{ "currentVersion": 10.7, "serviceDescription": "The 1949 shoreline was digitized from historic aerial photography that were orthorectified in ERDAS by the Shoreline Studies Program and the 2017 shoreline was digitized from the Virginia Base Mapping Program (VBMP) orthophotography for Chesapeake Bay region in Virginia. The 2017 digital orthophotography was acquired and processed by VBMP.\n\nUsing methodology reported in Morton et al. (2004) and National Spatial Data Infrastructure (1998), estimates of error in rectification, control source, DEM and digitizing were combined to provide an estimate of total maximum shoreline position error. These data sets have an estimated total maximum shoreline position error of 20.0 ft, while the total maximum shoreline error for the three existing datasets are estimated at 18.3 ft for USGS and 10.2 ft for VBMP.\nAny inaccuracies are due to any misalignment from poor photo quality, physical condition of each aerial photograph used, tree cover on banks, time of tide when the photos were taken, and errors in positional accuracy.\n", "mapName": "Layers", "description": "", "copyrightText": "Shoreline Studies Program at Virginia Institute of Marine Science", "supportsDynamicLayers": false, "layers": [ { "id": 0, "name": "Eastern_Shore_Marsh_1949", "parentLayerId": -1, "defaultVisibility": false, "subLayerIds": null, "minScale": 0, "maxScale": 0, "type": "Feature Layer", "geometryType": "esriGeometryPolygon" }, { "id": 1, "name": "Eastern_Shore_Marsh_2017", "parentLayerId": -1, "defaultVisibility": false, "subLayerIds": null, "minScale": 0, "maxScale": 0, "type": "Feature Layer", "geometryType": "esriGeometryPolygon" } ], "tables": [], "spatialReference": { "wkid": 26918, "latestWkid": 26918 }, "singleFusedMapCache": false, "initialExtent": { "xmin": 333394.0198837151, "ymin": 4141715.1288221865, "xmax": 558168.403516285, "ymax": 4214074.005745, "spatialReference": { "wkid": 26918, "latestWkid": 26918 } }, "fullExtent": { "xmin": 412687.4989, "ymin": 4104390.5701, "xmax": 478740.1892000003, "ymax": 4208852.040999999, "spatialReference": { "wkid": 26918, "latestWkid": 26918 } }, "minScale": 0, "maxScale": 0, "units": "esriMeters", "supportedImageFormatTypes": "PNG32,PNG24,PNG,JPG,DIB,TIFF,EMF,PS,PDF,GIF,SVG,SVGZ,BMP", "documentInfo": { "Title": "", "Author": "", "Comments": "Rectified the 1949 aerial imagey and digitized the marsh along with other features on the ocean coast side. The outlines were then converted to polygons and attributed.\nThe 2017 images came from VBMP but SSP digitized them as outlines as well and then converted them to polygons. ", "Subject": "Eastern Shore ocean side marsh for 1949 and 2017, used to compare erosion and accretion for this time period", "Category": "", "AntialiasingMode": "None", "TextAntialiasingMode": "Force", "Keywords": "Shorelines,marsh,ocean side,Accomack,Northampton" }, "capabilities": "Data,Map,Query", "supportedQueryFormats": "JSON, AMF, geoJSON", "exportTilesAllowed": false, "supportsDatumTransformation": true, "maxRecordCount": 1000, "maxImageHeight": 4096, "maxImageWidth": 4096, "supportedExtensions": "KmlServer" }