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?
Coordinate System Projections (North America > USA > New York > ...):
Working Units/Accuracy Settings:
Using MicroStation V8i SS10, v. 08.11.09.919
Thank you!-- Dave
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.
David Hollner said: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
Oto said:The average correction between NAD27 and NAD83 is an average of 0.349″ northward and 1.822″ eastward
Hmm, that seems like it would make up most the difference. Question is now, is there a way to move the reference of the older survey that distance while keeping it as "Reprojected"?
I think ultimately I'll have to just make it Coincident to the original and reproject it manually. Thanks for the quote about the correction distance.
Oto said:But you could try EPSG:32015 for NAD27 as it has slightly different scale factor.
I tried all other NY East projections that were in feet before posting. None made too much of a difference. One (probably that one) moved a fraction of an inch it seemed; not two feet.
Lorys said:Have you spoken to the surveyor who did the survey
This particular project, I'm personally not sure who it came from nor when the original survey was run. But I remember seeing this with another separate project or two recently where original survey under NAD27 projection didn't line up with newer survey with a NAD83 projection. Question's more generally-speaking than specific. Thanks for the response!
Does anyone where you work have ORD? It has a translation tool for this kind of situation.