Description: Taxiway, Apron: Delineate footprint of the following features. A taxiway connects aircraft to other areas and facilities of an airport. The apron is an area of an airport where aircraft are parked, unloaded or loaded, refueled, or boarded.Airport/Heliport Perimeter: Delineate the full perimeter of the airport or heliport.Helipad: Delineate clearly marked hard surface landing area or platform for helicopters.
Copyright Text: Office of the Chief of Technology Officer
Description: Building structures include parking garages, ruins, monuments, and buildings under construction along with residential, commercial, industrial, apartment, townhouses, duplexes, etc. Buildings equal to or larger than 9.29 square meters (100 square feet) are captured.Buildings are delineated around the roof line showing the building "footprint." Roof breaks and rooflines, such as between individual residences in row houses or separate spaces in office structures, are captured to partition building footprints. This includes capturing all sheds, garages, or other non-addressable buildings over 100 square feet throughout the city. Atriums, courtyards, and other “holes” in buildings created as part of demarcating the building outline are not part of the building capture. This includes construction trailers greater than 100 square feet.Memorials are delineated around a roof line showing the building "footprint."Bleachers are delineated around the base of connected sets of bleachers.Parking Garages are delineated at the perimeter of the parking garage including ramps. Parking garages sharing a common boundary with linear features must have the common segment captured once. A parking garage is only attributed as such if there is rooftop parking. Not all rooftop parking is a parking garage, however. There are structures that only have rooftop parking but serve as a business. Those are captured as buildings.Fountains are delineated around the base of fountain structures.
Copyright Text: Office of the Chief of Technology Officer
Description: Bridges: All bridges are digitized as polygons. Bridges carry roads or railroads over water. Outside edges of all bridges delineated. Also bridge deck locations or clear spans where deck is not visible. This includes all overpasses (bridges that carry traffic over roads or railroads) and underpasses. Outside edge of all overpasses delineated. Bridges overlap road polygons. Pedestrian bridges are not captured.Tunnel Entrances: Entire tunnels are not captured, but all entrances to a tunnel are captured as polygons illustrating the width of the tunnel. Polygons plotted around tunnel openings and any abutments or walls which identify the tunnel entrance. Hidden Bridges: Hidden bridges are features that run under other features such as other bridges, overpasses, or tunnels and are not fully visible in an aerial photograph. The locations are interpreted based on the information visible on either side of the bridge.
Copyright Text: Office of the Chief of Technology Officer
Description: Curb: The edge of roads, alleys, ramps or parking lots, other than those for which polygons can be formed. Curbs are rims, usually made of concrete, along a roadway, forming an edge for a sidewalk. Curbs do not occur where the sidewalk meets the road, such as at wheelchair or access ramps, and driveways.Hidden Curb: Hidden curbs are depicted where curbs cross beneath underpasses or through tunnels. The location of these features are inferred.
Copyright Text: Office of the Chief of Technology Officer
Description: Control points are captured by land surveyors to create control for orthophotography. These points are captured with survey-grade equipment ensuring the highest accuracy in their location.Horizontal Control Point: Surveyed horizontal geodetic control points that are used in the development of an analytical aerotriangulation solution.Vertical Control Point: Surveyed vertical geodetic control points that are used in the development of an analytical aerotriangulation solution.
Copyright Text: Office of the Chief of Technology Officer
Description: Grate: A single point capture for the feature at the visual center point. Grates are structures of parallel or crossed bars, used to cover steam vents or other ventilation features for buildings, and also include grates for DC Metro ventilation. They typically occur on sidewalks. Stormwater inlets are not included.
Copyright Text: Office of the Chief of Technology Officer
Description: Obscured Areas are areas in the compilation imagery that due to shadows, dense vegetation, heavy tree cover, building lean, etc., that completely block out all image detail and nothing can be seen or interpolated to meet accuracy or project scope. Since these areas are obscured by shadows, the level of confidence in the placement of the bounding lines is reduced.
