Type Shapefile
To show a base layer of Yap.
This dataset shows the land area of Yapand its lagoon islands, as well as the reef and lagoon area. It was createdby Island Research & Education Initiative (iREi) based on Digital Line Graphs (DLGs) from U.S. Geological Survey 1:25,000-scale topographic maps. The shoreline and reef areas were shifted and adjusted to follow current imagery better. In urban areas, the shoreline was updated using WorldView-3 satellite imagery from Digital Globe (2016) provided by U.S. Department of Agriculture (USDA) - Natural Resources Conservation Service (NRCS).
Original dataset by U.S. Geological Survey (USGS) Updated by Island Research & Education Initiative (iREi)
There are no expressed warranties associated with the release of these databases. Specifically, no warranty is made that the GIS data or any subsequent updates will be error free and no warranty is made regarding the positional or thematic accuracy of the GIS data. The GIS data and any features it depicts do not represent or confer any legal rights, privileges, benefits, boundaries or claims of any kind.
There is no extent for this item.
There is no scale range for this item.
The dataset is included in the Digital Atlas of Micronesia, module Yap, by Island Research & Education Initiative (iREi) in collaboration with Water and Environmental Research Institute of the Western Pacific (WERI) at the University of Guam and funding from United States Geological Survey (USGS) under WRRI 104-B Program and FSM Department of Environment, Climate Change & Emergency Management (DECEM).
Original dataset by U.S. Geological Survey (USGS) Updated by Island Research & Education Initiative (iREi)
There are no expressed warranties associated with the release of these databases. Specifically, no warranty is made that the GIS data or any subsequent updates will be error free and no warranty is made regarding the positional or thematic accuracy of the GIS data. The GIS data and any features it depicts do not represent or confer any legal rights, privileges, benefits, boundaries or claims of any kind.
Topological requirements include the following: lines must begin and end at nodes, lines must connect to each other at nodes, lines do not extend through nodes, left and right areas are defined for each line element and are consistent throughout the file, and lines representing the limits of the file (neatline) are free of gaps.
The completeness of the data is unknown but should be consistent with the level of information normally shown on U.S. Geological Survey 1:24,000-scale topographic maps.
Attribute accuracy is tested by manual comparison of the source with hard copy plots and/or symbolized display of the digital line graph on an interactive computer graphic system. Through inspection and queries, attempts were made to ensure completeness and consistency of attribute values.
The updated sections (mainly around Kolonia and Sokehs) are accurate within a few meters, the other areas are accurate within about 20-30 meters.
Visual comparison with WorldView-3 satellite imagery.
1. Edited reef polygons (extracted from Digital Line Graphs by USGS) to better match 2016 WorldView-3 satellite imagery by Digital Globe. 2. Combined with new shoreline data by iREi 3. Created barrier reef and lagoon polygons 4. Checked topology 5. Formatted attribute table and added fields (name, source, etc).
To create an updated base layer for Yap.
yap_shoreline
Feature geometry.
ESRI
Coordinates defining the features.
Internal feature number.
Esri
Sequential unique whole numbers that are automatically generated.
Area in acres
Source of original dataset.
Area in square kilometers
Area in square meters
Area in square miles
The USGS document Standards for Digital Line Graphs, Part 3: Attribute Codes, contains a detailed description of each attribute code and a reference to the associated map symbols on the map source materials. The document is available at http://rockyweb.cr.usgs.gov/nmpstds/acrodocs/dlg-3/3dlg0798.pdf. Other DLG Standards are available from http://rockyweb.cr.usgs.gov/nmpstds/dlgstds.html.