I have a large (equivalent to size of Ireland) line feature class (fc) depicting a shoreline, which I am editing. The shoreline is in Alaska State Plane Zone 1 (meters), NAD83. The NAD83 realization is closest to NAD83(1986) or NAD83(CORS96). The shoreline is in an ArcMap document. The dataframe is set to Alaska State Plane Zone 1 NAD83 [EPSG26931]. I am using ArcMap v. 10.1 on Windows 7.
I have two DigitalGlobe (DG) map services in the ArcMap document:
1) DigitalGlobe Web Map Service:Imagery, which is served in WGS84 [EPSG: 4326], and comes with an option to alternatively receive the image in WGS84 Web Mercator (auxiliary sphere) [EPSG: 3857].
2) DigitalGlobe:ImageryTileService, which is served in WGS84 World Mercator [EPSG: 3395]
I have no idea which realization of WGS84 is represented in these orthos.
I would like to be able to use the DG ortho-imagery for digitizing new shoreline information and to update existing lines in the NAD83 shoreline fc. The problem is getting the 3 data sources to line up. For the dataframe properties I have specified the WGS_1984_(ITRF00)_To_NAD_1983 transformation.
--I have some lines in the NAD83 shoreline digitized from in-house orthophotos that are also in State Plane AK Zone 1, NAD83. These features are about 8 meters off from the DG Imagery and 10 meters off from the DG TileService. However this could be explained by spatial inaccuracies from the orthorectification.
--The DG Imagery and DG TileService orthos are about 12 meters off from each other. It seems I should be able to get these 2 sources to align with each other.
1) Is there a transformation to align two images in WGS84 [EPSG 4326] & WGS84 World Mercator [EPSG: 3395]?
2) Can I align EPSG 4326 & 3395 with NAD83?
Many thanks to anyone who can help.