Method for Registering a Total Station in the Reference System of a CAD Model

Abstract

A method for registering a total station, which is deployed in a measurement environment with one or more objects, in the reference system of a computer-aided design (CAD) model, which images the one or more objects of the measurement environment, includes registering the total station by a control device.

Claims

1.-4. (canceled)

5. A method for registering a total station (10), which is deployed in a measurement environment (11) with one or more objects (14, 15, 16, 17, 18), in a reference system (24) of a computer-aided design (CAD) model (25), which images the one or more objects (14, 15, 16, 17, 18) of the measurement environment (11), by a control device (13), comprising the steps of: selecting three surfaces (F.sub.1, F.sub.2, F.sub.3) in the CAD model (25), wherein respective normal vectors ({right arrow over (N)}.sub.1, {right arrow over (N)}.sub.2, {right arrow over (N)}.sub.3) of the three surfaces (F.sub.1, F.sub.2, F.sub.3) span a three-dimensional space; determining a first plane equation for a first plane (E.sub.1), which comprises a first surface (F.sub.1) of the three surfaces (F.sub.1, F.sub.2, F.sub.3), a second plane equation for a second plane (E.sub.2), which comprises a second surface (F.sub.2) of the three surfaces (F.sub.1, F.sub.2, F.sub.3), and a third plane equation for a third plane (E.sub.3), which comprises a third surface (F.sub.3) of the three surfaces (F.sub.1, F.sub.2, F.sub.3), in the reference system (24) of the CAD model (25) by the control device (13); aligning the total station (10) in the measurement environment (11) on a point of intersection (S) of the first plane (E.sub.1), second plane (E.sub.2) and third plane (E.sub.3) in the CAD model (25), wherein the alignment of the total station (10) is defined as a start pose by the control device (13); rotating the total station (10) about an axis of rotation (28) of the start pose and carrying out N, N ∈ , different measurements during the rotation of the total station (10), wherein, in each of the N different measurements, a horizontal angle is measured by a first angle measuring unit (21), a vertical angle is measured by a second angle measuring unit (22) and a distance is measured by a distance measuring unit (23) of the total station (10); storing N different measured points (M.sub.1-M.sub.19) with measured coordinates, wherein the measured coordinates comprise the horizontal angle, the vertical angle and the distance; assigning K of the N, K≤N, different measured points to the first plane (E.sub.1), to the second plane (E.sub.2) or to the third plane (E.sub.3), wherein measured points assigned to the first plane (E.sub.1) are defined as first measured points (A.sub.1), measured points assigned to the second plane (E.sub.2) are defined as second measured points (A.sub.2) and measured points assigned to the third plane (E.sub.3) are defined as third measured points (A.sub.3) by the control device (13); determining a first function equation for the first measured points (A.sub.1), a second function equation for the second measured points (A.sub.2) and a third function equation for the third measured points (A.sub.3) in the reference system (26) of the total station (10) by the control device (13); determining a mapping between the first, the second and the third plane equations in the reference system (24) of the CAD model (25) and the first, the second and the third function equations in the reference system (26) of the total station (10) by the control device (13); and storing the mapping as a transformation function between the reference system (26) of the total station (10) and the reference system (24) of the CAD model (25).

6. The method as claimed in claim 5, wherein a position and/or an orientation of the total station (10) are determined in the reference system (24) of the CAD model (25).

7. The method as claimed in claim 5, wherein measured coordinates, which are measured with the total station in the reference system (26) of the total station (10), are transformed into the reference system (24) of the CAD model (25).

8. The method as claimed in claim 5, wherein intended coordinates, which are determined in the reference system (24) of the CAD model (25), are transformed into the reference system (26) of the total station (10).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 shows a total station, which is deployed in a measurement environment and linked to a control device;

[0024] FIGS. 2A, 2B show the total station (FIG. 2A) and the control device with a CAD model (FIG. 2B) in detail;

[0025] FIGS. 3A, 3B show the CAD model of the objects (FIG. 3A) and the measurement environment 11 with the total station 10; and

[0026] FIG. 4 shows the measurement environment with N measured points.

DETAILED DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 shows a total station 10, which is deployed in a measurement environment 11 and which is connected to a control device 13 via a communications link 12. The measurement environment 11 is embodied as an interior in the exemplary embodiment, the interior being bounded by a floor surface 14, a back wall 15 and a side wall 16; the further boundary surfaces of the measurement environment 11 are not illustrated.

[0028] The measurement environment 11 comprises a plurality of objects. The objects in the measurement environment 11 include the floor surface 14, the back wall 15 and the side wall 16, as well as a window cutout 17 and a door cutout 18. The objects 14, 15, 16, 17, 18 in the measurement environment are imaged in a CAD model.

[0029] FIGS. 2A, 2B show the total station 10 (FIG. 2A) and the control device 13 (FIG. 2B) of FIG. 1 in detail. The total station 10 and the control device 13 are connected to one another by way of the communications link 12.

[0030] The total station 10 comprises a first angle measuring unit 21, which measures a horizontal angle, a second measuring angle unit 22, which measures a vertical angle, and a distance measuring unit 23, which measures a distance. In order to be able to use the total station 10 for layout purposes, the total station 10 must be registered in the reference system 24 of the CAD model 25; i.e., the transformation function between the reference system 26 of the total station 10 and the reference system 24 of the CAD model 25 must be determined.

