ABSTRACT
This chapter demonstrates the construction of a special type of web maps—web maps for crowdsourcing of spatial data. Crowdsourcing web maps are used to collect, permanently store, and display spatial information contributed by numerous users. The most well-known example of crowdsourcing is Wikipedia2, an encyclopedia created and edited by volunteers throughout the world, operating since 2001. From the technical point of view, crowdsourcing requires at minimum an interface where the contributors can log in and give their input, and a database where the inputs of the various contributors are being permanently stored. The chapter illustrates the steps for building a simple crowdsourcing web application. The steps include adding a drawing control for drawing shapes on a Leaflet map, translating drawn shapes to GeoJSON, adding a form where the user can enter attribute values along with the drawn shapes, and adding a mechanism for sending the drawn shapes to a CARTO database for persistent storage.
