Places is an experiment to establish geographic locations as NFTs on the Ethereum blockchain. The project aims to curate an ever-growing collection of specific places, submitted and verified by our community, for the purpose of providing free (cc0) queryable place data stored fully on-chain.
Visit the Places website for the latest updates and details.
Contributions are welcome and we invite you to look at the contracts and website, all are open source and available under the MIT License.
| Contract | Etherscan |
|---|---|
| Places | 0xC9CA129DC3a299aF68A215d85771630aec4C3C2b |
| PlacesDescriptor | 0x7C4fAd970E51fBE5CFCa2097C3AA559e3E0aEAf8 |
| PlacesProvider | 0x5219C11e18934AADB4DDa41E3485bD79DAE08F10 |
The core Places.sol contract is immutable and can not be modified. It communicates with the PlacesDescriptor and PlacesProvider contracts. The PlacesDescriptor generates the svg on chain for the ERC-721 tokenURI – no images, tiles, or third party sources in the loop. The PlacesProvider contract maintains a network of "drop" contracts that share on chain information about places and communicate that back.
What's unique about the Places project is that all information is stored on chain. This means all place data is in SSTORE and provided on-demand. Here is a breakdown of that data and what it means.
struct Location {
int256 latitudeInt;
int256 longitudeInt;
int256 altitudeInt;
bool hasAltitude;
string latitude;
string longitude;
string altitude;
}
struct Place {
string name;
string streetAddress;
string sublocality;
string locality;
string subadministrativeArea;
string administrativeArea;
string country;
string postalCode;
string countryCode;
Location location;
string[3] attributes;
}
Represents place information for a geographic location.
- name – string representing the place name
- streetAddress – string indicating a precise address
- sublocality – string representing the subdivision and first-order civil entity below locality (neighborhood or common name)
- locality – string representing the incorporated city or town political entity
- subadministrativeArea – string representing the subdivision of the second-order civil entity (county name)
- administrativeArea – string representing the second-order civil entity below country (state or region name)
- country – string representing the national political entity
- postalCode – string representing the code used to address postal mail within the country
- countryCode – string representing the ISO 3166-1 country code, https://en.wikipedia.org/wiki/ISO_3166-1
- location – geographic location of the place, see Location type
- attributes – string array of attributes describing the place
Represents a geographic coordinate with altitude.
Places provide location information in two formats, string and integers. Since double floating points are not a native type in Solidity, we encode location data up to 14 decimal places and provide a means to decode without losing precision but while also allowing the ability to perform computation on-chain. To bound coordinates positive (North and East) or negative (South and West) use the MAX_LATITUDE_INT, MIN_LATITUDE_INT, MAX_LONGITUDE_INT, and MIN_LONGITUDE_INT integer constants.
Latitude and longitude values are in degrees under the WGS 84 reference frame. Altitude values are in meters.
- hasAltitude – a boolean that indicates the validity of the altitude values, when false no altitude is available.
Decoding a location can be done using GEO_RESOLUTION_INT as a divisor.
3781925338694573 / 100000000000000 = 37.81925338694573
-12247852582409405 / 100000000000000 = -122.47852582409405- latitudeInt – integer representing the latitude in degrees encoded with GEO_RESOLUTION_INT
- longitudeInt – integer representing the longitude in degrees encoded with GEO_RESOLUTION_INT
- altitudeInt – integer representing the altitude in meters encoded with GEO_RESOLUTION_INT
WYSIWYG. We added strings for more future proofing, allowing casting and printing of data.
- latitude – string representing the latitude coordinate in degrees under the WGS 84 reference frame
- longitude – string representing the longitude coordinate in degrees under the WGS 84 reference frame
- altitude – string representing the altitude measurement in meters