Wayne County Orthophotography

Metadata also available as

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: Wayne County Geographic Management Unit

Publication_Date: 5/18/1998

Publication_Time: Unknown

Title: Wayne County Orthophotography

Edition: 1.0

Geospatial_Data_Presentation_Form: map

Publication_Information:

Publication_Place: Detroit, MI

Publisher: Wayne County Geographic Management Unit

Description:

Abstract:

The County encompasses an area of approximately 622 square miles. The project terrain varies from low-lying, level ground to rolling hills. Development density ranges from suburban to highly urbanized, most notably in and around Detroit. The County, including all of Detroit, was flown at a negative scale of 1" = 660' with a mapping scale of 1"=100'. Flight lines were not centered on the PLSS sections. This photography shall be utilized for all 1" = 100' products. A small section of downtown Detroit was captured at 1" = 1,000' with a high degree of overlap and sidelap. This area also required the use of an aerial camera having a calibrated focal length of about 304mm (12"). All exposures for this photography have been aerotriangulated. Airborne GPS control and supplemental GPS ground control were used. One set of black and white contact prints was produced, and one set of diapositives was prepared. These products were used for control marking The aerial camera used was a precision aerial mapping camera equipped with a low distortion, high resolution lens. The camera was also equipped to record a signal triggered by a camera exposure on a GPS time scale. The epoch rate of the GPS receivers matched that of the camera exposures. This condition enables precise interpolation of the camera's position at the instant of photo exposure. The had a maximum aperture of f/4, or f/4.5, and met the requirements based on a U.S. Geological Survey Report of Calibration. Aerial photography was taken in the spring of 1997, 1999, 2000 and 2001 not to exceed April 30th. The flight was a leaf off flight when deciduous trees are barren. The flight occured within two hours before and two hours after maximum sun angle when the sun angel is not less than 30 degrees. The photography was taken when no snow, haze, fog or dust were present on the ground and when streams were within their normal banks; or when cloud shadows represent no more than five percent (5%) of the area in any one photograph. The photography flight was flown during the first acceptable day(s) available, and as close together as possible, weather permitting, preferably on consecutive days.

Purpose:

To have a visual georeferenced image to create and quality control other geographic datasets.

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 19980518

Time_of_Day: Unknown

Currentness_Reference: publication date

Status:

Progress: Complete

Maintenance_and_Update_Frequency: Irregular

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: 0

East_Bounding_Coordinate: 0

North_Bounding_Coordinate: 0

South_Bounding_Coordinate: 0

Keywords:

Theme:

Theme_Keyword_Thesaurus: Dataset Types

Theme_Keyword: Ortho Photography

Theme_Keyword: Imagery

Place:

Place_Keyword_Thesaurus: Geographic Places

Place_Keyword: United States

Place_Keyword: Michigan

Place_Keyword: SE Michigan

Place_Keyword: Wayne County

Place_Keyword: City of Livonia

Access_Constraints:

A request must be sent to the Wayne County Geographic Information Systems Management Unit.

Use_Constraints:

Neither the County nor its employees makes any warranty, express or implied, including the warranties of merchantability and fitness for a particular purpose, or assumes any legal liability or responsibility for the accuracy, functioning, completeness, or usefulness of the County basemap or other County GIS themes.

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Steve Perry

Contact_Organization: Wayne County Geographic Information Systems Management Unit

Contact_Position: Technical Manager

Contact_Address:

Address_Type: mailing and physical address

Address: 415 Clifford

City: Detroit

State_or_Province: MI

Postal_Code: 48226

Country: USA

Contact_Voice_Telephone: 313-224-6334

Contact_Facsimile_Telephone: 313-224-0857

Contact_Electronic_Mail_Address:

Hours_of_Service: 8:00am - 5:00pm

Contact_Instructions: Email or Voicemail

Browse_Graphic:

Data_Set_Credit: Analytical Services Inc. and Wayne County

Native_Data_Set_Environment: Tagged Information File Format (TIFF)

Data_Quality_Information:

Logical_Consistency_Report:

ASI developed a new and highly sophisticated production software tool for creating digital orthophoto imagery called METRO (Method for the Elimination of Tilt and Relief Displacement in Orthophotography). The METRO system uses derived DTM's to fully rectify aerial images for accurate survey control. It offers several advantages over commercially available DOI software such as:

The METRO process can handle aerial photography acquired at any angle, not only N-S or E-W.

Fiducials on the scanned images are calculated with an automated feature-recognition program, which eliminates human error and produces more accurate results than manual processes.

