This dataset represents the complete elevation information for the area of interest in GeoTIFF format.
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
This GeoTIFF is a combination of two dataset that provide the best-available data for the land elevations and the bathymetry of Chesapeake Bay. The 7.5-minute elevation data for the conterminous United States are the primary initial source data for the land elevation and were acquired from the National Elevation Dataset (NED). The bathymetry dataset was acquired from the NOAA estuarine bathymetry website. This dataset was derived from two hundred ninety-seven surveys dating from 1850 to 1993. The NED website does not specify any value for horizontal accuracy. According to the metadata accompanying the bathymetry dataset, the horizontal accuracy is expressed as an estimated root mean square error (RMSE). The estimate of the RMSE is based upon horizontal accuracy tests of the source soundings used to generate the DEM. As a first approximation the locational accuracy of the source soundings are 0.0015 m at source "Smooth Sheet" scale (120 m @ 1:80,000 to 15 m @ 1:10,000). Smooth Sheets are maps generated as a principle product of each (historic) hydrographic survey with fully corrected soundings plotted on them. In both cases the user needs to refer to the original datasets to establish the details of the data and their estimates of accuracy.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
The metadata accompanying the NED dataset does not specify a vertical accuracy. However, the website indicates the vertical accuracy of the National Elevation Dataset (NED) varies spatially because of the variable quality of the source digital elevation models (DEMs). As such, the NED inherits the accuracy of the source DEMs. The most recently published figure of overall absolute vertical accuracy expressed as the root mean square error (RMSE) is 2.44 meters. The estuarine bathymetry metadata indicates the vertical RMSE statistic is used to describe the vertical accuracy of a DEM. It encompasses both random and systematic errors introduced during production of the data. The RMSE is encoded in element number 5 of record C of the DEM. This accuracy estimate includes components related to quantization of the source soundings (1.3 to 0.15 m), the systematic editing of the source data (1percent or 0.10m), un-sampled bathymetric features (estimated at less than 5 percent of depth), time related changes (erosion, deposition, and seismic shifts), and dredging operations (cut and fill). It is estimated that the accuracy of the Bathymetric DEMs is 2 percent of depth or 1 meter for depths grater than 20 meters and 2 percent of depth or 0.20 meters for depths shallower than 20 meters. THESE DEMs SHOULD NOT BE USED FOR NAVIGATION. The two datasets used to create this merged product are referenced to different vertical datums. The NED data use a vertical datum of NAVD88 while the estuarine data simply specifies the vertical datum as referenced to the local tidal datum at the time of the hydrographic survey. No adjustment was made to the individual datasets to attempt to eliminate this discrepancy. The user needs to refer to the original datasets to establish the details of the data and their estimates of accuracy.
Process_Step:
Process_Description:
Within ArcMap 9.2 a special legend was created for the poto_area elevation grid. The grid intervals were set using VACExtras version 2.1 - Raster - Legend Classifier. (VACExtras is an extension written and maintained in Woods Hole, MA for a collection of tools useful in ArcGIS). Once the legend intervals were established, colors at critical intervals were chosen and then these colors were ramped over the entire grid within the symbology window of the dataset.
Source_Used_Citation_Abbreviation: poto_area
Process_Date: 2009
Source_Produced_Citation_Abbreviation: poto_area
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
VACExtras 2.1 (within ArcMap 9.2) was then used to export this specialized color map to a text file in Fledermaus RGB format (Raster - Export Fledermaus Color Legend).
Source_Used_Citation_Abbreviation: poto_area
Process_Date: 2009
Source_Produced_Citation_Abbreviation: arcgiscolor.txt
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
An AWK script was written to reformat this text file into a format compatible with a GMT RGB ASCII color map.
Source_Used_Citation_Abbreviation: arcgiscolor.txt
Process_Date: 2009
Source_Produced_Citation_Abbreviation: tst.cpt
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
The combined elevation grid (poto_area:
http://pubs.usgs.gov/of/2009/1151/data/basemap/elevation/poto_area.zip) was loaded into Mirone, version 1.5.0. Mirone is a MATLAB-based framework tool that allows the display and manipulation of a large number of grid format. This particular version is a stand-alone version intended to run under Windows (not requiring MATLAB). Mirone is capable of reading an ArcGIS binary grid. With the grid loaded, the newly generated ASCII color map was also loaded (Image - Color Palettes - Change Palette - File - Read GMT Palette - As Master).
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
Using Mirone - Image - Illuminate - GMT grdgradient - option 1 (which is the GMT grdgradient classic), setting the Azimuth to 315 - the falsely colored grid is converted to a color-hillshade. This display was then exported as a GeoTIFF image using File - Save Image As - GeoTIFF. The option to "Preserve Image original size" was selected.
