[V8i] GeoJPG not quite in the right place?

I have a survey (INHP-EF), and I have a georeferenced JPG file (GCS EPSG:3857). They aren't QUITE on top of each other. The image is "north" a couple of feet.

Is this possibly some sort of unit mix-up?

Or is it more likely that whatever datum the surveyors used is slightly off from whatever is governing the image?

What else can I do to check that everything is coming in exactly where it is supposed to?

My engineer is asking me why they don't match up exactly and I might be losing hair.

Parents
  • Hi Mary, can you try a little experiment?

    go to your working drawing ref attach your survey ( you already have units and  GCS set) so set your view to the extent  you want covered.

    now go to the google pro earth synchronise and is the image good enough for your needs in google earth?

    can you kmz to see it is where you think it should be? Did your survey match exactly on the image... ? Ok then you confirmed that your original image is  off and not the survey..

    You could  go to your holding  file that has the jpg, attach the  survey and  correct the image through the warp tools using as many points as possible  around the outer edges or as many observable points as possible then when your satisfied , in the raster manager select the raster and  under the file  save as GEOTIFF..

    Now you can use the new GEOTIFF as  your adjusted raster, without the sister file from the jpg...

    Alternatively you could create empty 3d drg and exref your survey  fit view to your needs, turn off survey , now goggle earth syncro and use the google earth capture tool this will create the mesh you can now trace create a polygon around the mesh extents  to ref attach downloaded capture of google earth later, go to the google view and use the download image / save image tools... if you haven't  changed view and zooms the down load will be a perfect match of the mesh polygon,  you can delete mesh but leave the boundary you drew..

    Ref attach the 3d drg  with polygon to your drg that  has the old raster( switch the old raster  off for now detach later) , now through the ref manager  ref attach interactive to match the polygon the new downloaded  raster from google earth pro ( its in colour now), now export to geotiff and you now have a new raster to replace your  old one and its the right coordinates and will  land in the right location without the need of a sister file ( JGW) ...this should now be perfectly aligned to the survey..

    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 

    Answer Verified By: MaryB 

  • After some more experimentation, the survey doesn't line up with the image, or any image.

    In addition to the GeoJpg I was provided, I have now also (as Lorys suggested) checked against Google Earth, both by bringing in a Google Earth image and by exporting my DGN to KML/KMZ; I have also checked against Bing Maps. I see the same "offset" with everything. I also have the survey in AutoCAD, and it relates to any geo-referenced imagery the same way.

    I don't think it's that big a deal - at the coordinates we're discussing, I wouldn't be surprised if there's just some rounding difference between the image sources and the surveyor's datum.

    MaryB

    Power GeoPak 08.11.09.918
    Power InRoads 08.11.09.918
    OpenRoads Designer 2021 R2

        

Reply
  • After some more experimentation, the survey doesn't line up with the image, or any image.

    In addition to the GeoJpg I was provided, I have now also (as Lorys suggested) checked against Google Earth, both by bringing in a Google Earth image and by exporting my DGN to KML/KMZ; I have also checked against Bing Maps. I see the same "offset" with everything. I also have the survey in AutoCAD, and it relates to any geo-referenced imagery the same way.

    I don't think it's that big a deal - at the coordinates we're discussing, I wouldn't be surprised if there's just some rounding difference between the image sources and the surveyor's datum.

    MaryB

    Power GeoPak 08.11.09.918
    Power InRoads 08.11.09.918
    OpenRoads Designer 2021 R2

        

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