Patent ID: 12209862

DETAILED DESCRIPTION

FIG.1shows a schematic depiction of an embodiment of the survey instrument40comprising the targeting unit10, the set of positioning sensors, the imaging sensor unit20and the computing unit30.

The main frame of the survey instrument40comprises a first column41and a second column42. The targeting unit10is attached to both columns41,42so that it is tiltable around a tilting axis61. The tilting of the targeting unit10is preferably realized by a motorized axis62. Manual tilting around the tilting axis61may also be possible under certain circumstances. The survey instrument40comprises a first angle sensor63configured to measure a tilting angle64.

In the depicted embodiment of the survey instrument40is configured to be mounted on a base50and being rotatable about a rotational axis51. The rotation axis51might be a vertical axis during the calibration and measurement operations. The survey instrument40may be rotated manually under certain circumstances, or preferably by a motorized axis52. The survey instrument40comprises a second angle sensor53configured to measure a rotation angle54of targeting unit relative to the base50. The tilting64and rotational angle54retrieved by the first63and second angle sensors53are transferred to the computing unit30. The computing unit30provide driving commands for the motorized axes52,62in order to target a selected feature with the targeting unit10.

In the depicted embodiment of the survey instrument40comprises the imaging sensor unit20as a camera array arranged to different locations in the frame. Other embodiments of the imaging sensor unit20, in particular an imaging sensor unit arranged into a single device, may also be possible. The imaging sensor unit20is configured for a VPS functionality. The VPS might be based on SLAM, SfM or any other alternative methods.

In the depicted embodiment of the portable integrated survey instrument40comprises a wireless interface71as the communication interface. The wireless interface71or a wired interface with equivalent functionality is configured to receive the design data of the environment. The design data comprises absolute position of reference markers. The computing unit30is configured reference the pose of the survey instrument to the received data. The wireless interface71or a wired interface with equivalent functionality might provide measurement and/or design data directly or indirectly, in particular utilizing a cloud server, to further survey instruments40or computing units30.

The survey instrument40comprises an IU21. The survey instrument40might comprise further positioning sensors, in particular positioning sensors based on GNSS, or the wireless unit71. In the depicted embodiment the IMU21is integrated to the base50. Needless to say, that the person skilled in the art can introduce other placement of the positioning sensor. In particular, the IMU21might be integrated to the survey instrument40, the sensors comprised by the IMU21might be distributed such that one or more sensors are integrated to the survey instrument40and one or more sensors are integrated to the base50. Alternatively, at least a part of the sensors from the IMU might be arrangeable to survey instrument40or to the base50in a temporary fashion.

FIG.2shows the environment2containing visual features1,331,332,333,334,335. The environment2in the depicted example is an indoor environment. The present disclosure is no way limited to indoor environments and can be equally applied to outdoor, or mixed in- and outdoor environments. The appropriate visual features might be chosen according to the specific environment2. The survey instrument40may automatically recognize the survey task and the environment2. The survey instrument40may receive operator input on the survey task and the environment2. The environment2comprises a plurality of reference markers1with georeferenced absolute positions. The pose100of the survey instrument40is to be referenced.

FIGS.3aand3bshows a prior art method of referencing the pose100of the survey instrument40by manually targeting the visible reference markers1with referenced absolute positions. Said referencing requires at least two, preferably more reference markers1to be targeted and measured by the measuring beam11of the survey instrument40. The referenced or fine pose101is then determined by an appropriate method e.g. Helmert-transformation, triangulation/resection. Alternative stationing methods are also known in the prior art. Said method requires manual intervention by the operator, which makes it cumbersome and error prone, i.e. in an environment2with a plurality of reference markers1, the unambiguous identification might be complicated.

FIG.4depicts a generic prior art search method, the search method might be based on visual identification or active search. The search method might be based on an active method utilizing a search beam. The survey instrument40recognizes the coarse position of the identified reference markers1in the search field of view12. Since the search field of view12is limited the instrument has to be rotated at least around the rotation axis51to achieve the required total field of view. A tilting around tilting axis61might also be required. The reference markers1found are then targeted and measured. Based on the pose100of the survey instrument40and a database comprising the absolute position of the reference markers1a fine pose101of the survey instrument40might be derived.

