Metadata: Building Footprints

Building Footprints

Category Building
Feature Dataset Name STAND-ALONE
Item Name Building_Footprints_pdx
Database Type SDE
Originator City of Portland
Bureau Bureau of Planning and Sustainability
Publication Date 01/01/1996
Abstract Regional building footprints. Original buildings are constructed of multiple "polygons" representing the different building heights. All polygons making up a single building have the same "building ID" [Bldg_ID], which was used to dissolve the buildings into generalized building footprints. Attributes that apply to the entire building were retained.
Purpose For mapping generalized building footprints, i.e., cartographic base maps.
Supplemental Information Portland Central City, Lloyd District, Central Eastside, and OHSU all mapped by the Bureau of Planning and Sustainability using photogrammetric data and aerial photos. Buildings constructed after 2007 are derived from building permit information and aerial photos. All other buildings are derived from 2004 to 2007 LiDAR data. All elevation and height data are in US Survey feet.
Last Dataset Update 08/16/2019 17:34
Last Source Update 08/15/2019 20:13
Maintenance/Update Frequency Continually
Extent Clackamas County, Multnomah County, and Washington County, Oregon
Data Type Vector
Shape Type Polygon
Feature Count 725622
Horizontal Position Accuracy Horizontal Accuracy: Original building footprints have been modified to more accurately register with taxlots where appropriate. Overall horizontal accuracy is unknown. Buildings derived from LiDAR should have a horizontal accuracy of +/- 2'. Vertical Accuracy: Elevations and heights derived from photogrammetric data are within +/- 2' in most cases. Heights derived from LUR information or 3D models should be precise. Heights derived from LiDAR data are generally within +/- 15cm (~6") for buildings not obscured by vegetation, +/- .7m (~2.5') where buildings are covered by vegetation. Heights derived from field laser-range finder measurements are usually within +/- 7'. Some building heights have been estimated using aerial photos or field visits. The accuracy of estimated elevations and heights are unknown. Surface elevations derived from LiDAR data are generally within +/- 15cm (~6") for relatively flat areas not obscured by vegetation, +/- .7m (~2.5') where in areas of steep slopes or surfaces covered by vegetation. Surface elevations derived from the 2001 DEM are within +/- 5' in most cases.
Horizontal Position Accuracy Link Taxlots
Progress Complete
North Bounding Coordinate 782458.349871687
South Bounding Coordinate 452262.018156424
East Bounding Coordinate 7891193.25314777
West Bounding Coordinate 7463899.96243644
Theme Keyword(s) footprint, building, buildings, outline
Theme Keyword Thesaurus None
Place Keyword(s) Portland, Multnomah County, Washington County, Clackamas County, Oregon
Place Keyword Thesaurus None
Access Constraints Available for Public Use
Use Constraints These data are distributed under the terms of the City of Portland Data Distribution Policy. Care was taken in the creation of this data but it is provided "as is".

The City of Portland cannot accept any responsibility for errors, omissions, or positional accuracy.
Source Dataset Type File Geodatabase
Output Geodatabase EGH_PUBLIC.GDB
Distribution Grid: State plane coordinate system 1983(91).
Units: International feet
Datum: North American Datum of 1983/1991 (HPGN)
Liability: The information in this file was derived from digital databases on the City of Portland GIS. Care was taken in the creation of this file. The City cannot accept any responsibility for errors, omissions, or positional accuracy. There are no warranties, expressed or implied.
Format: Shapefile or File Geodatabase Feature Class - Data will be provided via City of Portland FTP Site.
Online Resource: http://portlandmaps.com/opendata
Online Instructions: City of Portland Public/Open Data is distributed via the PortlandMaps Open Data Site - http://portlandmaps.com/opendata. Data not available on the PortlandMaps Open Data site can be requested by contacting the City of Portland CGIS Group - maps@portlandoregon.gov
Transfer Size: varies
SPCS Zone Identifier: 5076
Contact(s)
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Kevin Martin
503 823-7710
503 823-7800
kevin.martin@portlandoregon.gov
1900 SW 4th Avenue, Suite #7100
Portland, OR 97201

