Introduction to the Digital BAS - PowerPoint PPT Presentation


PPT – Introduction to the Digital BAS PowerPoint presentation | free to download - id: 59a167-Mjk2Z


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation

Introduction to the Digital BAS


Title: Presentation Overview Author: Bernadette Jenkinson Last modified by: byrne313 Created Date: 11/15/2006 10:24:40 PM Document presentation format – PowerPoint PPT presentation

Number of Views:18
Avg rating:3.0/5.0
Slides: 29
Provided by: Bernadette52
Learn more at:


Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Introduction to the Digital BAS

Introduction to the Digital BAS
  • What is the MAF/TIGER Database?
  • What is included in the Digital BAS package?
  • What is the difference between Digital BAS and
  • What are some tips for updating the BAS materials
  • How do I return my digital submission to the
    Census Bureau?
  • MTPS and Digital BAS Demo

MAF/TIGER Database
  • Master Address File/Topologically Integrated
    Geographic Encoding and Referencing (MAF/TIGER
  • Rather than having one layer for each feature
    class, all information is stored in a single
  • Database is constructed of nodes, edges, and
  • Each edge can represent the boundary for multiple
  • Place, County, Tract, School District, Voting
    District Boundaries, etc.
  • Changing a place boundary can affect boundaries
    for other geographies

Topological Relationship
Census Tract
Incorporated Place
School District
Integrated Layer
MAF/TIGER Database - Edges
MAF/TIGER Database County Subdivisions
MAF/TIGER Database School Districts
MAF/TIGER Database Voting Districts
BAS Package Materials
  • Letter and Form
  • Contains your username for MTPS bas
  • You do not need to fill out the form when
    responding digitally
  • MAF/TIGER Partnership Software CD
  • Data and Respondent Guide CD/DVD
  • Contains shapefiles for use with Digital BAS and
  • Contains respondent guides for Digital BAS and
  • No Change postcard

Digital BAS
  • Participants use their own GIS to create the
    digital BAS submission file
  • Create change polygons representing the
    difference between local boundaries and the
    Census Bureaus boundaries
  • Attribute each polygon with the required
  • We send out ESRI shapefiles (.shp), but any GIS
    that can read/convert shapefiles may be used
  • It is important to read the Digital BAS
    respondent guide carefully to make sure you
    include all required information

MAF/TIGER Partnership Software - MTPS
  • As an alternative to another GIS software,
    participants may use the Census Bureaus free
    MTPS to create the digital BAS submission file.
  • The MTPS forces the user to include the required
    attribute information for the boundary and
    feature updates.
  • The software handles the data conversion and
    compresses all of the output files together for
    you to create the final digital BAS submission
  • MTPS is appropriate for users who are not
    experienced in GIS or do not have their own GIS

Digital Update Guidelines
  • We cannot accept a local GIS file to replace
    our existing boundary information
  • Must have legal documentation and effective dates
    for all legal boundary changes
  • We must keep record of all changes made for
    reference purposes
  • Topologically integrated database
  • Snap to existing census geography where
  • Use existing census roads, rail, and hydro
    wherever possible (if our river and your river
    differ spatially by 10 feet, snap to our river)

Data Projections
  • Census files are in GCS NAD 83 format and can be
    projected into any local coordinate/projection
  • Most GIS software packages will allow users to
    transform file coordinate systems and projections
  • In ArcGIS, use the Project tool in ArcToolbox

Types of Boundary Updates
  • Annexations Deannexations
  • Boundary Corrections
  • Geographic Corridors Offsets
  • New Incorporations

Other Acceptable Updates
  • Linear Features
  • Point Landmarks
  • Area Landmarks
  • Address Ranges

Annexations and Deannexations
  • These are referred to as legal boundary changes
  • Large change polygons are most likely annexations
  • Change polygons are sometimes not contiguous with
    your boundaries
  • A change to the entitys boundary through a legal
  • Ordinance/Resolution
  • Local law or Court order
  • State level action
  • Must always include the following in lieu of the
    actual legal documentation
  • Effective Date
  • Ordinance/Resolution Number
  • Acreage required for Georgia entities

Annexations and Deannexations (Attribute Table)
  • Must enter the following in the change polygon
    attribute table for each annexation/deannexation
  • Name of the affected entity
  • The effective date
  • The document/authorization number (Ex ordinance
    or resolution )
  • Change type is coded A for annexation or D for

Boundary Corrections
  • Minor fixes to the entity boundaries due to
    drafting or plotting errors.
  • Should follow the general shape of the current
  • Are neither annexations nor deannexations,
    although they may be fixing the depiction of
    previous annexations or deannexations.
  • Boundary corrections DO NOT require legal

Boundary Corrections (Attribute Table)
  • Must enter the name of the affected entity in the
    Name field
  • Enter B in the Change Type field to designate a
    Boundary Correction
  • In the Relate field enter the following
  • IN if the territory needs to be in the affected
  • OUT if the territory needs to be out of the
    affected entity

Geographic Corridors
  • An area that only includes road surface and
    right-of-way and does not contain any structures
    addressed to either side of the road.
  • The Census Bureau will geocode addresses based on
    the centerline of road.
  • There are two types of geographic corridors
  • 1.) Road through unincorporated space
  • 2.) Road through incorporated space
  • BAS participants should recommend the creation of
    a geographic corridor ONLY when this coding would
    result in addresses being assigned to the wrong

Geographic Corridors
Example Road through an unincorporated place In
this example, the houses are in unincorporated
county, while the road ROW has been annexed into
an incorporated place. Without a corridor, the
housing units along this road would be included
in the incorporated place.
Geographic Offset
  • An area claimed by an entity that is only on one
    side of the road and does not include any
    structures addressed to the right-of-way on that
    side of the road.
  • Policy towards Geographic Offsets
  • We prefer that you do not show a boundary on a
    front lot line.
  • If houses on the far side of the road should be
    in your jurisdiction, please represent the
    boundary on the rear lot line.
  • If houses on the far side of the road should NOT
    be in your jurisdiction, please snap the boundary
    to the centerline.
  • An offset should be used if you must show the
    boundary on the front lot line.
  • Using one of these techniques insures that the
    residential structures will be assigned to the
    correct geography.

Geographic Corridors and Offsets Incorporated
We prefer that you snap the boundary to the
centerline as offsets are difficult to maintain.
If offsets are not coded as such, your boundary
will be snapped.
New Incorporations
  • For all new incorporations, we need the
  • The official name of the new incorporation
  • The name and phone number of a contact person for
  • A copy of the official papers of incorporation
  • The effective date
  • The mailing address
  • The name of the HEO of the new incorporation
  • The name of the BAS contact of the incorporation,
    if different from the HEO

Street Features
  • Street features can be added or edited in MTPS or
  • These are not required unless they serve as a

Data Dictionary
Reporting the Data to the BAS
  • Compress your change polygon shapefile and any
    other edited shapefiles into a zip file
  • If you are using MTPS, the software will
    automatically zip the required shapefiles after
    you are done.
  • Upload the zip file onto the Census Bureaus FTP
  • Instructions for the site are provided in the
    Respondent Guides.
  • The MTPS submission file can be quite large. If
    you are having issues uploading the file onto the
    FTP site, simply remove all the files that do not
    contain the BAS prefix in the name, and try
    uploading again.

Digital BAS Demonstration ArcGIS MAF/TIGER
Partnership Software (MTPS)