Latitude Longitude Collection Method

[mconway]

I have a User being asked By the Department of Conservation and Natural Resources (DCNR) here in Pennsylvania, USA, "What Method we are using to Calculate our Latitude and Longitude Coordinates." 

We "Traditional" Surveyed the Area and then used Civil 3D to convert the CoGO Point Info to Lat/Long. 

Does anyone know what method Civil 3D uses for this conversion or where i might find that info? the options are in the attached image... 

[ChicagoLooper]

Hi @mconway 

Your question is too vague, there's not enough info to answer it. You'll need to explain in words that don't include the term traditional. 

It would help to know the file format (file extension) you received from your surveyor. Better yet, can you share that file? 

[mconway]

The file is a PNEZD (Comma delimited) .txt file based on a PA83-SF Coordinate System. The CoGo Point come into the drawing that is Set to that Coordinate System. When Hovering on the CoGo Point, the software returns a Latitude and Longitude. What method is Civil 3D using to determine the Latitude and Longitude conversion from the PA83-SF Coordinate System?  

Traditional meaning they used a Total Station not a GPS Collector or LiDAR. Sorry for the local terminology 

[ChicagoLooper]

It would be helpful to see the output file created by the surveyor. The field crew has projected their field shots in a known projection. That projection is unknown (or you are unwilling to disclose it). It could be WGS84 datum (EPSG4326), NAD83 datum (EPSG 4629), Mercator WGS84 (EPSG 3857) or even something else. From the field crew's projection, you re-projected it to PA State Plane and Zone, NAD83, feet, and put the survey into your drawing. Then, from your civil drawing, you get the Lat/Longs. 

It went from the field crew=>>to your C3D PA State Plane drawing=>>then finally to Lat/Longs.

What does this mean? It means the final coordinates, the Lat/Longs, are only as good as your ability, AND confidence, to convert them into geographic coordinates in decimal degrees (or degrees-minutes-seconds). If your conversion is spot on, then your Lat/Longs are correct. If, however, you made an error(s), then your Lat/Longs are incorrect. 

So far you've managed to project the C3D survey drawing into PA state plane/zone-feet using the survey data. So........what did the survey start as? What did you receive from the field crew? You simply can't put the survey into PA State Plane if you don't know what the field crew handed you in the first place.  

Here are two easy tests you can use the determine if your Lat/Longs derived from your PA State Plane drawing are correct.

TEST 1:

If you turn on Bing aerial imagery in modelspace, is the aerial background consistent with your linework? Can you upload a screen shot of the drawing with Bing in the background?

TEST 2:

Draw a rectangle around your site. Then, export that rectangle to KML.

Go to Toolspace=>Toolbox Tab=>Misc Utilities=>Export KML=>Expand KML=>Right click KML=>Execute.

Follow the prompts and open the exported KML in Google Earth Maps. 

Does the KML land in the right spot? 

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