A method for determining a 3D model of an environment using a stationary first 3D recording device (G 1) for generating a first 3D point cloud (P 1) in a first coordinate system, a mobile second 3D recording device (G 2) for generating at least one second 3D point cloud (P 2) in a second coordinate system, and an evaluation unit connectable or connected to both 3D recording devices (G 1, G 2), comprising the steps of: 3D recording of a first section (S 1) of the environment with the first 3D recording device (G 1) from a rest position (L R) of the first 3D recording device (G 1) determined in the first coordinate system to generate the first 3D point cloud (P 1); before or after the 3D recording of the first section (S 1), 3D recording of a second section (S 2) of the environment with the second 3D recording device (G 2) from a recording position (L A) of the second 3D recording device (G 2) determined in the second coordinate system to generate the second 3D point cloud (P 2); after the 3D recording of the second section (S 2), moving the second 3D recording device (G 2) from its recording position (L A) to a parking position (L P) determined in the second coordinate system, or before the 3D recording of the second section (S 2), moving the second 3D recording device (G 2) from a parking position (L P) determined in the second coordinate system to its recording position (L A), wherein in the parking position (L P) the second 3D recording device (G 2) takes a relative position (L rel) determined in the first or second coordinate system (A, B) with respect to the rest position (L R), which the first 3D recording device (G 1) takes both when 3D recording the first section (S 1) of the environment and when the second 3D recording device (G 2) takes the parking position (L P); aligning (12, 15) the second coordinate system with the first coordinate system taking into account the relative position (L rel) and a deviation (ΔL), determined in the same coordinate system (A, B) as the relative position (L rel), between the parking position (L P) determined in the second coordinate system and the rest position (L R) determined in the first coordinate system; after the aligning (12, 15), arranging the second 3D point cloud (P 2) in the first coordinate system; and combining the first and second 3D point clouds (P 1, P 2) in the first coordinate system to form the 3D model in the evaluation unit. 3D recording of a first section (S 1) of the environment with the first 3D recording device (G 1) from a rest position (L R) of the first 3D recording device (G 1) determined in the first coordinate system to generate the first 3D point cloud (P 1); before or after the 3D recording of the first section (S 1), 3D recording of a second section (S 2) of the environment with the second 3D recording device (G 2) from a recording position (L A) of the second 3D recording device (G 2) determined in the second coordinate system to generate the second 3D point cloud (P 2); after the 3D recording of the second section (S 2), moving the second 3D recording device (G 2) from its recording position (L A) to a parking position (L P) determined in the second coordinate system, or before the 3D recording of the second section (S 2), moving the second 3D recording device (G 2) from a parking position (L P) determined in the second coordinate system to its recording position (L A), wherein in the parking position (L P) the second 3D recording device (G 2) takes a relative position (L rel) determined in the first or second coordinate system (A, B) with respect to the rest position (L R), which the first 3D recording device (G 1) takes both when 3D recording the first section (S 1) of the environment and when the second 3D recording device (G 2) takes the parking position (L P); aligning (12, 15) the second coordinate system with the first coordinate system taking into account the relative position (L rel) and a deviation (ΔL), determined in the same coordinate system (A, B) as the relative position (L rel), between the parking position (L P) determined in the second coordinate system and the rest position (L R) determined in the first coordinate system; after the aligning (12, 15), arranging the second 3D point cloud (P 2) in the first coordinate system; and combining the first and second 3D point clouds (P 1, P 2) in the first coordinate system to form the 3D model in the evaluation unit.