City of Portland - BPS
503 823-7700
503 823-7800
bps@portlandoregon.gov
File(s)
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Images
52413.png 59.21Kb X
Lineage
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Buildings in Portland's Central City were originally digitized from photogrammetric data derived from aerial photos flown from 1987 to 1994. Created for the Bureau of Environmental Services. Not registered directly to the Taxlot Base Maps. New Central City buildings since 1994 were manually digitized using land-use review (LUR) case information submitted as part of the building permit approval process, and, when available, CAD and 3D models provided by the project architects or developers. The 3D models provided by developers were retained with all of their original detail as Sketchup files. These Sketchup files were then used as reference to create the more generalized "massing" models in the 3D buildings GIS dataset. If no case information or 3D model was available, Central City buildings were digitized using 1996 to 2007 aerial photos and/or 2004 to 2007 LiDAR data as reference.

All edits were performed in ArcGIS using a custom ArcMap interface allowing the editor to automatically populate surface and roof elevations/heights and attribute the other database fields. All editing was performed using the standard ArcMap editing tools. All buildings were created as unique, non-overlapping polygons in order to facilitate the conversion to other formats (such as ArcInfo coverages) for modeling and analysis purposes.

Surface Elevations: Derived surface elevation for a point within each building polygon using LiDAR digital elevation models (derived from 2004 to 2007 LiDAR acquisition flights) or, where LiDAR data was not available, a 2001 DEM developed by the Bureau of Planning. Roof Elevation/Height: Roof elevations were derived from the LiDAR first-return points, photogrammetric elevation points, LUR case information, or from 3D models provided by the project architect or developer. If none of this information was available, roof elevations were estimated using laser-range finder measurements or aerial photos. Height was calculated by subtracting the roof elevation from the surface elevation.
Buildings outside Portland's Central City were derived from 2004 to 2007 LiDAR data. The following steps were used to delineate building footprints from the LiDAR data:
  1. MicroStation was used to convert the Lower Columbia 2005 LiDAR point data from its raw asciiformat into LAS files. The projection was transformed from Washington State Plane South toOregon State Plane North. The data did not contain usable pulse return information, so the returnsfield for all points was set to 1/1 and the data was treated as single return.
  2. Rasters were created from 1/100th quad *.las files for ground-classified points for each LiDAR dataset, as well as first and last returns for the PSLC 2007 LiDAR and single returns for the Lower Columbia 2005 LiDAR.
  3. Rasters were imported into LiDAR Analyst and several building and tree models with differentparameters were run to delineate building footprints that would provide an alternative best-fit foreach structure.
  4. The initial polygon output was overlaid on a hillshaded DEM of the bare earth and buildings LiDARraster and manually edited as necessary. The types of manual edits included:
    • Splitting of single polygons covering multiple distinct buildings.
    • Adjustment of polygon edges to more accurately outline buildings or selection ofalternative building footprint model.
    • Rotation of an entire footprint if it was tilted more than 30 degrees from the building?sactual orientation (smoothing and squaring routines within LiDAR Analyst sometimes causea building footprint to ?tilt? on its axis).
    • Deletion of non-building polygons. e. Digitization of building footprints missed by LiDAR Analyst. f. Removal of ?holes? or extraneous structures (HVAC, antennae) within footprint polygons.(Courtyards were not removed.)
  5. Aerial photographs (2008) were laid beneath the building footprint polygons and used for visualverification of building shape. Unless the LiDAR data was completely insufficient for classifying abuilding (e.g., zero returns from a portion or all of a particular building), the footprints were notdelineated from the photographs.
  6. Polygon topology was checked for overlaps, duplicates, and other errors. Edits were applied asneeded.
  7. LiDAR Analyst was used to square up manual edits, and then apply elevation and geometryattributes from the LiDAR data.
  8. LIDAR Analyst *.las point cloud classification routines were used after all polygon edits had beencompleted. A customized script was run to compare the output ground model with the originalmodel delivered to PSLC by Watershed Sciences and remove any new ground-classified points, thusimproving the accuracy of building heights calculated in subsequent steps. Manual declutter inMicroStation removed erroneously classified objects such as trees, and power lines overhangingrooflines.
  9. Building and ground rasters were exported from the classified point cloud at 1.5? resolution (PSLCLiDAR) and 3.0? resolution (Lower Columbia LiDAR).

