Measuring device for three-dimensional scanning of an environment comprising • a base, • a rotating member rotatable relative to the base about an axis of rotation, • a transmission unit with a transmission beam generation area and an exit area arranged on the rotating member and configured to emit transmission beams via the beam exit area in different beam directions relative to the rotating member, wherein the beam directions are defined by directional data of the transmission beams comprising elevation data with respect to a reference plane perpendicular to the axis of rotation and rotational data with respect to a radial line on the reference plane, • a receiver unit with a beam entry area and a beam detecting area arranged on the rotating member and configured to receive returning transmission beams from the beam directions via the beam entry area and to generate distance measurement data relating to emitting and receiving of the transmission beams, • an angle determining unit (13, 14) configured to determine angular data relating to the angular orientation of the rotating member about the axis of rotation relative to the base, • a computing unit configured to derive three-dimensional point cloud data by combining the distance measurement data, the angular data, and stored directional data for the respective transmission beams, • a longitudinal member being fixed to the base and extending over a range including the transmission unit with the beam exit area and the receiver unit with the beam entry area, and • two bearing members being arranged on the longitudinal member and on the rotating member such that the rotating member is rotatable about the axis of rotation, wherein in the direction of the axis of rotation, the transmission unit with the beam exit area and the receiver unit with the beam entry area are located between the two bearing members characterized in that • the longitudinal member extends in a central area of the rotating member along the axis of rotation over the range including the transmission unit with the beam exit area and the receiver unit with the beam entry area. • a base, • a rotating member rotatable relative to the base about an axis of rotation, • a transmission unit with a transmission beam generation area and an exit area arranged on the rotating member and configured to emit transmission beams via the beam exit area in different beam directions relative to the rotating member, wherein the beam directions are defined by directional data of the transmission beams comprising elevation data with respect to a reference plane perpendicular to the axis of rotation and rotational data with respect to a radial line on the reference plane, • a receiver unit with a beam entry area and a beam detecting area arranged on the rotating member and configured to receive returning transmission beams from the beam directions via the beam entry area and to generate distance measurement data relating to emitting and receiving of the transmission beams, • an angle determining unit (13, 14) configured to determine angular data relating to the angular orientation of the rotating member about the axis of rotation relative to the base, • a computing unit configured to derive three-dimensional point cloud data by combining the distance measurement data, the angular data, and stored directional data for the respective transmission beams, • a longitudinal member being fixed to the base and extending over a range including the transmission unit with the beam exit area and the receiver unit with the beam entry area, and • two bearing members being arranged on the longitudinal member and on the rotating member such that the rotating member is rotatable about the axis of rotation, wherein in the direction of the axis of rotation, the transmission unit with the beam exit area and the receiver unit with the beam entry area are located between the two bearing members characterized in that • the longitudinal member extends in a central area of the rotating member along the axis of rotation over the range including the transmission unit with the beam exit area and the receiver unit with the beam entry area.