Source_Used_Citation_Abbreviation: poto_area
Source_Used_Citation_Abbreviation: tst.cpt
Process_Date: 2009
Source_Produced_Citation_Abbreviation: clrhshd_poto.tif
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
GeoTIFFExamine was then used to open the GeoTIFF to verify the header information and to write a TIFF world file including this information.
Source_Used_Citation_Abbreviation: clrhshd_poto.tif
Process_Date: 2009
Source_Produced_Citation_Abbreviation: clrhshd_poto.tfw
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: Woods Hole Coastal and Marine Science Center
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: (508) 548-8700 x2251
Contact_Facsimile_Telephone: (508) 457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
The UTM, Zone 18, NAD83 color-hillshade relief TIFF image was projected to Geographic, NAD83. This was accomplished in ArcCatalog (v. 9.2) using ArcToolbox - Data Management Tools - Projections and Transformations - Raster - Project Raster. The parameters were as follows: Input raster: clrhshd_poto.tif; input coordinate system automatically supplied as NAD_1983_UTM_Zone_18N; output raster: clrhshd_poto_geo.tif; output coordinate system: GCS_North_American_1983; no geographic transformation; resampling technique: bilinear; output cell size left to default (0.00027); no registrations points supplied.
Source_Used_Citation_Abbreviation: clrhshd_poto.tif
Process_Date: 2009
Source_Produced_Citation_Abbreviation: clrhshd_poto_geo.tif
Process_Step:
Process_Description:
GeoTIFFExamine was then used to open the GeoTIFF to verify the header information and to write a TIFF world file including this information.
Source_Used_Citation_Abbreviation: clrhshd_poto_geo.tif
Process_Date: 2009
Source_Produced_Citation_Abbreviation: clrhshd_poto_geo.tfw
Process_Step:
Process_Description:
The GeoTIFF resulting from the projection of the UTM image to geographic was a 16-bit TIFF image that is not readable by all software. To address this issue, the image was loaded into ArcMap 9.2 and by right-mouse clicking on the image - selected Data Export. The Extend and Spatial Reference are left at the default (Raster Dataset Original), but the Output Raster is set to Use Renderer which automatically checks Force RGB. The Cell Size is left as the default. The resulting image is an 8-bit TIFF 6.0 tiled image.
Source_Used_Citation_Abbreviation: clrhshd_poto_geo.tif
Process_Date: 2009
Source_Produced_Citation_Abbreviation: clrhshd_poto_geo_tmp.tif
Process_Step:
Process_Description:
Not all software is capable of reading tiled TIFF images, so the image was loaded into CorelPhotoPaint version 11 and saved as TIFF with no compression. This had the effect of converting the image from a tiled TIFF to a non-tiled TIFF.
Source_Used_Citation_Abbreviation: clrhshd_poto_geo_tmp.tif
Process_Date: 2009
Source_Produced_Citation_Abbreviation: clrhshd_poto_geo_tmp.tif
Process_Step:
Process_Description:
The image saved from CorelPhotoPaint has no georeferencing information in the header. The file was renamed to the original filename (overwriting the existing file). Then GeoTIFFExamine was used to copy the TIFF world file information from the TFW file into the header of the TIFF image, making the image a GeoTIFF.
Source_Used_Citation_Abbreviation: clrhshd_poto_geo_tmp.tif
Source_Used_Citation_Abbreviation: clrhshd_poto_geo.tfw
Process_Date: 2009
Source_Produced_Citation_Abbreviation: clrhshd_poto_geo.tif
Process_Step:
Process_Description:
For maximum compatibility and ease of use with ArcMap 9.2 and higher, the image was loaded into ArcMap 9.2. The projection of the image was defined using ArcToolbox - Data management Tools - Projections and Transformations - Define Projection. The coordinate system selected was GCS_North_American_1983. Even though the image is a GeoTIFF and there is a world file, this additional step produces an AUX file with all the projection information that is easily read by ArcMap.
Source_Used_Citation_Abbreviation: clrhshd_poto_geo.tif
Process_Date: 2009
Source_Produced_Citation_Abbreviation: clrhshd_poto_geo.aux
Process_Step:
Process_Description:
Edits to the metadata were made to fix any errors that MP v 2.9.32 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Both geographic and a planar coordinate system were present, the planar one was removed. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.
Process_Date: 20160616
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description: USGS Thesaurus keywords added to the keyword section.
Process_Date: 20180720
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description: Crossref DOI link was added as the first link in the metadata.
Process_Date: 20191118
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
Added keywords section with USGS persistent identifier as theme keyword.
Process_Date: 20200908
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
