Orthophoto - San Francisco - 0.25 Foot Resolution - 2001

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How should this data set be cited?

   San Francisco Dept of Public Works, 2002, Orthophoto - San Francisco - 0.25 Foot Resolution - 2001: City of San Francisco Department of Public Works, San Francisco.

   Online Links:

   • \\gisims.ci.sf.ca.us\d$\ArcIMS\Website\sfshare\catalog\test\ortho_sf_qft_2001.sid

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -122.519313

   East_Bounding_Coordinate: -122.350449

   North_Bounding_Coordinate: 37.813314

   South_Bounding_Coordinate: 37.700758

3. What does it look like?

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

   Beginning_Date: July 2001

   Ending_Date: August 2001

   Currentness_Reference: ground condition

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

   Geospatial_Data_Presentation_Form: remote-sensing image

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

      This is a Raster data set. It contains the following raster data types:

      • Dimensions 160001 x 192001 x 1, type Pixel

   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 row and column
      Abscissae (x-coordinates) are specified to the nearest 0.250000
      Ordinates (y-coordinates) are specified to the nearest 0.250000
      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.
      

7. How does the data set describe geographic features?

   Band_1

   ObjectID

   Internal feature number. (Source: ESRI)

   Sequential unique whole numbers that are automatically generated.

   Value

   Count

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • San Francisco Dept of Public Works

2. Who also contributed to the data set?

   San Francisco Dept of Public Works

3. To whom should users address questions about the data?
   Greg Braswell
   San Francisco Dept of Public Works
   

Why was the data set created?

Overlay and analysis with other spatial data

How was the data set created?

1. From what previous works were the data drawn?

   (source 1 of 1)

   Source_Contribution:

   Source Contribution: Ground Control

   Beginning date: 23-Jul-01

   Ending date: 15-Aug-01

   Source Contribution: Aerial photography

   Beginning date: 14-Aug-01

   Ending date: 28-Aug-01

   Source Contribution: Digital elevation model

   Beginning date: 10-Jun-94

   Ending date: 17-Aug-01

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

   (process 1 of 4)

   1:6600 b/w stereo aerial photography was flown in August 2001 and controlled by project ground control. The entire project was flown using a 6 inch lens and the downtown area was flown using a 12 inch lens. Additional control was recovered from an earlier (1993) overflight. Further control was derived from airborne GPS. Photo orientation was determined from a fully analytical aerotriangulation adjustment. All aerial images were scanned at 12.5 microns. All scanned images were orthorectified using the AT data and the digital elevation model. Mosaicking of the images was done using a manual stitch method.

   Person who carried out this activity:
   

   HJW GeoSpatial, Oakland CA
   8407 Edgewater Drive
   Oakland, CA 94621
   USA
   

   510-638-6122 (voice)
   

   Data sources used in this process:

   • C:\DOCUME~1\EUGENE~1\LOCALS~1\Temp\2c\xml15.tmp

   (process 2 of 4)

   Metadata imported.

   Data sources used in this process:

   • G:\ArcIMS\Website\sfshare\catalog\test\ortho_ti_qft_2001.sid.xml

   (process 3 of 4)

   Metadata imported.

   Data sources used in this process:

   • G:\ArcIMS\Website\sfshare\catalog\test\ortho_ti_1ft_2001.sid.xml

   (process 4 of 4)

   Metadata imported.

   Data sources used in this process:

   • G:\ArcIMS\Website\sfshare\catalog\test\ortho_ti_qft_2001.sid.xml

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

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

1. How well have the observations been checked?

2. How accurate are the geographic locations?

   Designed to meet +/- 2.5 feet at CE90 (NMAS for 1"=100' mapping). Tested accuracy +/- 1.0 feet at CE90.

   Testing method: 120 distributed test points were measured on stereo imagery and corresponding orthophotography. 90% of the test points on the orthophotography were within 0.72 feet of their position as measured on the stereo photography.

3. How accurate are the heights or depths?

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

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

How can someone get a copy of the data set?

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

Access_Constraints: None Known - BUT this could be in error.

Use_Constraints: None Known - BUT this could be in error.

1. Who distributes the data set?[Distributor contact information not provided.]

2. What's the catalog number I need to order this data set?

   Downloadable Data

3. What legal disclaimers am I supposed to read?

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	Size: 588.755

   • Cost to order the data:

Who wrote the metadata?

Dates:

Last modified: 04-May-2005

Metadata author:

Vince Ulfig
City of San Francisco Enterprise GIS Department
Senior GIS Engineer
875 Stevenson St
San Francisco, CA 94103
USA

(415) 554-5699 (voice)
vince.ulfig@sfgov.org

Hours_of_Service: 9 - 5 M - F

Metadata standard:

FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Metadata extensions used:

• <http://www.esri.com/metadata/esriprof80.html>