Assessor Blocks

Metadata also available as

Frequently-anticipated questions:


What does this data set describe?

Title: Assessor Blocks
Abstract:
This dataset is a representation of each Assessor Block in the City and totals 5,237 records. Each block is comprised of one or more subdivision lots.
  1. How should this data set be cited?

    Department of Public Works, March 2001, Assessor Blocks.

    Online Links:

    • Server=tisent20; Service=5151; User=sfgis; Version=SDE.DEFAULT

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -123.113714
    East_Bounding_Coordinate: -122.355778
    North_Bounding_Coordinate: 37.930881
    South_Bounding_Coordinate: 37.691039

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: April 28, 2004
    Currentness_Reference: publication date

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • G-polygon (5324)

    2. What coordinate system is used to represent geographic features?

      The map projection used is Lambert Conformal Conic.

      Projection parameters:
      Standard_Parallel: 37.066667
      Standard_Parallel: 38.433333
      Longitude_of_Central_Meridian: -120.500000
      Latitude_of_Projection_Origin: 36.500000
      False_Easting: 6561666.666667
      False_Northing: 1640416.666667

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000512
      Ordinates (y-coordinates) are specified to the nearest 0.000512
      Planar coordinates are specified in survey feet

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Resolution: 1.000000
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    SDE.SFGIS.SFBLOCKS
    San Francisco City Blocks (Source: DTIS)

    OBJECTID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    BLOCK_NUM
    Assessor Block Number (Identifier) (Source: DTIS)

    Range of values
    Minimum:0001
    Maximum:9900

    SHAPE
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    SHAPE..Area()
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    SHAPE..Length()
    Feature Geometry (Source: ESRI)


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Dept. of Public Works

  3. To whom should users address questions about the data?

    City and County of San Francisco Department of Telecommunications
    875 Stevenson St. 5th Floor
    San Francisco, CA 94103
    USA

    415-554-0800 (voice)
    415-554-0886 (FAX)
    gis@sfgov.org

    Hours_of_Service: 8:00 AM - 5:00 PM


Why was the data set created?

One of the key basemap layers, the City Blocks SDE Layer can be used to show the City's official Rights of Way. For the most part, the Block boundaries correspond with the right of way, as designated by DPW's Bureau of Street-Use & Mapping.


How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)

  2. How were the data generated, processed, and modified?

    (process 1 of 2)
    In AutoCAD, Right-of-Way lines and Block Number designations were derived from DPW's Grade Maps and the Assessor's Block Maps. The linework and identifying centroids were converted into a LOTS ArcInfo coverage, which contained a BLOCKS region. Those regions were converted into shapefiles and merged together. At ArcGIS 8.1, those shapefiles were moved into SDE format.

    Person who carried out this activity:

    Jeff Johnson
    DTIS

    (process 2 of 2)
    Metadata imported.

    Data sources used in this process:

    • C:\Documents and Settings\jjohnson\Desktop\metadata\sfblocks.xml

  3. What similar or related data should the user be aware of?

    , City Blocks.


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    none

  2. How accurate are the geographic locations?

    none

  3. How accurate are the heights or depths?

    none

  4. Where are the gaps in the data? What is missing?

    none

  5. How consistent are the relationships among the observations, including topology?

    none


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: none
Use_Constraints: none

  1. Who distributes the data set? (Distributor 1 of 1)

    City and County of San Francisco Dept. of Telecommunications
    c/o Jeff Johnson
    Senior Application Developer
    875 Stevenson St. 5th Floor
    San Francisco, CA 95103
    USA

    415-554-5909 (voice)
    415-554-0886 (FAX)
    jeff.johnson@sfgov.org

    Hours_of_Service: 8:00 AM - 5:00 PM
  2. What's the catalog number I need to order this data set?

    City and County of San Francisco, Dept. of Telecommunications and Information Services

  3. What legal disclaimers am I supposed to read?

    The City and County of San Francisco does not guarantee the accuracy, adequacy, completeness or usefulness of any information. The City does not warrent the positional or themetic accurancy of the GIS data. The GIS data and cartographic digital files are not legal representations of the depicted data. Information shown on these maps is derived from public records that are constantly undergoing change. Under no circumstances shall GIS mapping be used for final design purposes. The City provides this information on an "as is" basis without warranty of any kind, express or implied. including but not limited to warranties of merchantability or fitness for a particular purpose, and assumes no responsibility for anyone's use of the information.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 23-Mar-2005
Metadata author:
City and County of San Francisco Dept of Telecommunications
c/o Jeff Johnson
Senior Application Developer
875 Stevenson St. 5th Floor
San Francisco, CA 94103
USA

415-554-5909 (voice)
415-554-0886 (FAX)
jeff.johnson@sfgov.org

Hours_of_Service: 8:00 AM - 5:00 PM
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


Generated by mp version 2.8.6 on Tue Aug 09 15:44:26 2005