FOAM is designed to empower users to build a consensus-driven map of the world that can be trusted for every application. As technology evolves and changes, maps need to change too. FOAM secures physical space on the blockchain, harnessing the power of Ethereum with a cryptographic software utility token used to provide computational work and verification to the network.

The goal of the Proof of Location solution is to provide the framework and infrastructure to support a decentralized, privacy preserving, highly accurate, censorship resistant alternative to GPS. Location is a fundamental infrastructure protocol needed to achieve the full vision of a decentralized ‘web3’ economy and can foster an ecosystem of applications built on top of a verified location standard.

Proof of Location is the primary utility arising from use of the Crypto-Spatial Coordinate and Spatial Index Visualizer elements discussed in our previous blog posts. Proof of Location will inherently be an iterative process which involves the use of token curated registries by users to contribute, verify and determine Proofs of Location.

In general any system for Proof of Location will need to bootstrap itself into existence from the weakest self attestation claims to strong fraud proof authority based claims.

In general any system for Proof of Location will need to bootstrap itself into existence from the weakest self attestation claims to strong fraud proof authority based claims. For FOAM the starting point is Static Proof of Location for Geographic Points of Interest, places and locations for a consensus driven map of the world. Yet a Dynamic Proof of Location system can account for Proof of Location in space and over time by accounting for mobile and dynamic location customers. As described in our previous posts this kind of system will require a robust Byzantine Fault Tolerant time synchronization protocol over radio.

Static Proof of Location

As outlined above, the CSC standard is a registry that enables the blockchain to act as a registry of spatial contracts and, by extension, allow spatial contracts to be queried and displayed on the Spatial Index Visualizer. Token Curated Registries (TCRs) are a crypto-economic model for curating human readable lists with intrinsic economic incentives for independent token holders to curate the list’s contents.

The content of the list is backed by staked tokens and token holders vote on additions to the list with the goal of raising the value of their token by producing a valuable list, as described in more detail below. The theory and thinking behind TCRs is somewhat comparable to private maps and locally curated points of interest — the contributors are incentivized to ensure a high-quality result, for economic or reputational reasons.

In this light, FOAM users can be the contextualized successors to the work of cartographers throughout history that maintained geographic data about everything from topography to dense urban streets.

CSCs and TCRs together make a powerful combination for a new form of mapping and maintaining what are known as Points of Interest (POI). In this light, FOAM users can be the contextualized successors to the work of cartographers throughout history that maintained geographic data about everything from topography to dense urban streets. However, FOAM takes this history a step further by granting control over the registries of POI to locally-based markets and community forces, allowing the information provided to be validated by those who contribute to the relevant locality.

For more information on Static Proof of Location please see our blog post on Token Curated Registries for Points of Interest:

Dynamic Proof of Location

FOAM hopes that the Cartographers and users will contribute the necessary individual work, resources, and effort themselves to contribute to the ongoing community-driven growth and upgrade of this important cartography project. With the addition and use of necessary radio hardware, as described in more detail below, Proof of Location could be expanded to further prove location status through a time synchronization protocol intended to ensure continuity of a distributed clock, whereby specialized hardware can serve as a Zone Anchor and synchronize nodes’ clocks over radio to provide location services in a given area, called a Zone (the nodes providing such services being Verifiers and Anchors (collectively, the operators)).

Just as GPS can determine location through the difference in time and distance of radio signals, time difference of arrival, with a high-precision clock signal, the FOAM network can use the relative geometry between beacons to compute a node’s distance, thereby enabling a secure, spatially distributed location system. In that context, the FOAM token would be used as a safety deposit for Zone operators, which is needed to enable operators to provide the necessary work of time synchronization to the network and serve as collateral that the rules of the protocol will be followed. If the rules of the protocol are not followed by the operators, their license would be revoked and their staked FOAM tokens forfeited along with it. Zone operators are rewarded in new tokens for providing their work, in the form of time synchronization services, to the network.

Verifiers are computers that check Zones for fraud and compute location algorithms from the time data. Together the work provided by the Verifier and Zone allow them to mine triangulations. Their collective output result in data that can be computed for triangulation and in return for this process these actors are eligible for newly issued tokens from the FOAM protocol as a [reward for this output]. In return for a Zone operator providing this service, they may receive a fee from customers who wish to verify their location through the protocol. The denomination of this fee would depend on the preference of the Zone. Proof of Location can therefore provide consensus on whether an event or agent is verifiably at a certain point in time and space producing a digital authentication certificate that is fraud proof, called a Presence Claim.

As discussed above, one use of the FOAM Token within the protocol would be as the safety deposit to participate in the protocol correctly and contribute the necessary work, security and computation that enables time synchronization. The staking of the token is needed on the Ethereum blockchain for the Zone operators to be granted access to the shared state machine of any given Zone, meaning each Zone is its own child blockchain.

Participating in the FOAM Network as a Cartographer — A Summary

At launch, FOAM token holders can become Cartographers and can contribute to their locality and interests by curating, mapping and verifying the locations of static objects. As the FOAM network grows and Cartographers begin to fully explore and map the world, once the necessary technical upgrades are made, FOAM token holders may decide to contribute to the network as one of the entities above. In order to prepare their area for these upgrades, the Cartographers can also stake tokens in the Signaling process, to incentivize dynamic Proof of Location services to be offered in their area.

The FOAM protocol provides the technology, framework and incentives for service operators to set up hardware Zone Anchors, broadcast coverage, and earn block rewards.

The FOAM protocol provides the technology, framework and incentives for service operators to set up hardware Zone Anchors, broadcast coverage, and earn block rewards. In the Proof of Location protocol there are three classes of nodes: Zone Authorities are full nodes, Zone Anchors are partial nodes, and Verifiers ‘mine’ triangulations, computing locations from time stamped data.

The FOAM Token is the native software utility token of the FOAM network. To begin offering location-based services as a Zone Anchor or Zone Authority, or to offer computing power as a Verifier, tokens must be staked and will be held as safety deposit over a limited time. This staking ensures that fraudulent behavior which violates protocol rules can be penalized.