Hi Wayne,

There's no surprise in the difference we all see between ortho imagery and World imagery. It's typical.

You'll hear more from Joe Young on this as it's a frequent question he answers when discussing orthometrically corrected imagery based upon real ground-truthed survey data and the work done by the photogrammetrist in wrangling with the roll, pitch, and yawl of the film plane, aerotriangulation, bundle adjustments, etc.

World imagery accessed from ESRI, Google or from any source isn't ortho corrected or tied to surveyed ground control.  But as long as you're aware of its shortcomings and caveats, it is sometimes useful to georeference; i.e., manually rectify, sections of captured World imagery predicated on known geopositional data, including ground survey data and real ortho imagery so long as both the creator and consumer of the work product are on notice as to the diminished positional uncertainties in such a quasi product. This is useful, for example, when the resolution of the ortho image is less than the uncorrected image.

Kind regards,

Kelly

--

Mr. V. Kelly Bellis, ME PLS 2099 :: WQTS485
 17 Union Street :: Ellsworth, ME 04605
http://aerial.panocea.us :: 1+ (207) 667-6912



On 5/20/2018 6:25 PM, Wayne Millen wrote:
[log in to unmask]">

In ArcMap 10.5.1 I am accessing two orthoimagery basemaps from ESRI online--one is the World Imagery the other is one of our State orthoimagery datasets being hosted by ESRI online. I also have downloaded tiles of the state orthoimagery. 

 

I noticed that there are positional differences when comparing the two web map serviced layers--the image shifts about 10 feet when displaying one versus the other.  The tile and web map versions of the state orthoimagery have identical positioning.

 

I would be surprised that this would be normal to have such a displacement in position. What could be causing this issue and how would I either fix it or at least know which data set is causing the issue?  I need to use the state ortho as it is leaf-off and a higher resolution but I am wondering if something may be wrong with its data.  

 

Thanks,

 

Wayne

----------------------------------------------------------------------- This list Maine GeoNews (GEOLIBRARY-L) is an unmoderated discussion list for all Maine GIS Users. If you no longer wish to receive e-mail from this list, you can remove your name and email address yourself at the this web address:

http://lists.maine.edu/cgi/wa?SUBED1=geolibrary-l&A=1

Or,you may also request that your name be removed by sending email to:

[log in to unmask]


----------------------------------------------------------------------- This list Maine GeoNews (GEOLIBRARY-L) is an unmoderated discussion list for all Maine GIS Users. If you no longer wish to receive e-mail from this list, you can remove your name and email address yourself at the this web address:

http://lists.maine.edu/cgi/wa?SUBED1=geolibrary-l&A=1

Or,you may also request that your name be removed by sending email to:

[log in to unmask]