NOAA Historical Surveys (T-Sheets)
Purpose and Potential Applications: This data set was featured as base maps to construct nautical charts primarily used for navigation. Current applications include shoreline change analysis and cartographic representation.
Originator(s): National Oceanic and Atmospheric Administration (NOAA) National Geodetic Survey
Abstract: Shoreline surveys—also called coastal surveys, t-sheets or TP sheets, and shoreline manuscripts—refer to topographic sheets compiled from maps derived in the field with a plane table, in the office from aerial photos, or using a combination of the two methods. These shoreline surveys provide the authoritative definition of the U.S. high-water line and may also include details such as roads, prominent buildings, and other features along the coast.
Scale(s): Variable; 1:10,000 to 1:60,000
Coverage: Continental U.S., Alaska, Hawaiian Islands, Puerto Rico, and U.S. Virgin Islands.
Source Data: Topographic sheets
Spatial Reference: Geographic coordinate system (decimal degrees); horizontal datum – North American Datum of 1983 (NAD83).
Tidal Datum: Mean high water and mean low low water
Data Format: JPG
Accuracy: These data are advertised to meet or exceed current National Map Accuracy Standards when plotted as a hard-copy product to the appropriate source chart scale. However, in compiling this derived product, the developers made no attempt to ascertain the congruence between the charted data and the real world.
Process Description: Generation of this shoreline product was accomplished in five stages: data capture, chart cover construction, segment assembly, verification, and final formatting and archiving. Stage 1, data capture, involves the initial conversion of the analog source data, National Ocean Service coastal series navigational charts, into a digital vector image. During stage 2, the raw vector image is converted into an ArcInfo GIS coverage. In addition, during this phase of the work, the data are corrected (gross error removal), topologies are constructed, descriptive information is added, and an intermediate archive is created. The third stage is segment assembly. Here, the chart cover data are partitioned into regionally contiguous groupings (referred to as sections), adjacent boundaries are matched, and the individual charts are joined together to produce continuous shoreline segments. Following assembly, stage 4, data verification, is initiated. Portions of the sectional data are chosen at random to be plotted coincident with chart master sheets (mylars) and compared. Discrepancies are noted, corrective action, if required, is taken, and the data re-verified. The fifth and final stage is formatting and final archive.
Access: The NOAA Historical Shoreline Survey Viewer provides access to a large number of historical shoreline surveys conducted by NOAA and its predecessor organizations. About 7,800 surveys—the earliest dating back to 1841—are available for viewing in Google Earth. In addition to overlaying a scanned image of the survey in Google Earth, the viewer provides links to download: the original scan and metadata, the resulting extracted vector shoreline, and a descriptive report compiled by the survey team.
The following guidance is for users of the shoreline survey Google Earth tool:
- A time slider is available in the upper-left corner. To see a specific time period, slide the handles to define the range of surveys shown in the viewer.
- Click on the outline of a survey to view survey information and to access the preview overlay and source downloads.
- Click on the Preview link to view the preview version of the scan overlaid within Google Earth.
- The Original Scan and World File go together. The World File provides location information for GIS applications, while the Original Scan provides the scan in its original format and original resolution (examples: scan, world file).
- Survey Scan Metadata provides background information on how the scan was completed (example: metadata).
- The purpose of the surveys was to create an accurate shoreline. Thus, the Shoreline Extractand Extract Metadata provide downloads of the vectors extracted from the scans, along with associated metadata (example: vectors, metadata).
- The Descriptive Report provides detailed information from the surveyors (example: T-4371).
- The transparency of the overlaid scan can be changed by selecting the scan in the Places panel and adjusting the opacity slider. This allows the most current Google Earth imagery to be visible with the shoreline survey.
Footprints of the georeferenced scans in the Google Earth file are also available in a GIS shapefile: http://nosimagery.noaa.gov/images/shoreline_surveys/NOAA_Historical_Shoreline_Survey_Footprints.zip. This shapefile contains full URLs to the georeferenced images, world files, descriptive reports, and metadata.
The complete archive t-sheet and TP-sheet Shoreline Survey Scan Archive, which contains 16,200 scans, is available through the non-georeferenced NOAA Shoreline Survey Scans link listed below. The archive lists the original source scans and includes index map catalogs. Of the 16,200 scans, 7,800 were georeferenced and made available through the Google Earth tool. There are no plans to georeference the remaining 8,400 scans. Non-georeferenced NOAA Shoreline Survey Scans
Point of Contact:
NOAA National Geodetic Survey Information Center