Map tiles are 256 x 256 pixel panels treated as display units.
EPSG:3857WGS84 / Pseudo Mercator (Web Mercator).
Zoom level is the level at which the base tile (256 x 256 pixels; 2^8 x 2^8) is recursively refined. The zoom level of the base tile is 0. Maximum zoom level of vector map is 21.
pixelCoordinate = worldCoordinate * 2^zoomLevel
Road network directions data can be acquired and confirmed by reading street signs from Street View imagery. Roadway details like the size of the road could be recognized by (Satellite/Aerial) overhead imagery.
Google Traffic provides real-time traffic conditions on major roads and highways in over 50 countries, using technology from ZipDash. Live traffic data are crowd-sourced from Android phones which act as an army of car-mounted traffic monitors. The iPhone Maps application, however, does not support traffic crowdsourcing. Just as with the highways, the colors (of arterial roads) correspond to the speed of traffic (relative to the speed limit of the road): green is free sailing, yellow is medium congestion, red is heavy congestion, and dark red is stop-and-go traffic.
(18:39) Speed limit data turns out to be really difficult to get canonical sources for. And the only way, I think, it can be done is by driving all the roads and picking up images.
(19:20) And so actually creating a model of how fast vehicles actually travel and whether or not they're over the speed limit or under the speed limit is actually very, very difficult, because it turns out that the data is just very, very noisy.
According to Richard Russell on Quora, Google Maps' estimated time of arrival (ETA) are based on a variety of things, depending on the data available in a particular area. These things range from official speed limits and recommended speeds, likely speeds by road types, historical average speed data over certain time periods (sometimes just averages, sometimes at particular times of day), actual travel times from previous users, and real-time traffic information.
Google Transit is a public transportation planning tool which integrates transit stop, route, schedule, and fare information. Google Transit resources: Google Developers; General Transit Feed Specification (GTFS); list of public GTFS feeds; transit agencies on GTFS Data Exchange.
Early versions of Google Maps provided information to users about how long it would take to travel a particular road in heavy traffic conditions.
Google Maps Content Partners/Providers are organizations that contribute authoritative map data to Google. Selected providers are identified in a credits line at the base of the user interface. Under the terms of Google's content license agreement with content partners, Google agrees not to provide partners' content to third parties in a raw, unmodified form.
List of Content Partners:
Google Maps' Project Ground Truth keeps Google Maps as up to date and accurate as possible for over 50 countries by:
Google I/O 2013 - Project Ground Truth: Accurate Maps Via Algorithms and Elbow Grease showed some under-the-hood details of the project. The Ground Truth project hired many operators for each country maintained, which is quite expensive in all aspects. Computer vision algorithm are used to extract addresses, one-way streets, bicycle lanes, types of roadways, and business logos from Street View, internally implemented as Atlas.
Selected Google Maps API:
Google Maps Engine API: store geographic data, visualize as overlay. [To be deprecated on Jan 29, 2016; An alternative may be Google My Maps]
Google Earth Engine: satellite imagery of the Earth over 40 years. Applications include deforestation, land cover change, urban sprawl, etc.)
Projects that used Google Earth Engine: earthquake & flood risk modeling; drought monitoring, agricultural water consumption estimation, epidemic disease risk modeling; Google I/O 2014: Saving trees and saving lives with petapixel-scale computing
DirectionsResult with route and duration in response.
DirectionsRequest:durationInTraffic specifies whether the
DirectionsLeg result should include a duration that takes into account current traffic conditions.
This feature is only available for Google Maps API for Work customers.
The time in current traffic will only be returned if traffic information is available in the requested area.
Typical traffic: Google Maps only provide typical traffic layer in half-hour intervals, no directions.
Historic traffic: Google Maps API for Work claimed to provide historic traffic data, which doesn't seem to be currently supported.