Journal of Surveying Engineering

Data fusion is an important issue as multi-source observation technology is widely used in geoscience. Although the problem of robust estimation exists widely in the data fusion, few solutions have been reported. This paper investigates a solution for the robust estimation of heterogeneous data fusion implementing classification, robust estimation, and data fusion. A new approach based on ${\mathrm{M}}_{\mathrm{split}}$ estimation is constructed to define accurate scales for multi-source observation data and, adopting the Institute of Geodesy and Geophysics (IGG)III weight function, an iterative algorithm is proposed for the above problem. Finally, two instances are considered in verifying the feasibility of the presented solution.

Abstract

A complete treatment of the intersections of two geodesics on the surface of an ellipsoid of revolution is given. With a suitable metric for the distances between intersections, bounds are placed on their spacing. This leads to fast and reliable algorithms for finding the closest intersection, determining whether and where two geodesic segments intersect, finding the next closest intersection to a given intersection, and listing all nearby intersections. The cases where the two geodesics overlap are also treated.

Practical Applications

The intersection of lines plays a central role when performing geometric operations on geographical objects. Often, this is performed on a map projection; but this has the disadvantage that the projection introduces an inevitable distortion. It is, therefore, preferable to compute the intersections directly on the surface of the Earth (or, more precisely, on some ellipsoidal approximation to the Earth); in this case, the lines in question are best taken to be geodesics, the generalization of straight lines to a curved surface. This paper describes a fast, reliable, and accurate method of computing the intersections of geodesics.

Abstract

The demand and establishment of continuously operating reference stations (CORSs) are growing fast around the world including in African countries due to having several benefits, such as the provision of accurate, homogeneous positional coordinates and the reduction of duplication and unnecessary transformation. Ethiopia prepared a 10-year geodetic infrastructure development implementation plan for modernizing geodetic services via the CORS network. To fully utilize the proposed CORS network, there is a need to investigate the overall status and limitations of the geospatial experts. The objective of this study was to gauge the awareness level and readiness of the experts to use the existing and proposed CORS in Ethiopia. A mixed research method was applied. About 244 respondents from 68 geospatial industries throughout the country filled out the survey questionnaires, and descriptive statistics were used to analyze the data. The findings of the study revealed that only 16.4% of the respondents had a better understanding of the concept of CORS and were able to operate CORS data, while 83.6% of respondents lacked the knowledge required to effectively use CORS technology for their geospatial applications. Extensive training must be given for both academics and nonacademics geospatial professionals because 98.4% of the participants currently express a desire for basic short-term CORS training that teaches them the best use of CORS technology.

Practical Applications

The study attempted to investigate the overall status and limitations of the geospatial professions in Ethiopia concerning CORS technology. This study is crucial for the different global navigation satellite system (GNSS)/CORS or geospatial stakeholders such as the International GNSS Service (IGS), Space and Earth Geodetic Analysis Laboratory (SEGAL), the United Nations Committee of Experts on Global Geospatial Information Management (UN-GGIM), and the UN-GGIM Subcommittee on Geodesy, Africa Geodetic Reference Frame (AFREF) project to evaluate the progress of implementation of a global geodetic reference frame (GGRF) over the globe and a unified geodetic reference frame in Africa. The findings of the study revealed that a significant portion of the geospatial professions never used CORS due to a lack of understanding of CORS, being unable to operate it, and their organization’s lack of GNSS equipment. Establishing GNSS/CORS infrastructure by itself is nothing unless work has been done on providing technical skills in data handling and dissemination and precise analysis using scientific GNSS processing software in conjunction with the technology expansion. As a result, the aforementioned and other concerned nongovernmental organizations (NGOs) should work on the capacity development of the academics and nonacademics geospatial professionals whose countries show a knowledge limitation in such technology.