The District of Columbia

GSA Federal Locations (GSAPt)

GSA Federal Locations (GSAPt)

by General Services Administration on 01/27/2006

Keywords
About: Federal, Office, Facility, Agencies, Locations, society, Government, GSA
Taking place at: Washington, D.C., District of Columbia, DC, DC GIS, DCGIS

Abstract

GSA (General Service Administration) locations. The dataset contains locations and attributes of GSA owned or leased buildings, created as part of the DC Geographic Information System (DC GIS) for the D.C. Office of the Chief Technology Officer (OCTO) and participating D.C. government agencies.

A database provided by GSA identified Federal locations and DC GIS staff geo-processed the data.

All DC GIS data is stored and exported in Maryland State Plane coordinates NAD 83 meters.

METADATA CONTENT IS IN PROCESS OF VALIDATION AND SUBJECT TO CHANGE.

Purpose

This data is used for the planning and management of Washington, D.C. by local government agencies.

Access constraints

Contact OCTO GIS. Any data obtained outside of OCTO GIS are unauthorized copies.

Use constraints

Acknowledgment of the DC Geographic Information Systems Program (DC GIS). The District of Columbia Government makes no claims as to the completeness, accuracy or content of any data contained hereon, and makes no representation of any kind, including, but not limited to, the warranty of the accuracy or fitness for a particular use, nor are any such warranties to be implied or inferred with respect to the information or data furnished herein.

Point of contact

GIS Data Coordinator
in D.C. Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

fax: (202) 727-5660
hours: 8:30 am - 5 pm

Credits

General Services Administration (GSA)

Data accuracy

Accuracy
Data believed to be complete and accurate, subject to change. Digital version compared with original source data for accuracy and completeness. Validated by source and/or responsible agency.

Logical consistency
In process of validation by source and/or responsible agency.

Completeness
Data believed to be complete and accurate, subject to change. Digital version compared with original source data for accuracy and completeness. Validated by source and/or responsible agency.

Horizontal positional accuracy
In process of validation by source and/or responsible agency.

Vertical positional accuracy
N/A

Lineage / Sources

  • GSA website
    website, locations and attributes
    General Services Administration (GSA)
    by GSA, 05/19/2003
Lineage / Processes
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer



fax: (202) 727-5660
hours: 8:30 am - 5 pm

Data Collection:

Through the application's functionality and usability requirements, OCTO GIS staff compose a list of data layers needed for the application. From this, staff determine the appropriate source and location for each layer, and assess the effort needed to get it.

Some layers, already part of the DC Atlas, are incorporated into the data store. For DC agency data, agency liaisons ask DC personnel about data availability and acquisition. For third-party data, OCTO-GIS evaluates options and either finds alternatives, purchases, or licenses the data. In some cases, staff create data from existing sources and then add required attribution.
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer



fax: (202) 727-5660
hours: 8:30 am - 5 pm
Data Preparation:

After the collection, the data team prepares the data for qa/qc and inclusion in the data store. This step involves: 1.) configuring the datasets into a common form; 2.) geocoding tabular data using a common address base; 3.) generating or converting paper documents into digital format; 4.) populating required fields; and 5.) resolving data duplication and conflicts.

For geocoding, staff use a derivative of the Office of Tax and Revenue (OTR) owner-point database and the District Department of Transportation's (DDOT) street inventory system (SIS) street centerline file as the address base. Through automated procedures on the owner-point derivative file, personnel clean and standardize the irregular premise address information into street number, name, type, and quadrant fields. Also, staff use the merged SIS file containing the five centerlines classifications (street, alley, drive, service road, and ramp).

First, staff match tabular data to the standardized owner-points. Then, the rest are matched to the street centerline file. After this, staff compose a list of the unmatched records needing further research. Since not all of the records geocode, staff note the final matching figures (number of hits, rejects, and the total).

For web links, team members check the validity of existing links and find matching web sites that directly represent the feature. Staff use several web search engines to find appropriate web links. DC government sites are primarily used, when available.

To eliminate data redundancy, staff identify possible conflicting layers and duplicate features. In some cases, staff pick the best source. In others, the attributes in the multiple layers are consolidated. Sometimes, staff map the conflicting layers and investigate feature clusters as areas of potential duplication.

Where applicable, team members move points to the center of the corresponding buildings. Staff then select the building footprints and assign the appropriate GIS_ID value that links the points with the appropriate building polygon(s).
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer



fax: (202) 727-5660
hours: 8:30 am - 5 pm

Data QA/QC

After data preparation, the data team performs qa/qc. Various processes check the following parameters: 1.) spatial and attribute accuracy; 2.) data usability; 3.) data dictionary adherence; 4.) specialized metrics, such as connectivity and directionality; and 5.) data load success. These checks are, as follows:

Visual - staff perform a structured visual check of the data, using on-screen, plotting, and customized routines, and, at times, comparing it to the source documents.

