Switching from northing/easting to latitude/longitude

[Anonymous]

I retrieved the northings and eastings for multiple lights in a model. The model is set up to have northing/easting as my x,y coordinates and z is always zero. I now need to obtain the latitude/longitudes of these lights. I changed the GIS coordinate system to the one i am supposed to be using and set the origin and direction of north correctly, but it is still showing the northings/eastings as coordinates... Essentially how do i change the drawing coordinates to latitude/longitude so i can use the ID command on these points?

[Alfred.NESWADBA]

Hi,

>> I changed the GIS coordinate system to the

>> one i am supposed to be using

Are you using AutoCAD Map 3D or Civil 3D? Or what do you mean by "changed the GIS coordinate system"?

- alfred -

[Anonymous]

I wasn't using a GIS system before and i am supposed to be on MA83F (which i am now set to). But my x,y,z coordinates are still showing northings/eastings. And I am using AutoCad 2018, I know that probably doesn't help my situation as it doesn't contain all the civil tools that map 3D and Civil3D have

[Alfred.NESWADBA]

Hi,

>> I am using AutoCad 2018

May I ask which function/command you used to set the coordinate system to "MA83F", because AutoCAD (Vanilla) does not have such a function.

>> But my x,y,z coordinates are still showing northings/eastings

Well, besides of the question about the product you are using, you should know that lang/long are values measured in degree and not on a plane system (instead it's close to a spherical coordinate description).

A CAD-system can not work with degree as units

A CAD-system might be able to calculate a LL-value from XY knowing the transformation between the 2 coordinate systems, but you won't ever see LL-values in the coordinate display in the statusbar.

AutoCAD Map 3D/Civil 3D have such a command called _MAPTRACKCS as shown here, set to display 3 coordinate systems, first is LL:

- alfred -

[Anonymous]

I went Geolocation> Edit Location> From Map> I then chose the origin to be the same as the current one which is set up for northing/easting to be xy plane. I understand and agree with what you are saying, I think I am going to need to download civil 3D in order to get the latitude longitudes. Thank you for your input and help

[Alfred.NESWADBA]

Hi,

>> I went Geolocation> Edit Location> From Map>

Well, that has nothing to do with the coordinates you have in your dwg-file, it's just a command to show BingMaps aerial image data in the drawings background. Nothing more or less.

>> I think I am going to need to download civil 3D in order

>> to get the latitude longitudes.

Yes, that makes most sense.

If you have AutoCAD with Toolsets, then Map3D is part of that and you can install it.

If you have a suite (like Infrastructure Design Suite) then Civil 3D is part of it and you can install it.

- alfred -

[leeminardi]

You CAN use vanilla AutoCAD 2018 to get latitude and longitude coordinates of points in your drawing.

1. Go to the Insert tab in AutoCAD and click Set Location From Map
   
2. Enter the latitude , longitude of your reference point and then click Drop Marker Here.
3. Click Next and choose a GIS Coordinate system. If your AutoCAD drawing assumes foot units then of course you should select a foot GIS coordinate standard. Click Next.
4. When prompted to Select a point for the location <0,0,0> select your reference point and then accept the angle of 90 if the Y axis is defining due north (otherwise input an appropriate angle)

You should now see your geometry superimposed on a Bing map  of the area (unfortunately, it’s not a Google Earth image).

The next goal is to get the latitude/longitude coordinates of points or polyline vertices in your drawing.  You can do this by adding Mark Position markers at the corners.  First set the marker size and text height with the system variable GEOMARKPOSITIONSIZE

Increase the display precision to 8 decimal places with the UNITS command.

Click Mark Position and then Point.  Now using object snap END add Mark Position points at the locations of interest and label them as desired.

The properties dialog box for Position Markers includes the latitude and longitude of the point. 

You may however want to create a list of the latitude and longitude for all the markers. I typically want these  in the format for use in the kml file (note, there are no spaces in this text string):

  longitude, latitude, elevation (e.g., -91.43636993,40.07972158,0.0).

The elevation value is not important so you can use 0.0 for all the elevations. One way to get this list without the use of a special program is to use the LIST command.  Give the list command and then select the Position Markers.  The output should look like this:

Command: LIST

…

Select objects:

                  POSITIONMARKER  Layer: "0"

                            Space: Model space

                   Handle = 214

Latitude:     40.07829722

Longitude:    -91.43662018

Elevation:    0.00000000

At Point:     X = 105.01359439, Y = 75.41564875, Z = 0.00000000

                  POSITIONMARKER  Layer: "0"

                            Space: Model space

                   Handle = 218

Latitude:     40.07839405

Longitude:    -91.43591676

Elevation:    0.00000000

At Point:     X = 301.87737197, Y = 110.69528986, Z = 0.00000000

Etc.

You could manual cut a paste the coordinates to make a list as text using Notepad, Excel or some other text editor. I wrote the following vlisp program GetKMLCOORDS that outputs the coordinates in the correct KML file format from selected Mark Position points.

-------------  GetKMLCOORDS

;; Prints the longitude and latitude of AutoCAD
;; Position Markers in a KML compatible format.
;;   Original code by Steve Carson
;;   Modified by Lee Minardi 5/24/2019
(vl-load-com)
(defun c:GetKMLdata (/ ss obj)
  (setq ss (ssget '((0 . "POSITIONMARKER"))))
  (repeat (setq i (sslength ss))
    (setq obj (vlax-ename->vla-object (ssname ss (setq i (1- i)))))
    (princ (strcat (vla-get-Longitude obj) "," (vla-get-Latitude obj)
		   "," "0.0\n"
    ))
  )					;repeat
  (textscr)
  (princ)
)					;defun

Side note,  you can use the kml coordinates to complete a kml file you can use to display the points or polylines in Google Earth.

[tcorey]

@leeminardi 's explanation is great for vanilla AutoCAD users.

If you have access to Civil 3D, this will be even easier, as you need only place COGO Points. Each point will list its Northing, Easting as well as Lat, Lon. The points can easily to exported to csv and labeled using automated routines.