Creating a coordinate system

[A_Bell]

How do I create a coordinate system in Map 3D under the define global coordinate system?

We have a local mine grid (x, y, z) coordinate system that we use for our project, which is typical in many mining projects. I have the information to transform this data into UTM NAD27, but I would like to create a coordinate system in AutoCAD so I can attach other georeferenced data such as raster images. We have other projects that have their own mine grid as well so it would help if we could create our own coordinate systems for all of them.

I have read all of the help sections, but they aren't giving me enough information. I have to say that between Map 3D, the internet and the other software I have learned a ton about spheroids, datum, and map projections, but I still don't know how to create my own coordinate system in Map.

Thanks for any help, and Merry Christmas to all,

[greatpanther]

Hi there. Wonder if you ever worked out how to do this. I'm in a similar boat with mines in Mexico and drawings in local coordinate systems which I want to define so I can query in other  drawings.  The help files aren't, these threads haven't provided me with a solution and my local tech support provider is stumped.

Yet it seems like it should be such a simple procedure

[Sinc]

It depends on what you mean by "local coordinate system".

Are you talking about a standard planar coordinate system setup on the surface of the Earth, tied to a projection-based coordinate system like UTM or State Plane?  This sort of system is usually tied to the projection-based Coordinate System via a base point and a "combined scale factor".  If so, then you would need something like the Transformation Tab functionality in C3D.  Unfortunately, that functionality only works with some Civil 3D elements, and no Map commands honor it, even if you're running Civil 3D.  In other words, it can't be done.

But...  You might be able to define an official projection-based Coordinate System that mimics your "local coordinate system" close enough to be useful.  I haven't done it yet myself, but it should work, "in theory"...  The idea is to create a custom coordinate system that is much like your UTM or State Plane zone, except with a scaled-up datum, scaled up by the inverse of the Combined Scale Factor for your project.  Then move your coordinate system origin to try to use convergence to match up your mine grid north with your projection grid north.  Finally, use the False Northing and Easting to get your coordinate values to match up as closely as possible.  There will be error between the two systems, but it might be within "GIS accuracy", so to speak...

The biggest problem with these old mine systems is that they were never really appropriate, due to the amount of vertical change in a mine.  Some of these things have entrances that are a couple thousand vertical feet apart, and now they're trying to use GPS around the mines, and wondering why the old grid systems aren't matching up with the GPS so well.  Of course, it's because of the curvature of the Earth, which was not accounted for in the old mine coordinate systems.

[greatpanther]

Thanks dei-feif for your detailed response. I feel I'm getting a bit out of my depth here. I think that what I need should be very simple. I have an arbitrary grid with a known origin point in UTM.The grid covers a small area and the work is at best sub-metre accuracy so I don't think I need to worry about earth curvature. North is UTM north, east is UTM east. It doesn't seem like it should be complicated to tell the program where this grid sits on the planet's surface. But then, I could be missing something.

B-ag

[Sinc]

If you have a base point near the center of your project, and the mine coordinates for your base point are the same as the UTM coordinates, you can always just try setting the coordinate system to the UTM system, and it might be within your acceptable error limits.

If not, you might be able to create a custom system that will work better, simply by creating a new zone that is like your UTM zone, but with a different factor for the "scale reduction".

If you can give specifics about your coordinate systems, I can help step you through it.  Or if you need to take it offline, you can also contact me via email at "sinc at quuxsoft dot com".

[greatpanther]

Sinc

thanks for your reply, which I'm just seeing now. Don't know how I missed it first time around. After spending the best part of a day on this last month I admitted defeat and moved on to other, more satisfying projects. But my work would be easier if I could sort this out.

Briefly, our mine coordinate system covers a small area, it is assumed to be cartesian with an origin at a known location in UTM zone 13R with grid north as UTM north. I've set up a UCS for this grid but unless I can define this as a coordinate system I see no way to use the automatic grid numbering module for map 2011, and I can't query in data in other coordinate systems.

If you could talk/walk me through this I'd be greatful

Alistair

[Sinc]

After a brief test, it looks like Map commands are similar to C3D commands, and ignore your UCS.  So you can't use a UCS with coordinate systems, and you MUST leave your drawing at WCS.

If you have your drawing in WCS, is everything still at the right coordinates/orientation?  If not, you may need to move everything so that the (X,Y) coordinates in your drawing are the same as the (Easting,Northing) in your Mine coordinate system when you are using WCS.

[neuses]

HI everyone. I need creating or Finding on Autodesk Map3d for ITRF97 coordinate system. what i should do now ???

I wanna ITRF97 to UTM84-48N conversation.....

[antoniovinci]

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neuses wrote:

I wanna ITRF97 to UTM84-48N conversion....

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No prob, sir, you should only set the following CRS upon the _ADESETCRDSYS command:

• EPSG:4918 (as input)

whilst upon the _MAPEXPORT command:

• EPSG:32648  (as output)

[neuses]

th's but that code is  not found... !!!

[neuses]

http://prntscr.com/4c9p3f

http://prntscr.com/4c9pq2

What I should DO noW?

[antoniovinci]

Here's your CRS specifications: http://spatialreference.org/ref/epsg/4918/

[neuses]

th's. But Sorry for me. 

how i install this system on map 3d

Im don't know geodesy knowledge

[neuses]

[antoniovinci]

Press F1 and read all about the ADEDEFCRDSYS command, sir.

In the meanwhile, please zip and upload here your original ITRF drawing, thx.

[neuses]

Sure. I allready reading this section.

But i can't fully complete do this instaletion.

I believe you send me pic instruction. 🙂

[antoniovinci]

Dear sir,
for the second (and last) time, I beg you to zip and upload that EPSG:4918 drawing, thx.

[neuses]

bro. I don;t neew only once transformation. I need dwg file's coordinate system converter of ITRF97 to UTM zone 48N.

My job requered many time's for system transformation... 

[neuses]

sorry my language is bad.

[antoniovinci]

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neuses wrote:

sorry my language is bad.

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Mine is worst, man: without your DWG, I cannot figure out any batch strategy, so good luck...