Edge-matching - For grided datasets, staff review the spatial capture, connectivity, and attribution of data across tile boundaries, where applicable.

Automated - Staff compare the data to documented standards and source files through automated procedures and reports.

Specialized - Staff review more specific data parameters, such as directionality, connectivity , and topology.

Edit Verification - Staff ensure that previous errors are fixed to specifications.
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Field Verification - Occasionally, through field work, team members compare the GIS data with the real world.

Data Loading - Staff evaluate the success and evaluate the process of loading raw data into a structured database.

Since most of the data use addresses as the spatial reference, staff compare the data against base layers (buildings, roads, street centerlines, owner-points, parks, and orthophotography) and move features where needed.

In some cases, OCTO GIS personnel produce maps and reports for source agency review. Through an iterative process, staff modify and enhance the layer to agency specifications. For some datasets, the agency endorses the final product for data load and publication.
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer



fax: (202) 727-5660
hours: 8:30 am - 5 pm

Final Data Preparation:

For final preparation, staff ensure all of the needed items are present (unneeded items are deleted), the metadata is complete and current, the shapefile is in the proper projection, and a spatial index exists. If not already done, a GIS_ID (unique id for features in the layer) is computed with automated tools.
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer



fax: (202) 727-5660
hours: 8:30 am - 5 pm

Data Load:

After final preparation, OCTO GIS staff load the data into the application's test database, where SDE handles the spatial data and ORACLE manages the attribute information.

First, staff add primary key and name fields to the layer. Second, personnel register the layer into the appropriate tables and establish the unique feature-ids (the link between the spatial object and its attributes) specific to that layer. Then, staff populate feature, search, address, web url, contact, data source, and other tables, where applicable. For point layers, team members calculate each feature's geographic extent and populate the features table. Lastly, each layer is intersected with the base geography (2002 Advisory Neighborhood Commission areas, 2002 wards, zip codes, neighborhoods, and neighborhood clusters) to populate the "what's-within" tables for the web reports. Views are refreshed when needed.
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer



fax: (202) 727-5660
hours: 8:30 am - 5 pm

Data Load QA/QC

OCTO GIS performs spatial checks comparing the test SDE database with source files to check for completeness, spatial integrity, and proper attribution. First, staff compare the test database contents with documented standards. Then, team members check the geography and attribution, as well as compare dataset parameters between both layers.

The data team performs attribute checks on the ORACLE database to ensure the existence and validity of views. Again, staff compare the database contents with documented standards. For critical views, personnel check the view structures and data against source files and documentation.
GIS Data Coordinator
in Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

fax: 202-727-5660
hours: 8:30am - 5:30pm
Staff updated the federal locations from data provided on the GSA website. Addresses were geocoded against the Master Address Repository from May 2005. Addresses that did not geocode were placed visually using the planimetrics, 2002 orthophoto, and MAR address points. Data was QC'd to check for incorrect geocoding results.

GSA offices include those that are lease or owned by GSA. In most of the leased locations, GSA leases a portion of the entire office building.
Dataset copied.
Staff updated the federal locations from data provided on the GSA website. Addresses were geocoded against the Master Address Repository from December 2005. Addresses that did not geocode were placed visually using the planimetrics, 2002 orthophoto, and MAR address points. Data was QC'd to check for incorrect geocoding results.

GSA offices include those that are lease or owned by GSA. In most of the leased locations, GSA leases a portion of the entire office building.

Distribution

Most DC GIS datasets can be downloaded from "http://dcgis.dc.gov" on the data center page. Orders can also be made by contacting OCTO GIS at "dcgis@dc.gov", especially for datasets not available for download.

Distribution liability
Acknowledgment of the DC Geographic Information Systems Program (DC GIS). The District of Columbia Government makes no claims as to the completeness, accuracy or content of any data contained hereon, and makes no representation of any kind, including, but not limited to, the warranty of the accuracy or fitness for a particular use, nor are any such warranties to be implied or inferred with respect to the information or data furnished herein.

Distributed by
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

fax: (202) 727-5660
hours: 8:30 am - 5 pm

Entity

DCGIS.GSAPt

Attributes

  • ALIAS
    Alternate Building Name
  • SHAPE / ESRI
    Feature geometry.
  • OWNERSHIP
    Owned or Leased
  • Shape / ESRI
    Feature geometry.
  • WEBURL
    WEB URL
  • NUM
    Numeric GSA building id
  • BLDG_NAME
    Building name
  • ADDRESS
    Physical location address
  • HSR
    Historic site
  • GIS_ID
    OCTO-GIS sequential ID
  • GSAAREA
    Area of Building (only for owned buildings)
  • OBJECTID / ESRI
    Internal feature number.

Metadata

FGDC Content Standards for Digital Geospatial Metadata / FGDC-STD-001-1998 as of 06/26/2008

Provided by
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

fax: (202) 727-5660
hours: 8:30 am - 5 pm