Buildings constructed since the most recent LiDAR flight are digitized using building permit information as reference (when available). Updates are made as needed, and new permits are updated and reviewed monthly. Geometry is derived from building permit information (site plans) where the building does not already exist, or 6" aerial photos where the building does exist.
As buildings are edited and updated, the Portland building data is combined with the most recent regional building data to create a complete regional set of building data.
Residential units were assigned to buildings using a variety of sources, including building permit information, research of individual buildings, tax assessment information, and Metro's regional multi-family residential inventory. In the case of the latter, which is parcel-based, where there was more than one building on a parcel, units were assigned to buildings based on weighted building square footage.
Building data is dissolved on the unique building ID (Bldg_ID) and a subset of other attributes that apply to the entire building to generate the dissolved building footprints.
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Attribute Tables & Domains

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building_footprints_pdx
Table Description
Table Jurisdiction
Column Sort Column Name Column Alias Column Type Column Size Domain Value(s) Column Description
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1 OBJECTID Numeric 8
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X
A unique ID for each building polygon (generated by the GIS software); these IDs can change.
1 SOURCE Reference Source String 30
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Aerial Photos 6" resolution regional aerial photos.
X
Lidar-Derived Building was digitzed automatically from most recent LiDAR data (2004, 2005, 0r 2007)
X
LUR/Building Permit Land use review or building permit information, including site plans
X
Other Other reference source (see notes)
X
Photogrammetrics Derived from 1990's photogrammetric information.
X
3D Model 3D model provided by developer (usually a SketchUp model)
X
X
The reference source used to map the building (same domain as the HGT_SOURCE attribute)
1 STATE_ID Taxlot State ID String 20
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X
The state ID of the primary taxlot on which the building resides (usually derived from the center of the building polygon).
1 SURF_SRC Surface Elevation Source String 30
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LiDAR DEM Surface elevation derived from a 3' resolution LiDAR surface elevation model generated from 2004 through 2007 bare earth LiDAR point returns. Vertical accuracy is generally within +/- 15cm (~6") for relatively flat areas not obscured by vegetation, +/- .7m (~2.5') where in areas of steep slopes or surfaces covered by vegetation.
X
2001 DEM A 10' resolution DEM generated from a 2001 DTM created from 2001 aerial photos. Surface elevations derived from the 2001 DEM are within +/- 5' in most cases.
X
X
The source information for the surface elevation
1 BLDG_ADDR Building Address String 50
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The building's street address
1 BLDG_NAME Building Name String 150
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The building name (if known)
1 NUM_STORY Number of Stories Integer 2
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The maximum number of building stories (if known)
1 BLDG_SQFT Square Footage Integer 4
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X
The building square footage (if known, usually gross)
1 YEAR_BUILT Year Built Integer 2
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X
The year construction of the building was completed (if known)
1 BLDG_TYPE Building Type String 30
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X
The type of building (house, garage, etc.). Not yet populated. Domain to-be-determined.
1 BLDG_ID Building ID String 30
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The unique building ID. This is the master identifier for the building. These IDs do not change and will not be reused.
1 BLDG_USE Predominant Use String 30
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Commercial General General commercial use
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Commercial Grocery Grocery store or market
X
Commercial Hotel Hotel or motel use.
X
Commercial Restaurant Restaurant or bar use
X
Commercial Office Commercial Office use
X
Commercial Retail Commercial Retail use
X
Industrial Industrial use
X
Institutional Institutional use including hospitals and universities
X
Multi Family Residential Multi family residential use (including condos, apartments, 3 or more unit plexes)
X
Parking Structured parking
X
Single Family Residential Single Family Residential (including ADUs, rowhouses, and duplexes)
X
Vacant Vacant X
X
Predominant building use. Not consistently populated outside Portland's Central City.
1 ROOF_ELEV Roof Elevation Numeric 8
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The maximum roof elevation (above NAVD88 datum) of the building footprint in feet.
1 AVG_HEIGHT Average Height Numeric 8
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The maximum average height of the building footprint in feet.
1 HEIGHT_SRC Height Source String 30
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Aerial Photos Building Height estimated from 6" aerial photos (flown every year) X
Field Estimate Building height estimated in the field (by counting stories, for example). X
Field Measurement Building height estimated in the field using a laser range-finder or other measurement method. X
Inferred from Assessor Sqft Building height inferred from County Assessor square footage. Total assessed square footage is divided by the footprint square footage and the result multiplied by average floor height. Used for single-family buildings only. X
Lidar DSM Building height manually derived from 2004 to 2007 LiDAR first-return "digital surface model" (DSM) X
Lidar-Derived Building heights automatically derived from 2004 to 2007 LiDAR data by Watershed Sciences using the process described in the data lineage section above. X
LUR/Building Permit Building height information derived from documents and plans submitted as part of the land-use review (LUR) and building permit process. X
Oblique Aerials Building height information derived from oblique aerial photos and "street view" photos accessible in Bing, Google Earth, and Google Maps. X
Other Building height information derived from a non-standard source (refer to notes) X
Photogrammetrics Building height derived from photogrammetric data derived from aerial photos flown from 1987 to 1994. X
