in world coordinates and the place on the screen to which we want to move the object, so this API return the new position in world coordinate that can be assigned to the object in order to move it to the desired screen position. There is no single world coordinate of screen position. This is a vector with infinite points. The point returned is the closest to the given originalLocation.
If you need a point on an object that is picked on the screen coordinate you can use the PickSingleObject method of TxGraphicViewer class. The returned data gives the object and the location.