A method for interactively providing waypoints to a mobile robot for use in the marking of a geometric figure on a ground surface comprising the steps of: i) Selecting a control function on the control unit of said mobile robot accepting manual positioning of said mobile robot at two or more target locations on said ground surface; wherein said mobile robot comprises a position determining device comprising a pointing device with a tip, and adapted for pointing to a target location to be measured, said pointing device being a part of a paint spraying means and being positioned on the rear end of the mobile robot; wherein said pointing device is mounted on said mobile robot such that said tip of said pointing device is visible for the user of said mobile robot when the user is in an upright position; ii) Positioning, manually, or via said control unit, said mobile robot in proximity to a first target location to be marked on said surface, and directing said tip of said pointing device mounted on said mobile device towards said first target location to be marked; iii) Instructing said mobile robot via said control unit to store said first target location as a first waypoint; iv) Repeating steps ii)-iii) to obtain at least a second waypoint; v) Selecting a control function on said control unit of said mobile robot accepting manual selection of a geometric figure for being marked on said ground surface; vi) Instructing said mobile robot via said control unit to compute the best fit for said selected geometric figure on said surface based on said two or more waypoints; vii) Instructing the mobile robot via said control unit to compute waypoint coordinates of said geometric figure for being marked from said best fit position of said geometric figure on said surface; and viii Instructing said mobile robot via said control unit to mark said geometric figure onto said surface. i) Selecting a control function on the control unit of said mobile robot accepting manual positioning of said mobile robot at two or more target locations on said ground surface; wherein said mobile robot comprises a position determining device comprising a pointing device with a tip, and adapted for pointing to a target location to be measured, said pointing device being a part of a paint spraying means and being positioned on the rear end of the mobile robot; wherein said pointing device is mounted on said mobile robot such that said tip of said pointing device is visible for the user of said mobile robot when the user is in an upright position; ii) Positioning, manually, or via said control unit, said mobile robot in proximity to a first target location to be marked on said surface, and directing said tip of said pointing device mounted on said mobile device towards said first target location to be marked; iii) Instructing said mobile robot via said control unit to store said first target location as a first waypoint; iv) Repeating steps ii)-iii) to obtain at least a second waypoint; v) Selecting a control function on said control unit of said mobile robot accepting manual selection of a geometric figure for being marked on said ground surface; vi) Instructing said mobile robot via said control unit to compute the best fit for said selected geometric figure on said surface based on said two or more waypoints; vii) Instructing the mobile robot via said control unit to compute waypoint coordinates of said geometric figure for being marked from said best fit position of said geometric figure on said surface; and viii Instructing said mobile robot via said control unit to mark said geometric figure onto said surface.