**1. Introduction**

Since the early 2000s, Unmanned Aerial Systems (UAS) have become increasingly significant for both scientific as well as commercial applications [1,2]. The advent of this low cost, reliable, and user-friendly platform, as well as recent developments in digital photogrammetry and structure from motion (SfM) image processing software solutions, create new opportunities for collecting timely, tailored, detailed, and high-quality geospatial information. Studies on the various surveying technologies provide evidence that UAS can fill the data acquisition gap between time-consuming but highly accurate ground surveys, and faster yet relatively expensive classical aerial surveys [3]. Evidence of numerous UAS-based data acquisition missions across the globe prove the capabilities of

this innovative technique. The platform has been applied to various domains such as agriculture [4,5], geosciences [6–10], and disaster risk management [11,12]. [13] provides a detailed review of remote sensing applications based on UAS. General advantages of UAS as remote sensing platform are the flexibility regarding application and usage, the high resolution of images, the ease-of-use and the immediateness of the results. Common drawbacks are regulatory uncertainties [14] and time-consuming ground control measurements if real-time kinematic (RTK) or post-processing kinematic (PPK) based workflows are not an option. Resulting data products include true orthoimages, digital elevation models and 3D point clouds, which are increasingly harnessed as a spatial framework to accomplish land administration processes. The applicability of UAS for various cadastral purposes has been tested in various pilots, e.g., meeting juridical boundary requirements in western Europe [15–17], mapping customary land rights in Namibia [18], and boundary mapping in Indonesia [19]. All pilot studies remained at a small-scale, reaching from several households to entire neighbourhoods.

Compared to other remote sensing techniques such as satellite images or classical aerial images, UAS data has clear advantages in the resolution, which is often below 10 cm and provides a high level of detail. To reach low ground sampling distances, flight height is usually set to less than 100 m–a limitation which is mostly also given by the national UAS regulations. Thus, the scale of one UAS missions is very low, reaching from a few hectares up to hundreds of hectares, depending on the platform, the field of view of the sensor, image overlap and flight pattern. Thus, aerial/satellite images are more suitable for large-scale mapping. With a particular focus on land rights recording, [20] concluded additional advantages of UAS data collection workflows: reliability of the data, open and transparent data collection procedure and the ease of implementation. The latter parameters are of particular importance to the implementation of fit-for-purpose land administration tool with a strong focus on developing countries.

While UAS appear to be a promising technology, there has been little discussion in the literature as to what extent this technology can match the needs of communities and governments especially when land administration is absent, incomplete, or in a state of decay. A flexible and pragmatic approach to meet the needs of people and their relationship to land refers to the key principle of recent land administration approaches [21–23]. Unlike leveraging technical standards, these approaches advocate that the data acquisition method of the underlying spatial framework should have a strong focus on managing current land issues in a specific context. Little has been done to study how different innovative geospatial technologies fit different needs.

Therefore, this paper aims to critically examine the match between stakeholders' needs and the characteristics of the UAS data acquisition workflow and its final products as valuable spatial information for land administration. This was achieved through undertaking a case study in Rwanda where a mixed methods approach was applied. First, the needs of potential end-users were investigated; second, the UAS technology was trialled in Rwanda and third, the performance of the entire UAS-based data acquisition workflow and its ability to match end-user requirements was assessed. A combined analysis of qualitative, as well as quantitative results, provides the empirical basis for discussing the degree of fitness of UAS technology for matching users' needs. The integration of the results in a socio-technical discussion [24] makes this paper a significant contribution as it reveals the opportunities and limitations of UAS technology in the context of current discourses in land administration.

The remainder of this article is organized as follows. After a short overview of the study area in Rwanda, the third section describes the research methodology. The fourth section presents the results focusing on the needs assessment, the UAS test flight missions, and a synthesis, which ultimately debates the fitness of use of UAS technology to attain land administration and spatial planning processes. The discussion relates the results of this study to existing scientific investigations and further reflects on the significance of the work. The conclusion with opportunities and remaining challenges as well as a future outlook complete the article.

#### **2. Study Area**

Rwanda, with an area of over 26,000 km<sup>2</sup> and a population of almost 12 million people, is the most densely populated country in Africa (467 per km2) [25]. The population of Rwanda is still mostly rural, with 83% living in rural areas [25] with the majority depending on subsistence farming although less than half the population own less than 0,5 ha of land or none at all [26]. Despite its land scarcity and prevalence of hilly landscapes, the country continues to be highly reliant on agriculture as a form of employment and subsistence, and an increasing population exerts a growing demand for housing and infrastructure. After independence in 1962, land ownership in the country has evolved from customary law to a system of state ownership. This shift was formalized with the implementation of a new land policy in 2004 and the Organic Land Law (OLL) in 2005, which aimed to improve tenure security through land registration, facilitate the development of an equitable land market in Rwanda and promote the sustainable use of land. In approximately 2013, a country-wide land tenure regularization program (LTRP) was completed where more than 11 million parcels were demarcated and almost 9 million parcels titled to offer Rwandan citizens a range of perceived social, legal and economic benefits. The LTRP used 96% aerial images captured in 2008 and 2009 and 4% satellite imagery as base data to demarcate and adjudicate parcel boundaries in a community-mapping exercise [27]. Geo-information derived from the LTRP has also enabled the development of a national cadastral map (title-based land administration system), which now underpins a range of purposes [28]. However, base data has not been updated since and geo-information is still based on orthoimages from 2008/2009.

When it comes to the organized use of UAS, Rwanda can be considered as progressive in comparison to other East African countries. At the 2017 World Economic Forum in Davos, high-level delegates from the Government of Rwanda promoted Rwanda as the first country to adopt performance-based UAS regulations. They further outline that development of infrastructure and policy frameworks will spur business growth and social impact. In October of 2016, Zipline and the Government of Rwanda launched the world's first national drone delivery service to make on-demand emergency blood deliveries to transfusion clinics across the country. After initial difficulties to receive the permission to operate beyond visual line of sight, the business experienced constant growth. In addition to introducing new products, Zipline plans to build a second distribution centre in the country's east [29]. Besides foreign businesses, local UAS companies such as Charis UAS Ltd. provide professional services in various UAS industries including mapping, crop monitoring, surveying and aerial photography.
