Creating New Coordinate System

[SaeidHajahmadi]

I have two different coordinate systems and the 2nd order conformal transformation formula, I'm just wondering if it's possible to create a new coordinate system based on these conversions. 

I also have a set of coordinates in both CS if that can be done in Civil 3D. 

I'm uploading the conversion table here if that can illustrate this better.

My goal is to convert from MGA94 to DMG95 and vice versa, we have MGA94 in Civil 3D but need to create DMG95 as well.

I could create a new CS based on this information in Leica Infinity and 3D Office, it has to be a way to create it in Civil 3D as well. 

[Yubari_90]

Never try to do this but I think it's possible with the map 3D commands in the 'planning and analysis' workspace of civil 3D. 
While waiting for someone else to answer and help you more, you can perhaps look here : AutoCAD Map 3D 2023 Help | Create Coordinate System | Autodesk

[Pointdump]

Hi Saeid,
I read through your document on converting AMG84 Coordinates to DMG95 Coordinates. Dense reading that I don't completely understand.
The xls file I sorta understand. The tie points are useful, but I don't understand the x,y,e,n columns.
Your options for geodetic transformation in MAPCSLIBRARY are limited, and I don't see anything that directly relates to your document.
Your best option might be an Affine Projection, something like >>>This<<<.
Dave

[Pointdump · Accepted solution]

Saeid,
Since you had lots of tie points, I created a custom affine projection. I used Excel to calculate the affine parameters. This could be more rigorously done in QGIS, but check things out and see if it will work.
Drawing attached.
Dave

[lim.wendy]

Hi Saeid,

Thanks to Dave for the detailed explanation and providing the .dwg file for you! Dave's solution seems very helpful, and I'm marking his reply as the "Answer" to this thread.

If you have any questions about Dave's approach or need to provide some additional information or feedback, feel free to comment here, and we can unmark the answer to allow further discussion.