High-Accuracy Location Services, Community Mapping, and the Future of Geospatial Data Collection

Across the developing world, nearly a billion people live without legal title to their land. In order to formalize this property, governments need to issue titles and create secure registries in which to record them. But unlike other types of property, parcels of land cannot be registered until they have been defined. Delineating one person’s property from another’s is a serious technical challenge and a prerequisite for granting secure legal titles.

This challenge is all but insurmountable if approached with conventional methods. Professional surveying is extremely accurate but prohibitively expensive in the developing world. Recent advances in GNSS technology have weakened the correlation between precision and cost, but survey-grade accuracy is not yet widely affordable.

Widespread access to high-accuracy geospatial data is critical for formalization efforts because expense is not the only problem with depending on professional surveyors. Documenting the world’s informal property involves a more fundamental issue of scale; there is not enough time for the small number of professional surveyors to register it all. According to the Cadasta Foundation, there are fewer than two professional surveyors per 10,000 square kilometers of land in the Ivory Coast and Tanzania, compared to 41 per 10,000 square kilometers in the United States. There were only 74 registered land surveyors in Uganda in 2015 and an estimated 15 million parcels of informally owned land. With more than 200,000 parcels per registered surveyor, Cadasta calculates that it would take them over a thousand years to finish the job.¹

With more than 200,000 parcels per registered surveyor, it would take Uganda over a thousand years to finish the job.

When everyone has access to high-accuracy location data, some of the most time-consuming and expensive parts of the formalization process can be completed more quickly and cheaply at a local level. But collecting accurate, high-integrity geospatial data is only one part of the challenge. Formalization also requires the collection of a great deal of information about the people living in these communities, and this information should be collected in a way that respects local cultural sensitivities and land use practices, as well as the privacy of the landholders. This is the other half of community mapping.

One of the primary obstacles to the acceptance of community mapping is that it does not produce data as accurate or trusted as that gathered by professionals. On the surveying side this is largely a technical problem: the hardware and expertise required by traditional geospatial surveying methods is beyond the reach of most communities. But when it comes to gathering non-geospatial information about properties, their attributes, the people who own them, and their rights, there is a problem of trust. Professional surveyors and government officials are considered trustworthy to a degree that members of the community, with their diverse and potentially conflicting interests, may not be. In order for community mapping to have the greatest impact, the information it produces must be trusted enough to be accepted by the authorities who control access to services.

Mapping conducted with cheap and accessible tools is at present unlikely to meet legal standards for property registration, making it of limited use as collateral for a loan. Moreover, lenders may not be willing to accept low-value properties as security for loans, regardless of the formal ownership status.² Expanding access to capital is often cited as the primary economic benefit of formalization, but it is only one positive impact of many. Community mapping can be used to increase tenure security and bootstrap financial inclusion, even when it does not result in formal registration. Indeed, increased tenure security can itself be a driver of increased investment in land. The information gathered can provide strong evidence for the legal defense of property rights, increasing security of tenure. For example, in 2011 community maps created by the Basarwa Bushmen helped them to challenge the Government of Botswana in court and “win back the right to live on their land.”³

Community mapping can be used to increase tenure security and bootstrap financial inclusion.

Many in the international development community argue that rather than trying to adopt more accurate mapping tools and techniques—which have been prohibitively expensive—it would be better to relax surveying accuracy standards. But there are good reasons to resist this argument, especially now that high-accuracy tools are becoming more accessible. First, governments have little incentive to relax their standards, given the risk of increasing the number of legal boundary disputes. More accurate surveying enhances the clarity and security of land claims. Second, quality of surveying and security of title should not be tied to the income of the property owner. Third, in a rapidly urbanizing world, accuracy is increasingly important: errors on the order of meters, even decimeters, can encompass a large percentage of the area of a small apartment. This is one reason that the focus of formalization efforts has to date been largely on rural surveying. Fortunately, cheap tools are emerging that promise to make professional-grade accuracy accessible to everyone. It is important to note that there will still be a role to play for expert surveyors, who will help design community mapping efforts, train the participants, and provide quality control of data gathered.

Position measurements using a single frequency are vulnerable to interference and accurate, at best, to about five meters. This is fine for most people’s daily use, and in developed areas Wi-Fi signals can be used to augment accuracy. Until May 2018, for example, every smartphone ever released used a single-frequency receiver. But errors on the scale of meters are not good enough for survey work, which should be accurate to the one to ten centimeter range, depending on local standards and the type of surveying.

By making use of a second signal frequency, dual-frequency receivers can correct for delays caused by the ionosphere, which are the greatest single contributor to inaccuracy. Using a second frequency also provides greater signal redundancy, allowing for better error-correction and improved satellite availability in tree cover and urban canyons. With error-checking algorithms that can identify faulty satellite signals, dual-frequency receivers produce measurements that are not only far more accurate but also significantly more trustworthy. This last quality is important when it comes to registering land, as it allows the authorities validating title claims to have confidence in the integrity of the data they are given. Dual-frequency receivers also resolve positions more quickly than single-frequency receivers, so the surveyor does not have to wait as long on a reference point acquiring multiple satellites.⁴