Georeferincing issue

[guglielmo_giano9ZYJF]

Hello everyone, 

I learnt through internet that for georefencing i need to refer everything to the UTM system. The softwares that i am using are Autocad 2022 and Google earth pro. Now: i have UTM coordinates on google earth, and i set my geographical location (Autocad) on the coordinates indicated on google earth (see next image):

So far so good: just for curiousity, i wanted to check the coordinates of another point, and i get a noticeable difference:

And guess what: the distances between the 2 points are the same! (circa 830m).

I am extremely confused. I actualy never georeferenced my drawings (and so far no issues, i design electrical plants) and i wanted to start georefencing them as i think it is an important and useful feature.

What i am asking is:

1) The geographical references are different: Google earth is on 33S (i guess WGS84 is the default reference), while on Autocad there are no WGS84-UTM-33S systems. How can i download another system and implement it? Although i noticed: changing systems do not really improve the results.

2) Anynone ever had this kind of issue? the absurd thing is that the distances are the same. I really do not know what to think.

PS: Thx in advance and sorry for my English

Regards.

[pendean]

Plain AutoCAD uses BingMaps.

Most of us with AutoCAD Subscriptions have access to the MAP variant of AutoCAD: do you? here is the link, it may be better suited for your needs https://manage.autodesk.com/products/MAP?version=2022&platform=WIN64&language=EINT

[ChicagoLooper]

Hi @guglielmo_giano9ZYJF 

Thank you for uploading images describing your procedure.

Georeferencing a drawing in vanilla AutoCAD is not that easy because it involves coordinate geometry and requires you to have an understanding that goes beyond the typical user. 

Unfortunately our computer monitors are flat. They are not spherical like crystal balls and we can't view our monitor's display from all sides and from different angles. If we could, then drawing maps would be easier because we'd be able to SEE our linework in a way that's closer to the actual representation of Planet Earth on a spherical surface, not on flat plane.  

You can make the GEOGRAPHICLOCATION function correctly but there's a catch: you need a location on earth, such as a Point, and you must know how to identify that location in two different formats such as (a) Geographic Coordinates and (b) Projected Coordinates. Geographic Coords are expressed in degrees (Lat/long) while Projected Coords are expressed in meters or feet. 

Failure to understand the differences in coordinate systems and how various CS's relate to one another won't allow users to use the GeographicLocaion function correctly. AutoCAD automatically assumes you already have an understanding of coordinate geometry and provides a Toolset but just because you click those icons in the Toolset does necessarily mean you have an understanding of coordinate geometry. It's just saying since you can push a mouse then you must understand all there is know about AutoCAD.

Based on your uploaded images, open a brand new, clean metric template. Then do this.    

1. First, go to Google Earth Pro, then TOOLS=>OPTIONS=>Decimal Degrees=>Meters, Kilometers=>OK

Image-1

2. Right-click on your existing pushpin (the one shown in Post #1 of this thread) and give it a Name, then write down the Lat and Long.

Image-2

<<You will now leave Google Earth Pro but will return to GE Pro later. For now, go to your new AutoCAD drawing.>>

3. In AutoCAD go to INSERT TAB=>Set Location dropdown=>From Map. Next, manually enter the Lat/Long in address section then click as shown below. DO NOT CLICK IN THE 'MAP' AREA. DO NOT CLICK ON THE AERIAL PHOTO .

Image-3

4. Select the coordinate system named UTM84-33N then click as shown. DO NOT CLICK IN MODELSPACE. 

Image-4

<<You will now leave AutoCAD and come back to AutoCAD later. For now, return to Google Earth Pro.>> 

5. Go back to Google Earth Pro. Go to TOOLS=>OPTIONS and make selections as shown then write down Easting and Northing.

Image-5

6. Go back to AutoCAD and go to command line. DO NOT CLICK IN MODELSPACE.

On the command line type in Easting, Northing you just copied for Select a point for the location=>ENTER. Next, type in 90 so your north orientation will be top your monitor=>ENTER=>Your drawing is now georeferenced correctly against the UTM grid, WGS84, zone 33 north. (UTM84-33N units=meters).

Image-6

Both your Lat/Longs degrees and X,Y meters are correct. Turn on Bing aerial imagery. You may now click in modelspace.