Communication requires having a common language, a lingua franca, between agents. This language could emerge via a consensus process, but it may require many generations of trial and error. Alternatively, the lingua franca can be given by the environment, where agents ground their language in representations of the observed world. We demonstrate a simple way to ground language in learned representations, which facilitates decentralized multi-agent communication and coordination. We find that a standard representation learning algorithm -- autoencoding -- is sufficient for arriving at a grounded common language. When agents broadcast these representations, they learn to understand and respond to each other's utterances and achieve surprisingly strong task performance across a variety of multi-agent communication environments.

Densely and regularly sampled ground-level imagery collected from semi-automated vehicle collection platforms (e.g. Street ViewTMor EarthMineTM) is rapidly becoming available on a global scale. Ground level views of neighborhoods around the world can provide unique regional indicators (e.g. demographics, zoning, socioeconomic health) at a finer resolution than current census data. To this end, this paper introduces the first unsupervised method for automated hierarchical modeling of high-level latent regions using densely sampled, geotagged ground imagery at a global scale. Our unsupervised, nonparametric approach models a multi-scale regularly sampled grid of panoramic ground-level images (where available), producing a multi-scale, multivariate estimate of the latent types of locations (e.g. commercial street, wooded area, park, country road, suburban street, etc.). Region types are model distributions of location types characteristic of particular neighborhoods, towns, or cities. These latent region types are used to cluster all locations into distinct geographic entities with regional signatures that can be used for comparison. We show the effectiveness of this method for discovering regional distributions at vastly different scales, including the Boston area, the United States, and the World.