Surveying subsystem comprising a camera module and a control and evaluation unit, wherein the surveying subsystem is adapted to be used as part of a surveying system that is adapted to determine positions of a position measuring resource, • the camera module comprising at least two cameras for capturing images, wherein a first of the at least two cameras is designed to capture first images with a lower image resolutions compared to second images capturable with a second of the at least two cameras, • the control and evaluation unit having stored a program with program code so as to control and execute a spatial representation generation functionality in which - when moving along a path through a surrounding - □ a first series of images of the surrounding is captured with the first camera, the first series comprising an amount of images captured with different poses of the first camera, the poses representing respective positions and orientations of the first camera, and a second series of images of the surrounding is captured in parallel with the second camera, and □ a SLAM-evaluation with a defined algorithm using only the first series of images is performed, wherein a plurality of respectively corresponding image points are identified in each of several sub-groups of images of the first series of images and, based on resection and forward intersection using the plurality of respectively corresponding image points, • a reference point field is built up comprising a plurality of reference points of the surrounding, wherein coordinates of the reference points are derived, and • the poses for the images are determined, thus providing for a faster data processing within the SLAM-evaluation compared to processing data generated by capturing images with the second camera, characterised in that the control and evaluation unit is configured so that the spatial representation generation functionality is controlled and executed in such a way that based on the determined poses a point cloud - forming a dense point cloud - comprising 3D-positions of points of the surrounding is computed as the spatial representation by forward intersection using images of the second series of images. • the camera module comprising at least two cameras for capturing images, wherein a first of the at least two cameras is designed to capture first images with a lower image resolutions compared to second images capturable with a second of the at least two cameras, • the control and evaluation unit having stored a program with program code so as to control and execute a spatial representation generation functionality in which - when moving along a path through a surrounding - □ a first series of images of the surrounding is captured with the first camera, the first series comprising an amount of images captured with different poses of the first camera, the poses representing respective positions and orientations of the first camera, and a second series of images of the surrounding is captured in parallel with the second camera, and □ a SLAM-evaluation with a defined algorithm using only the first series of images is performed, wherein a plurality of respectively corresponding image points are identified in each of several sub-groups of images of the first series of images and, based on resection and forward intersection using the plurality of respectively corresponding image points, • a reference point field is built up comprising a plurality of reference points of the surrounding, wherein coordinates of the reference points are derived, and • the poses for the images are determined, thus providing for a faster data processing within the SLAM-evaluation compared to processing data generated by capturing images with the second camera, characterised in that the control and evaluation unit is configured so that the spatial representation generation functionality is controlled and executed in such a way that based on the determined poses a point cloud - forming a dense point cloud - comprising 3D-positions of points of the surrounding is computed as the spatial representation by forward intersection using images of the second series of images. □ a first series of images of the surrounding is captured with the first camera, the first series comprising an amount of images captured with different poses of the first camera, the poses representing respective positions and orientations of the first camera, and a second series of images of the surrounding is captured in parallel with the second camera, and □ a SLAM-evaluation with a defined algorithm using only the first series of images is performed, wherein a plurality of respectively corresponding image points are identified in each of several sub-groups of images of the first series of images and, based on resection and forward intersection using the plurality of respectively corresponding image points, • a reference point field is built up comprising a plurality of reference points of the surrounding, wherein coordinates of the reference points are derived, and • the poses for the images are determined, thus providing for a faster data processing within the SLAM-evaluation compared to processing data generated by capturing images with the second camera, • a reference point field is built up comprising a plurality of reference points of the surrounding, wherein coordinates of the reference points are derived, and • the poses for the images are determined,