Every negative is scanned as a seperate orthophoto. This minimizes displacement problems that arise from using imagery at the edge of the photograph and results in a more accurate product.

Edge enhancement is performed on every image during the scanning process to improve interpretability.

A sophisticated color balancing technique was developed to match adjacent imagery. This color balancing utilizes spatial-domain image processing as well as spatial-filtering algorithms.

A unique mosaicking process performs pixel matching along the seam line. This process virtually eliminates image distortions caused by above ground features mosaicked from two adjacent photographs.

TIN's are used for rectification, not regular grid DEM's. The TIN provides for a more accurate representation of the terrain surface for generating better digital orthophotos. This means that errors, due to interpolation on a regular grid, are minimized. The TIN eliminates ""waviness"" around sharp terrain breaks.

True orthophoto-modeling is used to correct bridge distortions in the photography.

Completeness_Report: Dataset is complete.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

One of the following horizontal accuracy requirement industry standards was followed.

1. United States National Map Accuracy Standards, Office of Management and Budget (OMB).

2. American Society of Photogrammetry and Remote Sensing (ASPRS) Accuracy Standards for Large Scale Maps.

3. American Society of Photogrammetry (ASP) Specifications for Aerial Surveys and Mapping by Photogrammetry Methods for Highways.

4. U.S. Department of Transportation (DOT) Surveying and Mapping Manual Map Standards.

5. U.S. Army Corp of Engineers (USACE), Enginerring and Design, photogrammetric Mapping.

6. U.S. National Cartographic Standards for Spatial Accuracy.

The GPS points that were collected to provide additional control for high accuracy analytical aero-triangulation solutions from existing aerial photography. The internal accuracy of the network achieved first order class 1 standards in all station pairings, i.e., the relative horizontal position accuracy between stations in the network does not exceed 10 mm + 10 ppm of the station separation. The GPS network met the current Federal Geodetic Control Subcommittee (FGCS) accuracy standards. The GPS network, based on existing National Geodetic Reference System (NGRS) control, consists of 21 stations of which one is an existing HARN B-order horizontal control point, one is an existing HARN B-order horizontal/first order vertical control point, and one is an existing HARN A-order horizontal/second order vertical control point upon which the network is based.

Lineage:

Source_Information:

Source_Citation:

Citation_Information:

Publication_Date: June 1999

Title: Wayne County Photgrametric and GPS Control Suurvey Reports

Source_Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Time_of_Day: Unknown

Process_Step:

Process_Description:

Seven catagories of image quality have been selected for evaluation based upon aesthetic and spatial importance.

1) Mosaicking - The process by which two adjacent images are seamed together using a linear algorithm. This includes a smoothing function that will attempt to minimize the sharp radiometric difference that may occur between images. An image that has a ""checkerboard"" look to it may be mosaicked, but not radiometrically corrected.

Ratings

1 = One or more images have very sharp contrast on all sides.

2 = Significant visible difference of seams between flightlines.

3 = Visible difference of seams between flightlines.

4 = One seam on one image not corrected.

5 = No radiometric seams between images.

Process_Date: Unknown

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Steve Perry

Contact_Organization: Wayne County Geographic Information Systems Management Unit

Contact_Position: Technical Manager

Contact_Address:

Address_Type: mailing and physical address

Address: 415 Clifford

City: Detroit

State_or_Province: MI

Postal_Code: 48226

Country: USA

Contact_Voice_Telephone: 313-224-6334

Contact_Facsimile_Telephone: 313-224-0857

Contact_Electronic_Mail_Address:

Hours_of_Service: 8:00am - 5:00pm

Contact_Instructions: Email or Voicemail

Process_Step:

Process_Description:

Seven catagories of image quality have been selected for evaluation based upon aesthetic and spatial importance.

2) Edgematching - When mosaicking images together, it is possible that each image may not precisely join or geometrically edgematch to an adjacent image. Visual inspection of the imagery should be performed to ensure that features on the ground along the edge of each image line up exactly with the same features on the edge of the adjacent image.

Ratings for .5 foot resolution imagery

1 = Edgematching of images is off > 5 pixels.

2 = Edgematching of images is off 5 pixels.

3 = Edgematching of images is off 3-4 pixels.

4 = Edgematching of images is off 1-2 pixels.

5 = Images are edgematched precisely.