While the method depicted inFIG.4does not require direct operator action, due to need of a complete scan it is still time intensive. Furthermore the pose100of the survey instrument40have to be known beforehand at least with the accuracy allowing the unambiguous identification of the reference markers1.

FIG.5ashow the relocation of the survey system40from the fine pose101to a new pose103. For transparency reasons the new pose103is depicted as a new survey location with a set up instrument. The new pose103might also be an intermediate pose along a relocation trajectory. The new pose103is reached along the translation vector110from the fine pose101. The orientation of the instrument40might also change during the relocation. For transparency reasons only translational movements are depicted. The specific aspects of a relocation with orientation change might be applied accordingly.

FIG.5bdepicts the relocation of the instrument as viewed by the instrument40, in particular the imaging sensor unit20. The imaging sensor unit20record a series of prominent visual features. Prominent visual features during an indoor survey might be reference markers1, corners, power sockets, switches, corners of doors/windows332, railings, construction material335, etc. For outdoor or mixed in- and outdoor survey tasks a different set of prominent visual features might be more appropriate.

During the relocation of the instrument40along a translation vector110, the position of the visual features1,332,335as viewed by the imaging sensor unit change with a translation vector111. The two translation vectors110,111are of equal length and opposite direction. The coarse pose of the survey instrument40can be derived from the translation vector111observed by the camera. The derivation of the rotation movement is analogous.

Especially for the here depicted indoor survey, the imaging sensor unit20might experience difficulties for tracking the visual features1,332,335. Reasons for that might be masking of the visual features by other object, stark contrast changes in the environment2or on the visual features1,332,335themselves. For that purpose the survey instrument is equipped with an IMU21. The IMU21can provide the movement information if the tracking of the visual features1,332,335is lost as well as provide information to re-establish the tracking of the visual features1,332,335.

FIG.6ashows a situation where the pose100of the survey instrument is not known with geodetic accuracy. The coarse pose102derived from the IMU and VPS data. Based on the coarse pose102and digital model of the environment comprising the position of a plurality of reference markers1the survey instrument can locate a reference marker1utilizing a limited search, in particular no search beyond the sighting and aiming step. The extent of the limited search might be derived from the estimated variance of the coarse pose. The limited search might be selected so that an ambiguity in the identification of the reference marker1has the lowest probability.

Upon unambiguously identifying the reference marker1in the search field of view12, the reference marker1is automatically targeted and measured by the measuring beam11as shown inFIG.6b. The fine pose101is determined by automatically targeting and measuring at least a second reference marker1as shown inFIGS.6cand6d.

FIG.7shows an embodiment wherein the computing unit30displays the design data200of the environment2. The design data comprises the position of the reference markers1in the environment2. The computing unit30might also display the pose100of the instrument40. The pose100of the instrument40might be a fine pose or a coarse pose. The displayed symbol might be different for fine and coarse poses.

The operator might select a requested second location for the continuation of the survey task. The computing unit30calculate a calculated visibility and/or unambiguity the reference markers1in the proximity of the requested second location. The computing unit30calculate a proposed second location201based on visibility and/or unambiguity the reference markers1. The computing unit30might consider other parameters in calculating the proposed second location201, in particular an accessibility of the proposed second location201. Needless to say that the person skilled in the art could provide and combine further similar parameters in providing a method for selecting the proposed second location201.

The computing unit30might provide guidance instruction202for the operator to reach the proposed second location201. The guidance instructions202might comprise a path plotted in the design data200, arrows showing the walking direction, or similar visual or alternative, in particular audio, instructions. The computing unit30might comprise a handheld unit to display the guidance instructions202.

Although aspects are illustrated above, partly with reference to some specific embodiments, it must be understood that numerous modifications and combinations of different features of the embodiments can be made. All of these modifications lie within the scope of the appended claims.