Copyright Text: Office of the Chief of Technology Officer
Description: This layer contains hydrography such as streams, rivers, and other linear hydrography features. Hidden hydrography, inferred drainage connectors, or culverts connect visible hydrography to form a continuous network. These connectors or hidden features maintain a predictable direction connecting the 2 points that conceal or infer the feature.Streams: Captured as single line if less than two meters wide. Both water edges plotted if wider than two meters.Docks and Piers: Visible outline delineated.Jetty: Visible outline delineated.Seawall: Single line plotted at the face of the seawall.Hidden Hydrography: Hidden hydrography is not obvious, even to someone standing under a bridge for example; it cannot be seen photogrammetrically and can be captured only from other sources. Segments of rivers, streams, and canals that flow under features such as bridges and roads are captured as continuous portions of the river, stream, or canal.
Copyright Text: Office of the Chief of Technology Officer
Description: The perimeter of all public and private sport/recreation courts, including clay, grass, dirt, and paved surfaces are captured. Each court is delineated separately even if adjacent. Pavement around the recreation court is captured as sidewalk, not recreation court. Courts are defined as:Basketball Court: full outline of the court Tennis Court: full outline of the courtBaseball Field: infield and outfield of a baseball area as one polygon if easily defined in aerial photo. Otherwise infield as the baseball field.Football Field: full outline of the field as best defined in aerial photoSoccer Field: full outline of the field as best defined in aerial photoTrack: outline of track. Any recreation fields within tracks are captured and coded separately.Other Recreation Area: For areas that cannot be easily defined by function, they are captured as other recreation area, with full outline of the field as best defined in aerial photo.
Copyright Text: Office of the Chief of Technology Officer
Description: Centerlines of railroads or Metrorail are captured. The line is at the midpoint between each rail line. Hidden features due to tunnels, overpasses, or bridges are interpolated for connectivity. These areas are attributed as hidden railroad features.Railroad Centerline: Delineated centerline between all dual-rails, including marshaling yards.Metro Railroad Centerline: Delineated centerline between all Metrorail dual-rails, including marshaling yards.Streetcar Railroad Centerline: Delineated centerline between all streetcar dual-rails, including marshaling yards.Hidden Railroad: Captures the centerline of railroads that are obscured by overpasses or tunnels. The location of these features is inferred.
Copyright Text: Office of the Chief Technology Officer
Description: Road edges are defined as the edge of the improved surface including the improved shoulder but do not include the unimproved shoulder, only the travel part of the road. The road network is compiled to include all open intersections. Features do not overlap sidewalks, but have the sidewalk area cut out of the road polygons. Overlapping features are acceptable if one of the features is hidden.Road: A generally named thoroughfare, that is usually paved and can be public or private. Unimproved thoroughfares are excluded. Road polygons are formed by a combination of road edge, curb, sidewalk, street intersection closure line, and map sheet edge.Paved Median Island: Perimeter of non-traffic paved areas that separate traffic lanes in opposing directions. Unpaved Median Island: Perimeter of non-traffic grassy, unpaved areas that separate traffic lanes in opposing directions. Paved Traffic Island: Perimeter of non-traffic concrete areas in the middle of streets designed to segregate traffic flow. This does not include linear barriers, e.g., Jersey barriers, walls or guardrails, or point barriers, such as impact attenuators. Features do not overlap sidewalks.Unpaved Traffic Island: Perimeter of non-traffic unpaved, grassy areas in the middle of streets designed to segregate traffic flow. This does not include linear barriers, e.g., Jersey barriers, walls or guardrails, or point barriers, such as impact attenuators. Features do not overlap sidewalks.Alley: Perimeter of alleys first plotted photogrammetrically from other indicators such as building footprints, fence lines, curb lines, walls, paved or unpaved drives, and map sheet edge. Alley polygons are closed along the lines where they intersect with road polygons.Paved Drive: A paved driveway for a building or entranceway for a parking lot. Driveways are neither streets nor alleys, but provide access to public facilities, such as a drive to a monument, museum, hotel, large estate, sports field or golf course, grounds of the U.S. Capitol, etc. If a driveway is less than 200 feet and leads to a parking lot, the entire paved area is captured as Parking Lot. Driveways are photogrammetrically compiled as polygons and not compiled from individual vectors on different levels. Parking Lot: Generally paved surfaces used for cars to park on. Paved drives usually form entrances to these features, if the drive is more than 200 feet. If the driveway is less than 200 feet leading into the parking lot, the entire paved area is captured as Parking Lot. Parking lots sharing a common boundary with linear features must have the common segment captured once, but coded as both polygon and line. Small parking areas, where individuals park their cars in the middle of a block off a public alley, are not captured as parking lots. These are either public space (e.g., alleys) or private space where owners permit parking to occur.Intersection: A location where more than one road comes together. For standard cross streets, intersection polygons are bounded by curbs and four closure lines at street intersection crosswalks (outer line) or placed arbitrarily where crosswalks could logically be placed. For "T" intersections, the polygons are bounded by curbs and three such closure lines. Complex intersections can have more closure lines. Entire traffic circles are coded as intersections.Hidden Road: A section of a road that passes underneath a bridge or overpass and is not visible in an aerial photograph, but the location can be interpreted based on the road on either side of the bridge.Hidden Median: A road median that exists underneath a bridge or overpass and is not fully visible in an aerial photograph, but the location can be interpreted based on the information visible on either side of the bridge.
Copyright Text: Office of the Chief of Technology Officer
Description: All public walkways are captured. Sidewalks do not overlap other feature classes unless they are hidden under a bridge or overpass. Cement pads around public swimming pools are captured. Walkways in common areas of apartments, college campuses, and business parks are captured as sidewalks. Individual resident sidewalks are not captured.Sidewalk: Sidewalks either compiled photogrammetrically as polygons or derived from a combination of vectors including: curbs, buildings, walls, driveways, or other features. Any stair feature that is less than 5 stairs is coded as sidewalk to maintain continuity.Hidden Sidewalk: Sidewalks that are obscured by overpasses or tunnels. They are not fully visible in an aerial photograph, but the location can be interpreted based on the information visible on either side of the bridge.Stairs: Groups of 5 or more stairs outside of major buildings or monuments, as well as part of sidewalks. Individual stairs are not captured. If landings exist within stairs, they are captured as sidewalk, not stairs.Crosswalk: Marked crosswalks that are fully visible in an aerial photograph.
Copyright Text: Office of the Chief of Technology Officer
Description: The perimeter of public and private swimming pools are captured, for both above-ground and in-ground pools. No other features can make a side for this feature. Pools do not overlap any other feature class. Pool decks and pavement around pools is not captured as a pool. Pavement around pools is captured as sidewalk. Roof-top pools are not captured.
Copyright Text: Office of the Chief of Technology Officer
Description: Traffic Barrier. The dataset contains polylines representing planimetric traffic barriers, created as part of the DC Geographic Information System (DC GIS) for the D.C. Office of the Chief Technology Officer (OCTO). These features were originally captured in 2015 and updated in 2017, 2019, and 2021.
Copyright Text: Office of the Chief Technology Officer
Description: Water is a polygon feature class consisting of the following features and capture rules:Lakes, Reservoirs: Delineates the shoreline of all standing bodies of water designated as a lake or reservoir.Ponds: Delineates the outline of all standing bodies of water designated as ponds. Includes man-made ponds over 100 square feet.Rivers: Captures the banks of all flowing bodies of water two meters wide or wider, i.e., rivers.Pools: Captures the outline of the water portion of fountains and codes them as pools.
Copyright Text: Office of the Chief of Technology Officer