Process_Date: Unknown

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Steve Perry

Contact_Organization: Wayne County Geographic Information Systems Management Unit

Contact_Position: Technical Manager

Contact_Address:

Address_Type: mailing and physical address

Address: 415 Clifford

City: Detroit

State_or_Province: MI

Postal_Code: 48226

Country: USA

Contact_Voice_Telephone: 313-224-6334

Contact_Facsimile_Telephone: 313-224-0857

Contact_Electronic_Mail_Address:

Hours_of_Service: 8:00am - 5:00pm

Contact_Instructions: Email or Voicemail

Process_Step:

Process_Description:

Seven catagories of image quality have been selected for evaluation based upon aesthetic and spatial importance.

3) Foreign Artifacts - Throughout the digital orthophoto production process there exists the unfortunate problem of partical matter coming in contact with the original film or diapositive. This particulate matter can be introduced into the digital file at the time of scanning. The effect will be more noticeable in the scanning of small scale aerial photography because of the magnification involved. The critical factor in this evaluation is whether important data is obscured.

Ratings

1 = >25 particles and/or critical information is obscured.

2 = >20 and <25 artifacts.

3 = >10 and <20 artifacts.

4 = >0 and <10 artifacts.

5 = zero artifacts.

Process_Date: Unknown

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Steve Perry

Contact_Organization: Wayne County Geographic Information Systems Management Unit

Contact_Position: Technical Manager

Contact_Address:

Address_Type: mailing and physical address

Address: 415 Clifford

City: Detroit

State_or_Province: MI

Postal_Code: 48226

Country: USA

Contact_Voice_Telephone: 313-224-6334

Contact_Facsimile_Telephone: 313-224-0857

Contact_Electronic_Mail_Address:

Hours_of_Service: 8:00am - 5:00pm

Contact_Instructions: Email or Voicemail

Process_Step:

Process_Description:

Seven catagories of image quality have been selected for evaluation based upon aesthetic and spatial importance.

4) Scratches - These conditions can be developed while the film is still in the aerial camera, during film processing or diapositive creation. Scratches are more prevalent in small scale photography as higher scanning magnification is typically required.

Ratings

1 = >15 scratches and/or critical information is obscured.

2 = >15 scratches.

3 = >10 and <15 scratches.

4 = >0 and <10 scratches.

5 = zero scratches.

Process_Date: Unknown

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Steve Perry

Contact_Organization: Wayne County Geographic Information Systems Management Unit

Contact_Position: Technical Manager

Contact_Address:

Address_Type: mailing and physical address

Address: 415 Clifford

City: Detroit

State_or_Province: MI

Postal_Code: 48226

Country: USA

Contact_Voice_Telephone: 313-224-6334

Contact_Facsimile_Telephone: 313-224-0857

Contact_Electronic_Mail_Address:

Hours_of_Service: 8:00am - 5:00pm

Contact_Instructions: Email or Voicemail

Process_Step:

Process_Description:

Seven catagories of image quality have been selected for evaluation based upon aesthetic and spatial importance.

5) Brightness - The natural reflectance of many materials on the ground can sometimes cause problems with digital orthophoto imagery. These include washed out areas, little or no detail in affected area, and radiometric/mosaicking problems. The clarity of ground features in these so-called bright areas is the critical factor to evaluate.

Ratings

1 = zero contrast in bright areas and/or critical information is obscured.

2 = <10 pixel values in bright areas.

3 = >65% of ground features are interpretable in bright areas.

4 = >75% of ground features are interpretable in bright areas.

5 = >90% of ground features are interpretable in bright areas.

Process_Date: Unknown

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Steve Perry

Contact_Organization: Wayne County Geographic Information Systems Management Unit

Contact_Position: Technical Manager

Contact_Address:

Address_Type: mailing and physical address

Address: 415 Clifford

City: Detroit

State_or_Province: MI

Postal_Code: 48226

Country: USA

Contact_Voice_Telephone: 313-224-6334

Contact_Facsimile_Telephone: 313-224-0857

Contact_Electronic_Mail_Address:

Hours_of_Service: 8:00am - 5:00pm

Contact_Instructions: Email or Voicemail

Process_Step:

Process_Description:

Seven catagories of image quality have been selected for evaluation based upon aesthetic and spatial importance.

6) Shadows - These natural occurrences can cause interpretability problems in digital orthophoto imagery. It is always desirable to capture as much detail as possible in shadow areas. Establishing criteria for acceptable density ranges in the aerial negatives at project startup will ensure that detail will exist to be captured. Shadow detail may also be inconsistent due to differences in the time and date of the aerial photography.

Ratings

1 = zero contrast in shadow area and/or critical information is hidden in shadow.

2 = <10 pixel valuesin shadow areas.

3 = >65% of ground features are interpretable in shadow areas.