3D Model Building height information derived from a digital 3D model provided by the developer (usually in SketchUp format). X
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The reference data source used to derive the height and elevation of the building or portion of a building.
1 SURF_ELEV Surface Elevation Numeric 8
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The average surface elevation (above NAVD88 datum) of the land beneath the building footprint in feet.
1 CREATEDATE Creation Date Date 8
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The date that the building was originally mapped (added to the GIS data, if known)
1 MOD_DATE Modification Date Date 8
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The date of the most recent edits to the building footprint (if known)
1 MOD_NAME Modifier Name String 50
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The initials of the person that last edited the building or portion of a building
1 FIELD_DATE Field Date Date 8
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The date of any field visit to the building
1 REVIEW Flag for Review? String 30
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"T" indicates the building or portion of the building needs to be reviewed for mapping and/or height accuracy.
1 NOTES Notes on Building String 150
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Notes and comments related to the building or portion of a building
1 SUBAREA Maintaining Agency String 30
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City of Portland City of Portland maintenance area
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Metro Metro regional maintenance area
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X
Names of regional data-maintenance subareas
1 LAT_CTR Center Latitude Numeric 8
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Latitude of the center of the building footprint
1 LONG_CTR Center Longitude Numeric 8
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Longitude of the center of the building footprint
1 WSUNIQUEID Watershed Sciences ID String 30
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Unique ID assigned by Watershed Sciences for buildings automatically derived from LiDAR (no longer used)
1 BPS_BLDGID City of Portland ID - BPS Integer 4
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Old BPS unique building ID (no longer used)
1 BLDG_NUMB Building Number Integer 2
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The building number. Each building on a single parcel receives a unique number, starting with #1. These numbers are used to construct the unique building ID.
1 SQFT_SRC Square Footage Source String 50
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Source of square footage information
1 STORY_SRC Number of Stories Source String 50
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Source of number of stories
1 STRUC_TYPE Structure Type String 30
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Reinforced Masonry Reinforced masonry construction
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Steel Framed Steel framed construction
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Unreinforced Masonry Unreinforced masonry construction
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Wood Framed Wood framed building
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X
The predominant construction method used to build the structure.
1 STRUC_COND Structure Condition String 30
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Unsafe Structure deemed unsafe by the Portland Fire Bureau
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The general condition of the structure.
1 ROOF_TYPE Roof Type String 15
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Complex Complex structure with no consistent features.
X
Flat Flat roof
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Multi-level Flat Flat roof with multiple levels (portions of the building are different heights)
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Pitched Pitched roof
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X
The basic roof structure type. Automatically populated for all LiDAR-derived buildings, manually populated for other buildings on a case-by-case basis.
1 ORIENT Building Orientation Numeric 8
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The orientation angle of the building along it's longest axis. Automatically populated for all LiDAR-derived buildings, manually populated for other buildings on a case-by-case basis.
1 VOLUME Building Volume Integer 4
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Estimated volume of building (in cubic feet). Calculated by multiplying the footprint area by the average building height.
1 CREATED_BY Created By String 50
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BPS City of Portland Bureau of Planning and Sustainability
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CGIS City of Portland Corporate GIS group
X
City of Beaverton X
City of Gresham X
City of Hillsboro X
City of Lake Oswego X
City of Portland Building created by other City of Portland organization
X
City of Tualitan X
City of West Linn X
Metro X
Oregon City X
PPR City of Portland Parks and Recreation
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Watershed Sciences Building automatically derived from LiDAR by LiDAR consultant Watershed Sciences
X
X
Name of agency that originally mapped the building
1 SOURCE_REF Reference Source Details String 50
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Additional details about the mapping source (e.g., the date of LiDAR data used, the LUR/building permit case number, etc.)
1 MAX_HEIGHT Maximum Height Numeric 8
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The maximum roof height of the building footprint in feet. Consistently populated for LiDAR-derived buildings only.
1 MIN_HEIGHT Minimum Height Numeric 8
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The minimum roof height of the building footprint in feet. Consistently populated for LiDAR-derived buildings only.
1 BLDG_STAT Building Status String 50
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Demolished Demolished building
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Existing Existing building (or under construction)
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Proposed Proposed building (not yet under construction)
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The status of the building
1 UNITS_SRC Units Source String 30
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County Assessor Database Derived from tax asessor information.
X
Developer Unit information received directly from developer..

