For those wondering exactly what planimetrics are and why they should care, read on. Otherwise, you can skip to the last paragraph and download the data here.
Planimetric mapping is the capture of geographic features from aerial survey (i.e., capture of aerial photography) that are traditionally mapped in two dimensions and are therefore exclusive of elevation. Quite simply these are the visible features that can be digitized from aerial photography. Often referred to as planimetric features or simply planimetics, these geographic features in their sum total essentially represent the base map data (i.e., layers) for a specific area.
NYC DoITT first developed a planimetric database in 2000. The data was captured from the first ‘modern’ aerial survey of the New York City that took place in 1996. Referred to as the NYC Landbase, components of this effort were the establishment of:
- a ‘database design’ (the delivery was ArcInfo coverages);
- coverage parameters (e.g., scale, projection, precision, fuzzy tolerance and dangle length);
- the specific features to be captured;
- and a classification scheme (i.e., feature codes).
The delivery of the data was by 2,500′ x 2,500′ tiles, which directly corresponded to the orthophotography tiles.
A subsequent ad-hoc update to the planimetric database was done in 2004. This update was based on aerial surveys from 2001 (Manhattan and Staten Island) and 2002 (Bronx, Brooklyn and Queens). This update conformed to the previous database design. In 2006, DoITT formalized the update frequency of the planimetric database and aerial surveys. The aerial photography would be captured on a two-year cycle and the planimetrics a four-year cycle. With the first regularly-scheduled planimetric update to be based on the 2006 aerial photography.
With each subsequent update, refinements have been made. New features and domains have been added, obsolete features have been removed, features are captured in three dimensions, a seamless database is produced and the time between aerial capture and delivery of planimetrics shortened.
Year of Update
A lot of work goes in to producing the planimetrics. The orthophotography takes from nine to twelve months to deliver. A spring capture in 2014 is therefore delivered in 2015. The planimetric features themselves also take from nine to twleve months. All of this is a long way of explaining why data from 2014 is published in 2016. It takes time.
For the 2014 update, additional refinements were made. Skybridges were captured as separate features (sub type within building footprints). Below is an example of a skybridge connecting 3 and 4 MetroTech Center, Brooklyn.
Previous (2010) and current (2014) representation of skybridges.
Cooling towers are a new feature capture – see example below. This data will be published in the next couple weeks.
Curblines are a new separate feature. Previously curblines were a subtype in Pavement Edge. Pavement Edge features were segmented at the apex of each edge and a unique ID was assigned. These IDs were then transferred to the Citywide Centerline.
As with the previous update, all of the individual data sets are on the open data portal. New with this update is a comprehensive database that contains all of the data sets. Additionally, the data were tagged with ‘planimetrics’ and ‘doitt gis’ to simplify search and discovery. Lastly, previous blog posts will be updated with any new or updated data urls. Happy mapping!