M.N. Koeva

Using UAVs for map creation and updating. A case study in Rwanda

Aerial or satellite images are conventionally used for geospatial data collection. However, unmanned aerial vehicles (UAVs) are emerging as a suitable technology for providing very high spatial and temporal resolution data at a low cost. This paper aims to show the potential of using UAVs for map creation and updating. The whole workflow is introduced in the paper, using a case study in Rwanda, where 954 images were collected with a DJI Phantom 2 Vision Plus quadcopter. An orthophoto covering 0.095 km2 with a spatial resolution of 3.3 cm was produced and used to extract features with a sub-decimetre accuracy. Quantitative and qualitative control of the UAV data products were performed, indicating that the obtained accuracies comply to international standards. Moreover, possible problems and further perspectives were also discussed. The results demonstrate that UAVs provide promising opportunities to create high-resolution and highly accurate orthophotos, thus facilitating map creation and updating.

A procedure for semi-automated cadastral boundary feature extraction from high-resolution satellite imagery

Abstract Fit-for-purpose land administration aims to align cadastral policies, administration and technology selection with the prevailing societal needs and capacity within a country context. It seeks to support delivery of more rapid and low-cost cadastral boundary mapping – and ultimately more widespread land tenure security. The philosophy suggests that when high positional accuracies are not the primary concern, but when time pressure is, high-resolution satellite images can serve as a source for creating cadastral boundary information. This paper explores the potential of mean-shift segmentation plug-in in QGIS to semi-automatically extract cadastral boundaries in rural areas – based on the land cover information from WorldView-2 satellite images. The segmentation gives a vector file satisfying many cadastral boundary requirements and ready to be used in a GIS environment. The buffer overlay method was used to assess the quality of extracted boundaries. For a non-vegetated terrain having visible boundaries, the approach could be taken as an alternative to support existing, relatively slow, boundary mapping approaches by minimizing the effects of manual digitization and surveying.

Integrating Spherical Panoramas and Maps for Visualization of Cultural Heritage Objects Using Virtual Reality Technology

Development and virtual representation of 3D models of Cultural Heritage (CH) objects has triggered great interest over the past decade. The main reason for this is the rapid development in the fields of photogrammetry and remote sensing, laser scanning, and computer vision. The advantages of using 3D models for restoration, preservation, and documentation of valuable historical and architectural objects have been numerously demonstrated by scientists in the field. Moreover, 3D model visualization in virtual reality has been recognized as an efficient, fast, and easy way of representing a variety of objects worldwide for present-day users, who have stringent requirements and high expectations. However, the main focus of recent research is the visual, geometric, and textural characteristics of a single concrete object, while integration of large numbers of models with additional information—such as historical overview, detailed description, and location—are missing. Such integrated information can be beneficial, not only for tourism but also for accurate documentation. For that reason, we demonstrate in this paper an integration of high-resolution spherical panoramas, a variety of maps, GNSS, sound, video, and text information for representation of numerous cultural heritage objects. These are then displayed in a web-based portal with an intuitive interface. The users have the opportunity to choose freely from the provided information, and decide for themselves what is interesting to visit. Based on the created web application, we provide suggestions and guidelines for similar studies. We selected objects, which are located in Bulgaria—a country with thousands of years of history and cultural heritage dating back to ancient civilizations. The methods used in this research are applicable for any type of spherical or cylindrical images and can be easily followed and applied in various domains. After a visual and metric assessment of the panoramas and the evaluation of the web-portal, we conclude that this novel approach is a very effective, fast, informative, and accurate way to present, disseminate, and document cultural heritage objects.

Object-based image analysis for cadastral mapping using satellite images

Cadasters together with land registry form a core ingredient of any land administration system. Cadastral maps comprise of the extent, ownership and value of land which are essential for recording and updating land records. Traditional methods for cadastral surveying and mapping often prove to be labor, cost and time intensive: alternative approaches are thus being researched for creating such maps. With the advent of very high resolution (VHR) imagery, satellite remote sensing offers a tremendous opportunity for (semi)-automation of cadastral boundaries detection. In this paper, we explore the potential of object-based image analysis (OBIA) approach for this purpose by applying two segmentation methods, i.e. MRS (multi-resolution segmentation) and ESP (estimation of scale parameter) to identify visible cadastral boundaries. Results show that a balance between high percentage of completeness and correctness is hard to achieve: a low error of commission often comes with a high error of omission. However, we conclude that the resulting segments/land use polygons can potentially be used as a base for further aggregation into tenure polygons using participatory mapping.

GEOGRAPHIC INFORMATION SYSTEM – TOBEL

TOBEL is Geographic Information System entirely developed by one of the leading Bulgarian Geo-information companies – Mapex JSC. The system is based on modern information technology and it is especially designed for Bulgarian authorities. GIS – TOBEL provides to municipalities extraordinary quantitative and qualitative benefits. The system offers a method of quick access, evaluation, and format conversion. It also allows producing interactive maps from different sources, leveraging database information, and automating work processes. The paper contains a description of the main functions of the system, the used data and the whole process of development and system integration in Bulgarian Municipalities. The examples of successful working GIS systems integrated from our company are demonstrated.