Data misalignment in web application

[SachinChand]

We're having an issue where the data on a web application is not aligning correctly (see attached screenshot).  We are using ArcGIS 10.2.  When pulled up in the web application, however, the alignment is a bit off as seen in the screenshot.  The web application uses two services, one cached and one dynamic.  The misalignment is coming from the dynamic service.  Any ideas on what the cause could be?  I'm not a javascript/web developer so I may need a layman response 🙂

The things I've tried so far is republishing the services after upgrade to 10.2, trying several browsers and clearing browser caches.  I've also verified the the issue is not with the data or the map service as the data is correct and the map service also displays with correct alignment.  The projection of the map services and the web app also match.

Thank you

[JohnGravois]

what are the coordinate systems (and more importantly underlying datums) of the two services?

[SachinChand]

what are the coordinate systems (and more importantly underlying datums) of the two services?

Thank you for the response.  Below is the coordinate system information.  The application is the "Campus Place Finder" local government template from the ArcGIS Resource Center ( http://www.arcgis.com/home/item.html?id=2eb8d58bdc2246e1b101d6c01eb62023 ).  We are using all ArcGIS v10.2 products and the application is v10.1.  Would that be an issue?


WGS_1984_Web_Mercator_Auxiliary_Sphere
WKID: 3857 Authority: EPSG

Projection: Mercator_Auxiliary_Sphere
False_Easting: 0.0
False_Northing: 0.0
Central_Meridian: 0.0
Standard_Parallel_1: 0.0
Auxiliary_Sphere_Type: 0.0
Linear Unit: Meter (1.0)

Geographic Coordinate System: GCS_WGS_1984
Angular Unit: Degree (0.0174532925199433)
Prime Meridian: Greenwich (0.0)
Datum: D_WGS_1984
  Spheroid: WGS_1984
    Semimajor Axis: 6378137.0
    Semiminor Axis: 6356752.314245179
    Inverse Flattening: 298.257223563

[JohnGravois · Accepted solution]

Sachin,

since both these coordinate systems reference the same underlying datum, no shift should be expected.

i'm not positive, but i have a hunch that at least one of the datasets in the map service which is reprojecting on the fly actually has its own differing coordinate system with different underlying datum and that no datum transformation to WGS84 was defined in the map document prior to publishing.

[SachinChand]

John, thanks for the response.  If that were the case, would the misalignment show up in the map service?  I should also mention that the application aligning correctly.  I only noticed the shift after upgrading to 10.2.  It is possible the shift occurred prior to the upgrade but I only noticed it after.

[JohnGravois]

how could you judge alignment until you were overlaying two different services?

i could be wrong, but i doubt that version compatibility is the problem here.

[SachinChand]

how could you judge alignment until you were overlaying two different services?

i could be wrong, but i doubt that version compatibility is the problem here.

The alignment issue is on one service.  The lines and polygons you see misaligned in the screenshot are from the same service.  The second service is a cached basemap.

[JohnGravois]

ahh! thanks for clarifying 🙂

if thats the case, the same misalignment should appear in the REST service's JavaScript Viewer and even in the map document used to publish the service.

can you confirm whether or not that is the case and check the coordinate system of the actual data?

[SachinChand]

ahh! thanks for clarifying 🙂

if thats the case, the same misalignment should appear in the REST service's JavaScript Viewer and even in the map document used to publish the service.

can you confirm whether or not that is the case and check the coordinate system of the actual data?

Sorry for the confusion 🙂

The misalignments don't show up anywhere but the application.  They are aligned correctly in the JS viewer and the map document.  The coordinate system of the actual data is:
Projected Coordinate System: NAD_1983_StatePlane_Maryland_FIPS_1900_Feet
Projection: Lambert_Conformal_Conic
False_Easting: 1312333.33333333
False_Northing: 0.00000000
Central_Meridian: -77.00000000
Standard_Parallel_1: 38.30000000
Standard_Parallel_2: 39.45000000
Latitude_Of_Origin: 37.66666667
Linear Unit:  Foot_US

Geographic Coordinate System: GCS_North_American_1983
Datum:  D_North_American_1983
Prime Meridian:  Greenwich
Angular Unit:  Degree

[JohnGravois]

are your services and/or app public?
how badly are the layers misaligned?

are you saying that both the cached basemap and dynamic map service are published in web mercator, and that your dynamic map service layers only become misaligned in that particular app?

i have a couple different suggestions.
1. compare the exportMap requests and responses for the problematic layer between the JavaScript Viewer and the Campus Viewer application to see if anything relevant seems different.
2. try defining a datum transformation between NAD83 and WGS84 in your map document prior to republishing the service.