| Preprint | |
| Report number | CERN-BE-2023-009 |
| Title | LGC: Analysis and pratical example of direct levelling observations referenced on the CERN local Geoid model |
| Author(s) | Kautzmann, Guillaume (CERN) ; Klumb, Francis (CERN) |
| Publication | 2022 |
| Imprint | 31 Oct 2022 |
| Number of pages | 6 |
| Presented at | 16th International Workshop on Accelerator Alignment (IWAA 2022), Ferney-Voltaire, France, 31 Oct - 4 Nov 2022 |
| Subject category | Engineering |
| Keywords | LGC ; accelerator ; alignment ; Geoid model ; levelling ; surveying ; DLEV ; geo-referenced levelling stations |
| Abstract | Direct levelling is performed extensively in the CERN surveying processes for accelerator elements’ alignment and positioning. LGC software (Logiciel Général de Compen- sation1) computes results and associated statistics for ob- servations used by surveyors. Traditionally, direct levelling campaigns are computed separately from the planimetry, using simple differences of height -called in LGC *DVER observation- between two measured points. LGC provides another observation model, called *DLEV, using offsets to a horizontal plane at the position of the station. The level plani- metric position must therefore be known or be computable by additional observations. This more rigorous model al- lows a better integration in 3D computation involving other instruments, such as laser trackers or total stations. This article reviews the traditional method and analyses the use of geo-referenced levelling stations for accelerator element surveying. The influence of the station planimetric position precision and of the geoid model used are studied and illustrated with a practical case. |
| Submitted by | jeanette.kotzian@cern.ch |
Registro creado el 2023-02-15, última modificación el 2023-04-19
