TCEQ One Meter Digital Orthophoto Quarter Quads

Documentation describing TCEQ One Meter Digital Orthophoto Quarter Quads (spatial data layer).

This is a portion of DOQQ 2896491 (Saint Charles Bay NW), showing the Cavasso Creek Bridge. The Aransas National Wildlife Refuge lies to the east of the creek.

Additional DOQ Samples for Browsing!

1 - Identification Information
2 - Data Quality Information
3 - Spatial Data Organization Information
4 - Spatial Reference Information
5 - Entity and Attribute Information
6 - Distribution Information
7 - Metadata Reference Information

The following text conforms with the hierarchy of data elements in the FGDC Content Standards for Digital Geospatial Metadata.

1 IDENTIFICATION_INFORMATION:

1.1 Citation:

8.1 Originator: Texas Commission on Environmental Quality

(TCEQ)

8.2 Publication_Date: 20010723
8.4 Title: TCEQ 3.75 Minute Digital Orthoimagery
8.6 Geospatial_Data_Presentation_Form: remote-sensing image
8.8 Publication_Information:

8.8.1 Publication_Place: Austin, TX
8.8.2 Publisher: TCEQ

1.2 Description:

1.2.1 Abstract:

A DOQ is a digital image of a high-altitude aerial photograph in which the displacements caused by the camera angle and surface variations of the photographed terrain have been removed. This gives a DOQ the same geometric properties as a paper map; it is thus possible to use a DOQ for the direct measurement of distances, areas, angles, and positions. A standard DOQ image covers 3.75 minutes of latitude by 3.75 minutes of longitude (one-quarter of a USGS 7.5 minute quadrangle); it has a ground resolution (the area of the ground represented in each pixel in x and y components) of one meter.

TCEQ has acquired these DOQs in a cost share arrangement with the USGS and in cooperation with the Texas Orthoimagery Program (TOP). These DOQs will eventually be distributed along with the TOP DOQs by the Texas Natural Resources Information System.

Listings of TCEQ DOQQ EISYS numbers and names can be obtained by going to the TCEQ USGS Topographic Map Viewer

Step By Step Instructions:
1) click the link to TCEQ USGS Topographic Map Viewer
2) click "Go to the Map Viewer"
3) click left mouse button and hold down to draw a box
4) continue drawing boxes to Zoom in to the area of interest until DOQQ Index appears in the Legend (on the right side of the screen)
5) click the radio button next to the DOQQ entry in the Legend
6) click the identify tool in the tool box (on the left side of the screen)
7) click inside any of the DOQQ squares
8) read and note the DOQQ information (at the bottom of the screen)

1.2.2 Purpose:

A DOQ-derived base map of the State of Texas will provide a common framework for mapping standards and development across state agencies. A standardized base map will not only promote consistency in data collection and reporting procedures across Texas state agencies, but will also make possible easier access to data maintained by different agencies. The richness of the information content provided by DOQs improves the quality of the information used by decision makers, thus improving the basis for management decisions. Because DOQs are raster-based, it is possible to use them for on-screen digitizing of vector layers. Because National Aerial Photography Program (NAPP) photography is made every five years, obtaining DOQs for a geographic area make it possible to chart changes in land use and characteristics over time and thus makes temporal analysis possible. The detail of information provided by DOQs makes it possible to use them for locating fixed sites (such as water monitoring sites and water diversion points), which is less costly and time consuming than having field crews locate the points using Global Positioning System (GPS) receivers.

1.2.3 Supplemental_Information:

Supplemental information about DOQs can be obtained at the following locations. Standards for Digital Orthophotos 12/96 can be found at: http://rmmcweb.cr.usgs.gov/public/nmpstds/acrodocs/doq/PDOQ1296.PDF

(This document requires an Acrobat reader.)

Background information on DOQs, including file structure and processing steps, can be found at: http://edcwww.cr.usgs.gov/glis/hyper/guide/usgs_doq

.

A detailed description of USGS DOQ processing and creation can be viewed at: http://mapping.usgs.gov/digitalbackyard/faqsnew.html

The USGS DOQ Metadata file can be viewed at: http://edcsns17.cr.usgs.gov/EarthExplorer/

.

The file names follow the EISYS quarter quad numbering convention for 3.75-5 minute DOQs. In this convention:

Characters 1-2 represent the latitude in degrees North of the one-degree area containing the DOQ.

Characters 3-4 represent the longitude in degrees West of the one-degree area containing the DOQ.

Characters 5-6 are a two-digit number ranging from 01 to 64 that specifies the position of the USGS 7.5-minute quad that contains the DOQ. Quads are counted from west to east, starting with the north-most row.

Character 7 signifies the quarter-quad: NW=1, NE=2, SW=3, SE=4.

Character 8 is always capital "A". This signifies that the DOQ has a one meter ground resolution and is represented using 24 bits per pixel.

For example, the southeast DOQ of the Pflugerville West 7.5-minute quad would have an EISYS number of 3097354A, as represented in the TCEQ DOQQ Numbering Convention Demonstration.

1.3 Time_Period_of_Content:

9.3 Range_of_Dates/Times:

9.3.1 Beginning_Date: Unknown
9.3.3 Ending_Date: Unknown

1.3.1 Currentness_Reference: The DOQQs were derived from NAPP photography

that was taken during 1995 and 1996. Exact dates for all
photography vary with each individual DOQQ.

1.4 Status:

1.4.1 Progress: Complete.

1.4.2 Maintenance_and_Update_Frequency:

As needed.

1.5 Spatial_Domain:

1.5.1 Bounding_Coordinates:

1.5.1.1 West_Bounding_Coordinate: -98.5
1.5.1.2 East_Bounding_Coordinate: -93.0
1.5.1.3 North_Bounding_Coordinate: 30.0
1.5.1.4 South_Bounding_Coordinate: 26.0

1.6 Keywords:

1.6.1 Theme:

1.6.1.1 Theme_Keyword_Thesaurus: None
1.6.1.2 Theme_Keyword: digital orthophoto quad
1.6.1.2 Theme_Keyword: 1-Meter DOQ
1.6.1.2 Theme_Keyword: DOQ
1.6.1.2 Theme_Keyword: DOQQ
1.6.1.2 Theme_Keyword: digital orthophoto
1.6.1.2 Theme_Keyword: digital orthoimage
1.6.1.2 Theme_Keyword: digital orthoimagery
1.6.1.2 Theme_Keyword: digital orthophoto quarter quad
1.6.1.2 Theme_Keyword: geo-referenced raster image

1.6.2 Place:

1.6.2.1 Place_Keyword_Thesaurus: None
1.6.2.2 Place_Keyword: Texas

1.7 Access_Constraints: None

1.8 Use_Constraints: Please credit the Texas Commission on

Environmental Quality when using a DOQQ obtained from TCEQ in a published hardcopy or digital product.

1.9 Point_of_Contact:

10.1 Contact_Person_Primary:

10.1.1 Contact_Person: Greg Smithhart
10.1.2 Contact_Organization: TCEQ

10.4 Contact_Address:

10.4.1 Address_Type: Mailing address
10.4.2 Address: P.O. Box 13087 (Mail Code 197)
10.4.3 City: Austin
10.4.4 State_or_Province: TX
10.4.5 Postal_Code: 78711-3087
10.4.6 Country: USA

10.5 Contact_Voice_Telephone: 512-239-0859

10.7 Contact_Facsimile_Telephone: 512-239-0888

10.8 Contact_Electronic_Mail_Address:

gsmithha@tceq.texas.gov

1.10 Browse_Graphic: