Preliminary hard and soft bottom seafloor substrate map derived from an unsupervised classification of gridded backscatter and bathymetry derivatives at Tutuila Island, American Samoa, South Pacific.

Metadata:

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

Identification_Information:

Citation:

Citation_Information:

Originator:

Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)

Publication_Date: 20080602

Title:

Preliminary hard and soft bottom seafloor substrate map derived from an unsupervised classification of gridded backscatter and bathymetry derivatives at Tutuila Island, American Samoa, South Pacific.

Geospatial_Data_Presentation_Form: digital data

Online_Linkage: http://www.soest.hawaii.edu/pibhmc/

Description:

Abstract:

Preliminary hard and soft seafloor substrate map derived from an unsupervised classification of multibeam backscatter and bathymety derivatives at Tutuila Island, American Samoa, South Pacific. The dataset was derived using a combination of Simrad em3002d and Reson 8101 backscatter, bathymetric variance and bathymetric rugosity. The sonar frequencies are 300 kHz and 240 kHz for the em3002d and the 8101 data respectively and all data were resampled to 5 m grid cell size prior to the classification. Initial supervised classifications of the backscatter data into hard and soft seafloor substrates, using seafloor photographs for groundtruthing and to define regions of interest, were used to define unsupervised class types and to visually evaluate the accuracy of the unsupervised classification seafloor substrate map.

Purpose:

The hard and soft seafloor map is being used to improve sampling techniques for long-term ecosystem monitoring, to guide future ground-truthing operations and to identify coral-rich and species specific environments. This is a preliminary product and the methods used to generate the map are currently being evaluated for their accuracy.

Supplemental_Information:

Multibeam bathymetry and backscatter data were collected aboard the R/V AHI (Acoustic Habitat Investigator) and the NOAA Ship Hiialakai. See the metadata for those datasets served separately at www.soest.hawaii.edu/pibhmc. The batymetric rugosity dataset is also served separately at the same website. The bathymetric variance grids were generated for use in the classification process and are not served separately. See the process description portion of this document for additional information about how the variance and unsupervised layers were derived.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20040225

Ending_Date: 20060226

Currentness_Reference: ground condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: As needed

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -170.928197

East_Bounding_Coordinate: -170.484814

North_Bounding_Coordinate: -14.195351

South_Bounding_Coordinate: -14.384053

Keywords:

Theme:

Theme_Keyword_Thesaurus: NCEI Geoportal Filter

Theme_Keyword: CoRIS_Metadata

Theme:

Theme_Keyword_Thesaurus: CRCP Project

Theme_Keyword:

Benthic Habitat Mapping and Characterization - American Samoa and the U.S. Pacific Remote Island Area

Theme_Keyword: 1084

Theme:

Theme_Keyword_Thesaurus: CoRIS Theme Thesaurus

Theme_Keyword:

EARTH SCIENCE > Oceans > Coastal Processes > Coral Reefs > Coral Reef Ecology > Habitats

Theme_Keyword: EARTH SCIENCE > Biosphere > Aquatic Habitat > Benthic Habitat

Theme_Keyword:

EARTH SCIENCE > Biosphere > Zoology > Corals > Reef Monitoring and Assessment > Mapping > Habitat Mapping

Theme_Keyword:

EARTH SCIENCE > Oceans > Bathymetry/Seafloor Topography > Soft Seafloor Substrate

Theme_Keyword:

EARTH SCIENCE > Oceans > Bathymetry/Seafloor Topography > Hard Seafloor Substrate

Theme:

Theme_Keyword_Thesaurus: CoRIS Discovery Thesaurus

Theme_Keyword: Geographic Information > Habitats

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category

Theme_Keyword: environment

Theme_Keyword: 007

Theme:

Theme_Keyword_Thesaurus: None

Theme_Keyword: Hard bottom

Theme_Keyword: Soft bottom

Theme_Keyword: Unsupervised Classification

Theme_Keyword: Acoustic Imagery

Theme_Keyword: Multibeam Backscatter

Theme_Keyword: Backscatter

Theme_Keyword: Bathymetry

Theme_Keyword: Multibeam sonar

Theme_Keyword: Substrate

Place:

Place_Keyword_Thesaurus: None

Place_Keyword: Tutuila Island

Place_Keyword: American Samoa

Place_Keyword: South Pacific

Place_Keyword: Pacific Ocean

Place:

Place_Keyword_Thesaurus: CoRIS Place Thesaurus

Place_Keyword:

OCEAN BASIN > Pacific Ocean > American Samoa > Tutuila Island (14S170W0016)

Place_Keyword:

COUNTRY/TERRITORY > United States of America > American Samoa > American Samoa > Tutuila Island (14S170W0016)

Place:

Place_Keyword_Thesaurus: CoRIS Region

Place_Keyword: AmSam

Access_Constraints: None

Use_Constraints:

These data are not to be used for navigation purposes. Please acknowledge the NOAA Pacific Islands Fisheries Science Center (PIFSC) Coral Reef Ecosystem Division (CRED) and the Pacific Islands Benthic Habitat Mapping Center (PIBHMC), and the Joint Institute for Marine and Atmospheric Research (JIMAR) and School of Ocean and Earth Science and Technology (SOEST), University of Hawaii as the sources of this information.

Point_of_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)

Contact_Address:

Address_Type: mailing and physical address

Address: NOAA IRC

Address: NMFS/PIFSC/CRED

Address: 1845 WASP Blvd., Building 176

City: Honolulu

State_or_Province: HI

Postal_Code: 96818

Contact_Voice_Telephone: 808 725-5360

Contact_Facsimile_Telephone: 808 725-5429

Contact_Electronic_Mail_Address: nmfs.pic.credinfo@noaa.gov

Contact_Instructions: e-mail preferred

Browse_Graphic:

Browse_Graphic_File_Name:

http://www.soest.hawaii.edu/pibhmc/amsamoa_images/TUT_unspv_hardvsoft_5m_445.jpg

Browse_Graphic_File_Description: Hard and Soft Seafloor Substrate

Browse_Graphic_File_Type: JPEG

Data_Set_Credit: PIBHMC, CRED, PIFSC, NOAA, and JIMAR

Security_Information:

Security_Classification_System: Not applicable

Security_Classification: Unclassified

Security_Handling_Description: Not applicable

Native_Data_Set_Environment:

GeoTIFF file created using ENVI 4.3 in a Microsoft Windows environment

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Data are collected for resource management and research purposes and are tested for internal consistency; however, no effort is made to compare these data to external references or to other published data.

Logical_Consistency_Report:

These data are believed to be logically consistent though no tests were performed

Completeness_Report: Complete

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Horizontal positioning system: GPS (SPS) Horizontal position accuracy: 25 meters

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

1 m Range resolution of sonar ~1.25 cm Raw sounding resolution: Variable Vertical accuracy of gridded product: 1% of water depth

Lineage:

Process_Step:

Process_Description:

Processing steps used to generate the backscatter, bathymetry, and bathymetric rugosity grids used in the unsupervised classification process are described in their own metadata that can be found at www.soest.hawaii.edu/pibhmc. Both backscatter datasets (Simrad em3002d and Reson 8101) were resampled to 5 m grid cell size using the Raster Resample Tool in the ArcMap Version 9.2 Toolbox. Resampling of the backscatter was performed after charted data in the GeoTIFF format for the individual sonar systems were mosaicked using the ArcMap Version 9.2 Toolbox Mosaic to New Raster function. Mosaics were created in the ESRI GRID format. Bathymetric variance was calculated from the 5 m bathymetry in a two-step process using ArcMap Version 9.2. The first step involved calculating the standard deviation of the bathymetry layer using the Neighborhood Statistic tool from the Spatial Analyst pull-down menu in ArcMap Version 9.2. Rectangular neighborhood settings were set to a height and width of 2 grid cells to create a small-scale variance layer. The standard deviation output was then squared using the ArcMap Raster Calculater tool. A large-scale variance layer was also generated using a rectangular neighborhood height and width of 5 grid cells. The fine-scale variance is useful for defining small features that may indicate the presence of sediment ripples or possible coral-rich areas whereas the large-scale variance is useful for defining seafloor ridges, pinnacles, and significant changes in slope. Bathymetric variance proved to be a useful tool in previous efforts to map seafloor habitats by Dartnell and Gardner (2004). Their publication can be downloaded from www.soest.hawaii.edu/pibhmc/pibhmc_documentation.htm. Two separate sets of variance and rugosity layers were then created with the same pixel dimensions as the the Reson 8101 and Simrad em3002d backscatter datasets. The datasets were handled separately because the difference in sonar frequencies between the two backscatter prevents them from being directly comparable. They should not be merged into one backscatter layer prior to classification. The layers were then opened as ESRI GRIDS in the image processing software package ENVI (Environment for Visualizing Images) Version 4.3. Two multi-band images were then created with the backscatter, small- and large-scale variance, and rugosity. A mask was also created in ENVI for each backscatter dataset. Image classification was performed separately on the two multi-band images using the K-Means unsupervised classification method, which calculates initial class means evenly distributed in the data space and then iteratively clusters the pixels into the nearest class using a minimum distance technique. More information about K-Means algorithm can be found in the ENVI documentation available at www.ittvis.com/envi/. The number of classes was set to two and all other options were set to default. Class color mapping was performed on the resulting classified images. The substrate types of hard and soft were assigned based on results from supervised classification of the backscatter data (also performed in ENVI) using hard and soft bottom classes from classified seafloor photographs. The photographs, classifications, and descriptions of the classification process are available for download at www.soest.hawaii.edu/pibhmc. The two resulting classified images, one for the Reson 8101 dataset and one for the Simrad em3002d dataset, can be mosaicked and exported as GeoTIFF files in either ArcMap or ENVI to create one image containing three classes; soft, hard bottom, and unclassified (background). In addition to the processing steps mentioned above, the high- intensity, track parallel, nadir signal was removed from the Reson 8101 backscatter data prior to classification in ENVI because it is a data acquisition artifact and causes false classification results. The nadir signal was removed by creating a 20 m buffer in ArcGIS around the R/V AHI trackline navigation data sampled every second. The buffer was used to mask the Reson 8101 backscatter data and results in the trackline parallel unclassified data gaps. Methods to most accurately interpolate across the gaps are currently under investigation.

Process_Date: 20080409

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Raster_Object_Information:

Raster_Object_Type: Grid Cell

Row_Count: 4160

Column_Count: 8181

Vertical_Count: 1

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Grid_Coordinate_System:

Grid_Coordinate_System_Name: Universal Transverse Mercator

Universal_Transverse_Mercator:

UTM_Zone_Number: -2

Transverse_Mercator:

Scale_Factor_at_Central_Meridian: 0.9996

Longitude_of_Central_Meridian: -171

Latitude_of_Projection_Origin: 0

False_Easting: 500000

False_Northing: 10000000

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: Row and Column

Coordinate_Representation:

Abscissa_Resolution: 5

Ordinate_Resolution: 5

Planar_Distance_Units: meters

Geodetic_Model:

Horizontal_Datum_Name: D_WGS_1984

Ellipsoid_Name: WGS_1984

Semi-major_Axis: 6378137.000000

Denominator_of_Flattening_Ratio: 298.257224

Vertical_Coordinate_System_Definition:

Depth_System_Definition:

Depth_Datum_Name: mean lower low water

Depth_Resolution: 0.01

Depth_Distance_Units: meters

Depth_Encoding_Method: Attribute Values

Entity_and_Attribute_Information:

Overview_Description:

Entity_and_Attribute_Overview: none

Entity_and_Attribute_Detail_Citation: none

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)

Contact_Address:

Address_Type: mailing and physical address

Address: NOAA IRC

Address: NMFS/PIFSC/CRED

Address: 1845 WASP Blvd., Building 176

City: Honolulu

State_or_Province: HI

Postal_Code: 96818

Contact_Voice_Telephone: 808 725-5360

Contact_Facsimile_Telephone: 808 725-5429

Contact_Electronic_Mail_Address: nmfs.pic.credinfo@noaa.gov

Contact_Instructions: e-mail preferred

Resource_Description: Downloadable Data

Distribution_Liability:

These data are not to be used for navigational purposes. NOAA makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: GeoTIFF, .tif

Format_Information_Content:

TIFF is a format for storage, transfer, display, and printing of raster images. The TIFF file structure allows both the tag and the image data to be encoded into the same file. GeoTIFF refers to a TIFF file that has geographic data embedded as tags within the TIFF file. The geographic data can be used to position the image in the correct location and geometry on the screen of a geographic information display. Any GIS, CAD, Image Processing, Desktop Mapping and other types of systems using geographic images can read any GeoTiff file. More specifically, files of this type can be added to ArcInfo and ArcView 8.x or higher and may be viewed in the Table of Contents as a new raster layer. Image visualization software that does not use geography as a basis for image placement can view a GeoTIFF image as if there were no geographic information in the TIFF file. For example, GeoTIFF files can be viewed using Windows Picture and Fax viewer. The GeoTIFF format is public domain, non-proprietary.

File_Decompression_Technique: none

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name:

http://www.soest.hawaii.edu/pibhmc/pibhmc_amsamoa_tutuila_geomorph.htm

Fees: None

Metadata_Reference_Information:

Metadata_Date: 20200329

Metadata_Review_Date: 20091201

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization:

Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)

Contact_Address:

Address_Type: mailing and physical address

Address: NOAA IRC

Address: NMFS/PIFSC/CRED

Address: 1845 WASP Blvd., Building 176

City: Honolulu

State_or_Province: HI

Postal_Code: 96818

Contact_Voice_Telephone: 808 725-5360

Contact_Facsimile_Telephone: 808 725-5429

Contact_Electronic_Mail_Address: nmfs.pic.credinfo@noaa.gov

Contact_Instructions: e-mail preferred

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: Universal Time

Metadata_Access_Constraints: None

Metadata_Use_Constraints: None

CoRIS:

CoRIS_ID: 20091201060548

CoRIS_Children: None

CoRIS_Beginning_Date: 20040225

CoRIS_Ending_Date: 20060226

CoRIS_Metadata_Link:

https://www.coris.noaa.gov/metadata/records/html/tut_unspv_hardvsoft_5m.html

CoRIS_Tracking_ID: 4346