X
Development Capacity GIS Model Units estimated by BPS buildable lands inventory GIS development capacity model.
X
LUR/Building Footprint Derived from land use review or building permit information.
X
Metro MFR Inventory Units derived from Metro's regional mult-family inventory.
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Marketing Information/Research Source is online research of the building (we googled it).
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X
Source of the residential unit information.
1 UNITS_RES Residential Units Integer 2
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Total number of residential units in the building. Derived from building permit information, tax assessment information, and Metro's regional multi-family inventory. In the case of the latter, which is parcel-based, units are assigned to buildings based on weighted building square footage.
1 OCCUP_CAP Total Occupancy Integer 2
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Maximum building occupancy (where known).
1 OCCUP_SRC Occupancy Source String 50
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Portland Parks Bureau X
Portland Fire Bureau X
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Source of maximum building occupancy information.
1 ADA_ACCESS ADA Accessible? String 5
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"T" indicates the building is ADA accessible (where known).
1 SURF_OFF Surface Offset Numeric 8
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1 SURF_ADJ Adjusted Surface Elevation Numeric 8
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1 PROPKEY IPS Property Key Integer 4
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1 EDIT_STAT IPS Building Editing Status String 50
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1 DATA_SOURCE Feature Data Source String 5
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1 RETIRED_BY Retired Edit Completed By String 50
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1 RETIRED_DATE Retirement Date of Building Date 8
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X