4 = >75% of ground features are interpretable in shadow areas.

5 = >90% of ground features are interpretable in shadow areas.

Process_Date: Unknown

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Steve Perry

Contact_Organization: Wayne County Geographic Information Systems Management Unit

Contact_Position: Technical Manager

Contact_Address:

Address_Type: mailing and physical address

Address: 415 Clifford

City: Detroit

State_or_Province: MI

Postal_Code: 48226

Country: USA

Contact_Voice_Telephone: 313-224-6334

Contact_Facsimile_Telephone: 313-224-0857

Contact_Electronic_Mail_Address:

Hours_of_Service: 8:00am - 5:00pm

Contact_Instructions: Email or Voicemail

Process_Step:

Process_Description:

Seven catagories of image quality have been selected for evaluation based upon aesthetic and spatial importance.

7) Contrast - The range contrast between the darkest and brightest areas within a photo is a critical factor affecting image clarity and interpretability. A histogram of the levels of gray or brightness within an image can provide a measure of image contrast and ascertain characteristics of the image such as whether pixel compression exists or stretching algorithms have been applied.

Ratings

1 = <60% of gray scale used and/or critical information is obscured.

2 = >60% and <70% of gray scale used.

3 = >70% and <80% of gray scale used.

4 = >80% and <90% of gray scale used.

5 = >90% of gray scale used.

Process_Date: Unknown

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Steve Perry

Contact_Organization: Wayne County Geographic Information Systems Management Unit

Contact_Position: Technical Manager

Contact_Address:

Address_Type: mailing and physical address

Address: 415 Clifford

City: Detroit

State_or_Province: MI

Postal_Code: 48226

Country: USA

Contact_Voice_Telephone: 313-224-6334

Contact_Facsimile_Telephone: 313-224-0857

Contact_Electronic_Mail_Address:

Hours_of_Service: 8:00am - 5:00pm

Contact_Instructions: Email or Voicemail

Cloud_Cover: 5

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Raster_Object_Information:

Raster_Object_Type: Pixel

Row_Count: 4800

Column_Count: 7200

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Grid_Coordinate_System:

Grid_Coordinate_System_Name: State Plane Coordinate System

State_Plane_Coordinate_System:

SPCS_Zone_Identifier: 2113

Lambert_Conformal_Conic:

Standard_Parallel: 42.1

Standard_Parallel: 43.6666666667

Longitude_of_Central_Meridian: -84.3333333334

Latitude_of_Projection_Origin: 41.5

False_Easting: 4000000

False_Northing: 0

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: row and column

Coordinate_Representation:

Abscissa_Resolution: 0

Ordinate_Resolution: 0

Planar_Distance_Units: international feet

Geodetic_Model:

Horizontal_Datum_Name: North American Datum of 1983/96

Ellipsoid_Name: Clarke 1866

Semi-major_Axis: 6378206

Denominator_of_Flattening_Ratio: 294.9786982

Vertical_Coordinate_System_Definition:

Altitude_System_Definition:

Altitude_Datum_Name: North American Vertical Datum of 1988

Altitude_Distance_Units: feet

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: Captured

Overview_Description:

Entity_and_Attribute_Overview:

For panchromatic source each pixel contains an 8-bit gray-scale value between 0-255. A value of 0 represents black while a value of 255 represents white. Values between 0 and 255 are repesented as a shade of gray.

Distribution_Information:

Distribution_Liability:

Neither the County nor its employees makes any warranty, express or implied, including the warranties of merchantability and fitness for a particular purpose, or assumes any legal liability or responsibility for the accuracy, functioning, completeness, or usefulness of the County basemap or other County GIS themes.

Standard_Order_Process:

Fees: $120.00 per sq mi

Available_Time_Period:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 19990804

Time_of_Day: Unknown

Metadata_Reference_Information:

Metadata_Date: 20010808

Metadata_Review_Date: 20010115

Metadata_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Steve Perry

Contact_Organization: Wayne County Geographic Information Systems Management Unit

Contact_Position: Technical Manager

Contact_Address:

Address_Type: mailing and physical address

Address: 415 Clifford

City: Detroit

State_or_Province: MI

Postal_Code: 48226

Country: USA

Contact_Voice_Telephone: 313-224-6334

Contact_Facsimile_Telephone: 313-224-0857

Contact_Electronic_Mail_Address:

Hours_of_Service: 8:00am - 5:00pm

Contact_Instructions: Email or Voicemail

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time

Metadata_Security_Information:

Metadata_Security_Classification_System: None

Metadata_Security_Classification: Unclassified

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