In 2006 and 2007 the NOAA Coastal Services Center purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic habitat data from this imagery for selected Texas coastal bend bays. The Center worked cooperatively with the Texas Parks and Wildlife Department (TPWD) and the Texas A&M University Center for Coastal Studies to develop benthic habitat data, primarily Submerged Aquatic Vegetation (SAV) for several coastal bays. This data will support the state's recently adopted Seagrass Monitoring Program which calls for regional mapping of SAV for status and trends assessment. The Center, Texas A&M, and TPWD have coordinated on the requirements of this project.
These data have been created as a result of the need for having geospatial data immediately available and easily accessible in order to enhance the capability of the NOAA Coastal Services Center (CSC)
Benthic habitat vector data for lower laguna madre was divided into three study areas. The geographic extent of these areas is ~800mi2. Benthic habitat data was generated from 2004 NAIP imagery for all estuarine lands below mean high water within the study area. No benthic data was required for the marine side of the barrier beaches.
Publication Date
None
7320 Executive Way
NOAA Coastal Services Center
Horizontal accuracy of the reprocessed source imagery was verified to be better than 5 meters at 90% confidence level in accordance with National Map Accuracy Standards for a 1-meter GSD. The accuracy of the contractor's final map is 89% and the accuracy of the final map is 90%. Overall final map deterministic accuracy is 88% (with fuzzy accuracy at 90%) which exceeds the contract standard of 85%. Additionally, 14 of the 16 final map class producer's and consumer's accuracies are at 85% which exceeds the contract standard of 80%. However, the deterministic producer's accuracy for emergent marsh is 77%, and the user's accuracy for unconsolidated sediments is 72%.
For the reprocessed imagery, compliance with the accuracy standard was ensured by the placement of photo identifiable ground control points. A total of 18 photo identifiable ground survey points was used for the calculations. An RMS value was calculated based on the imagery reprocessed for this project by comparing the aerotriangulated X and Y coordinates. This value represents an estimate of the accuracy of the horizontal coordinate measurements in the tile expressed in meters. For the final map product Initial Map accuracy assessment was used as a tool to prioritize areas for further field examination and after field investigation to prioritize those areas where additional modeling or interpretation was needed. Error matrices showing both deterministic and fuzzy accuracies were compiled for the initial map. Based on the results compiled from the assessment, the team visit any classes exhibiting inaccuracy and addressed the classes through modeling, additional analysis or manual editing.
Compliance with the accuracy standard for the reprocessed imagery was ensured by the placement of photo identifiable ground control points and the collection of airborne GPS data. Compliance with the accuracy standard for the final map product was ensured by field checks and manual editing.
Accuracy assessment determined by evaluating the horizontal accuracy obtained during the aerotriangulation process for each lift for the reprocessed imagery and by field verification for the completed map product.
TerraSurv, Inc. of Pittsburgh, PA was contracted by EarthData International of Frederick, MD to perform a geodetic control survey in support of mapping an area along the southeasterly coast of Texas between Port Lavaca and Brownsville. Thirty-eight photo identifiable locations were surveyed to provide ground control and quality assurance checks for the mapping. Twenty of the stations were used for mapping control and eighteen of the stations were used for quality checks. The horizontal datum was the North American Datum of 1983, CORS adjustment (NAD 1983 CORS). The vertical datum was the North American Vertical Datum of 1988 (NAVD 1988).
The digital orthophotography was developed from imagery acquired as part of the 2004 overflight of the State of Texas developed for the USDA National Agricultural Imagery Program (NAIP). In order to achieve a horizontal accuracy of 5 meters, CE90 it is necessary to reprocess the imagery incorporating new GPS field control. It should be noted that the imagery was not tide coordinated so tidal variation may exist between sorties. The imagery was acquired between November 3, 2004 and November 7, 2004.
The original 1m DOQQs for the project area were resampled to 2m and mosaicked. For habitat classification, the mosaicked imagery was divided into two processing areas; one set of two mosaics for true color and one set of two mosaics for color-IR. Image segmentation was performed using on the blue, green, red, and near-infrared bands for each of the six processing areas. The classification of the habitat segments (as ESRI polygon shapefiles) was performed using CART analysis. The habitat maps for each of the two areas was refined with the aid of field data collected during July, August, and October 2007. The two processing area shapefiles were edgematched and combined into a single shapefile which was clipped to the final project area boundary and then clipped into three separate shapefiles; north, middle, and south regions. Adjacent regions do not overlap. Each polygon, within and across all three delivery regions, has a unique polygon identification number. Each shapefile was checked for proper topology and to insure that each polygon has a correct habitat label, habitat code, modifier label if resent, unique identification number, and an area calculation. Polygons below the 100m2 minimum mapping unit (MMU) were eliminated, though some polygons <100m2 were retained if their area changed to below the MMU due to the polygon boundary smoothing process. The habitat data also went through an independent validation review. Accuracy assessment was performed on seven classes with Patchy SRV and Continuous SRV being combined into a single accuracy class. For field data collection, non-random sites in the form of polygons were chosen by analysts with an attempt to sample all available image signatures. These sites were visited in the field and data on each site was collected directly into digital format (ESRI shapefile) using a laptop or onto a paper form that was later entered into digital format. Sites were navigated to primarily using a Garmin GPS 76 unit connected to a Panasonic Toughbook laptop displaying the project imagery and polygons in ArcMap v9.1 or using the GPS unit alone. Habitat classification was estimated as accurately as possible using methods or combination of methods which included above water observation, snorkeling, wading, and underwater video. This data was entered into an ESRI shapefile via a digital field form in ArcMap specifically developed for this type of field data collection. More sample polygon sites were collected in-office based on the in-field collected sites in order to meet the 30 sites per class accuracy assessment requirement. For each class, a random selector macro in ArcMap was used to randomly select 30 sites for accuracy assessment. The entire pool of accuracy sites was kept separate from the remaining sites and only used for accuracy assessment during the project. Anonymity of the accuracy sites was maintained throughout the project because it was unnecessary to ever visually review these sites in order to perform the accuracy analysis. More accuracy assessment sites were collected in a later field collection to add to the analysis. These sites were chosen by randomly selecting polygons within specific regions that were pre-determined to be visited. Information for these sites was collected using the same methods for the other sites. Accuracy information was compiled using ArcMap. The zonal stats tool in ArcMap was used to determine the majority map class each accuracy polygon intersected with. An accuracy assessment error matrix was generated using this information by importing it to Microsoft Excel and building the matrix. Both deterministic and fuzzy accuracy assessment were performed. The accuracy analysis and error matrices are presented and discussed in the Lower Laguna Madre Final Accuracy Assessment Report.
Not applicable
2234 South Hobson Avenue
Users must assume responsibility to determine the usability of these data.
2234 S Hobson Ave.
