Building roofprints delineated from 2020 ortho-imagery by the Denver Regional Council of Governments (DRCOG) and supplemented by Jefferson County.

DRCOG CAPTURE CRITERIA: Building roofprint polygons captured by DRCOG were stereocompiled in 3D. Outlines of permanent, visible structures were captured at the corners of the roof (eave), for buildings with area greater than or equal to 48 square feet and over 5 feet in height. Arms and indentations captured were 2.5 feet or greater. Canopies, carport covers, and sheds are included. For multi-level commercial and/or industrial buildings, each level was captured as a unique record if the building was greater than or equal to 1000 square feet and the multi-level roof levels were greater than or equal to 400 square feet in area and over 5 feet in height. Each polygon is a separate record, where polygons that are part of the same building have the same building ID. On pitched roofs, the highest point is used to determine the building height. The lowest point is the common lowest point if the building is multi-level.

EXTENTS: The DRCOG data capture was constrained to areas for DRCOG's associated LiDAR capture. In Jefferson County, DRCOG did not capture structure roofprints for most of Pike National Forest (PNF) including communities like Buffalo Creek, Longview, Dome Rock and Trumbull, nor for private inholdings with structures within PNF. Consequently, nearly 1,000 structure roofprints in the PNF area were digitized by Jefferson County BIT staff, in August, 2022, using DRCOG 2020 DRAPP ortho-imagery.

ATTRIBUTION: Important columnar attribution includes a unique column identifier (BUILDING_ID), structure height, in feet (BLDG_HEIGHT), ground elevation, in feet above sea level (GROUND_ELEVATION), building type (BLDG_TYPE) with a domain of 'Residential', 'Commercial', 'Industrial', 'Medical', 'Public', 'Garage/Shed', 'Parking Structure', 'Tank', 'Foundation/Ruin', or 'Miscellaneous', and data source (SOURCE), with a domain of 'DRCOG' or 'JEFFCO'. Building addresses are available for project partners through BuildingFootprintsUSA or by overlaying Jefferson County's address data, for County "MasterAddress" features west of the Dakota Hogback / STATE HWY 93, as County addresses in that area were QA'd for their spatial location relevent the associated residential, commercial, industrial, or public structure roofprint, else re-attributed as vacant land (MasterAddress column ADRTYPECODE) where necessary. In addition, nearly 600 DRCOG roofprint features were corrected, as necessary, for building type (column BLDG_TYPE). Note features digitized by Jefferson County have a BUILDING_ID of 3,000,000 or higher, where only BLDG_TYPE and SOURCE were atttributed, given structure height was unavailable and ground elevation, per the County's USGS 10-meter DEM data, was not ascertained.

CHANGE FEATURES: This dataset was an update to previously collected data. Features were originally delineated from 2014 aerial imagery, updated in 2016, 2018, and then again in 2020 in the creation of this dataset. Examples of change that are captured include but are not limited to: new features, change in attribution, and modifications that reach or exceed the threshold for initial collection of this feature. Additions refer not only to truly new features in the built environment but also to features that were added based on a larger extent of capture. Please refer to extent shapefiles for 2014, 2016, 2018, and 2020 feature captures prior to performing change analysis. DRCOG modifications were marked even if only a small portion of the feature changed. A separate change layer is available containing only those features delineated in 2020.

SOURCE DATA: This feature was compiled from DRCOG 2020 Denver Regional Aerial Photography Project (DRAPP) imagery. This imagery is 4-band RGBIR color orthoimagery with a GSD (Ground Sample Distance) of 0.5 foot for 3-inch imagery, 1 foot for 6-inch imagery, and 2 feet for 12-inch imagery. Imagery was collected in the spring with a Vexcel Ultracam Eagle aerial sensor. Imagery is projected in the State Plane Coordinate System, Colorado Central Zone using the Lambert Conformal Conic map projection parameters. Horizontal and vertical datums are NAD83(11) and NAVD88(GEOID12A), respectively. Per County standard, data was projected to Colorado State Plane Grid Coordinates, Colorado Central Zone, NAD83.