[0031] Carrying out the method according to the invention for registering the total station 10 in the reference system 24 of the CAD model 25 is controlled by the control device 13. The CAD model 25 of the objects is loaded into the control device 13 and displayed on a display 27 of the control device 13. FIGS. 3A, 3B show the CAD model 25 of the objects (FIG. 3A) and the measurement environment 11 with the total station 10 (FIG. 3B).

[0032] The operator selects three surfaces in the CAD model 25 and marks the surfaces. In the exemplary embodiment, the surface of the back wall of 15 forms a first surface F.sub.1, the surface of the floor surface 14 forms a second surface F.sub.2 and the surface of the side wall 16 forms a third surface F.sub.3. It is essential to the method according to the invention that the three surfaces F.sub.1, F.sub.2, F.sub.3 are disposed in non-parallel fashion with respect to one another. Mathematically, this condition is taken into account by virtue of the normal vectors of the three surfaces F.sub.1, F.sub.2, F.sub.3 spanning a three-dimensional space. The first surface F.sub.1 is characterized by a first normal vector {right arrow over (N)}.sub.1, which is perpendicular to the first surface F.sub.1, the second surface F.sub.2 is characterized by a second normal vector {right arrow over (N)}.sub.2, which is perpendicular to the second surface F.sub.2, and the third surface F.sub.3 is characterized by a third normal vector {right arrow over (N)}.sub.3, which is perpendicular to the third surface F.sub.3.

[0033] The control device 13 determines a first plane E.sub.1, which comprises the first surface F.sub.1, a second plane E.sub.2, which comprises the second surface F.sub.2, and a third plane E.sub.3, which comprises the third surface F.sub.3. The position and orientation of a plane in three-dimensional space is uniquely determined by a point and the specification of the normal vector. Alternatively, the position and orientation of a plane can be set by three points, for example. The control device 13 generates a first plane equation for the first plane E.sub.1, a second plane equation for the second plane E.sub.2 and a third plane equation for the third plane E.sub.3.

[0034] In order to register the total station 10 in the reference system of the CAD model with the aid of the method according to the invention, the total station 10 in the measurement environment 11 is aligned on the point of intersection S of the first, second and third plane E.sub.1, E.sub.2, E.sub.3 in the CAD model (FIG. 3B). This alignment of the total station 10 is defined as start pose by the control device 13. The start pose comprises a start position and start orientation. The total station 10 rotates about the start orientation of the start pose as an axis of rotation 28 and carries out N, N ∈ , different measurements during the rotation. During each measurement, a horizontal angle is measured by the first angle measuring unit 21, a vertical angle is measured by the second angle measuring unit 22 and a distance is measured by the distance measuring unit 23. In the exemplary embodiment, a total of N=19 different measurements are carried out during the rotation of the total station 10.

[0035] FIG. 4 shows the N=19 different measurements. For each measurement, a measured point M.sub.i, i ∈ , with associated measured coordinates is defined, wherein the measured coordinates each comprise a horizontal angle, a vertical angle and a distance. In the next step, the measured points M.sub.i are assigned to the first plane E.sub.1, the second plane E.sub.2 or the third plane E.sub.3 by the control device 13. The measured points M.sub.1 to M.sub.4 are assigned to the first plane E.sub.1 and defined as first measured points A.sub.1, the measured points M.sub.6 to M.sub.14 are assigned to the second plane E.sub.2 and defined as second measured points A.sub.2 and the measured points M.sub.15 to M.sub.19 are assigned to the third plane E.sub.3 and defined as third measured points A.sub.3. The measured point M.sub.5 lies on the line of intersection between the first plane E.sub.1 and the second plane E.sub.2 and cannot be uniquely assigned to either the first plane E.sub.1 or the second plane E.sub.2.

[0036] Following the assignment of the measured points M.sub.i to the first, second or third plane, the control device 13 determines a first function equation for a first plane in the reference system 26 of the total station 10 from the first measured points A.sub.1, a second function equation for a second plane in the reference system 26 of the total station 10 from the second measured points A.sub.2 and a third function equation for a third plane in the reference system 26 of the total station 10 from the third measurement points A.sub.3. The accuracy with which the control device 13 can determine the function equations (first, second and third function equation) in the reference system 26 of the total station 10 depends on the number of respective measured points M.sub.i and the accuracy with which the measured points M.sub.i were determined.

[0037] First, second and third plane equations in the reference system 24 of the CAD model 25 and first, second and third function equations in the reference system 26 of the total station 10 are stored for the first, second and third plane in the control device 13. The control device 13 determines a mapping between the reference system 26 of the total station 10 and the reference system 24 of the CAD model 25 from the plane equations in the reference system 24 of the CAD model 25 and the function equations in the reference system 26 of the total station 10 with the aid of known mathematical or numerical methods, and stores this mapping as a transformation function.

[0038] The transformation function between the reference system 26 of the total station 10 and the reference system 24 of the CAD model 25 can be used for various coordinate transformations between the reference systems 24, 26. By way of example, measured coordinates, which were measured with the total station 10 in the reference system 26 of the total station 10, can be transformed into the reference system 24 of the CAD model 25, or intended coordinates, which were determined in the reference system 24 of the CAD model 25, can be transformed into the reference system 26 of the total station 10.