Different Geographic Projections from Two Files are Slightly Offset From Each Other

Hello forum!

I have two survey files.  One older survey uses an older state projected geographic coordinate system and the newer survey uses a newer projected GCS.  When both are referenced into a mutual file (both Geographic-Reprojected), all points are 1.5–2 feet off from each other, give or take.  Using any other projection on one doesn't come much closer.

Is there a way to adjust a setting somewhere to make them fall closer together, since reprojected references aren't allowed to be moved?  Or, is this the closest they can get?

  • Assume I cannot have one's survey coordinates rerun under the other's coordinate system.
  • See attached image.  (I work for a company that may not allow me to attach design files.)
  • Changing "Reference Reprojection Settings" to Yes or If Spatially Large, or the method to AEC Transform, appears to make no difference.

Coordinate System Projections (North America > USA > New York > ...):

  • Older survey:  "NY-E - NAD27 New York State Planes, East Zone(3101), US Foot" -- 2nd from the top for me.
  • Newer survey:  "NY83-EF - NAD83 New York State Planes, East Zone, US Foot" -- 6th from the top for me.  Project files will use this projection.  I am working about 1,025,000+ feet from global origin.

Working Units/Accuracy Settings:

  • Survey Feet (SF) Master Units
  • Resolution:  1000 per Distance Survey Foot
  • Working Areas:
    • Total:  1,705,912,362 Miles
    • Solids:  813.442402 Miles (4.29497 e-5 SF accuracy)

Using MicroStation V8i SS10, v. 08.11.09.919

Thank you!
-- Dave

Parents
  • I read this: Depending on where you are in North America, NAD27 and NAD83 may differ in tens of meters for horizontal accuracy. The average correction between NAD27 and NAD83 is an average of 0.349″ northward and 1.822″ eastward

    But you could try EPSG:32015 for NAD27 as it has slightly different scale factor.

  • One older survey uses an older state projected geographic coordinate system and the newer survey uses a newer projected GCS.  When both are referenced into a mutual file (both Geographic-Reprojected),

    Have you spoken to the surveyor who did the  survey they may be able to suggest a better datum with lower scale factor  or they  might do a better transformation  for you...

    Lorys

    Started msnt work 1990 - Retired  Nov 2022 ( oh boy am I old )

    But was long time user V8iss10 (8.11.09.919) dabbler CE  update 16 (10.16.00.80) 

    MicroStation user since 1990 Melbourne Australia.
    click link to PM me 

Reply
  • One older survey uses an older state projected geographic coordinate system and the newer survey uses a newer projected GCS.  When both are referenced into a mutual file (both Geographic-Reprojected),

    Have you spoken to the surveyor who did the  survey they may be able to suggest a better datum with lower scale factor  or they  might do a better transformation  for you...

    Lorys

    Started msnt work 1990 - Retired  Nov 2022 ( oh boy am I old )

    But was long time user V8iss10 (8.11.09.919) dabbler CE  update 16 (10.16.00.80) 

    MicroStation user since 1990 Melbourne Australia.
    click link to PM me 

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