.DXF to longitude / Latitude conversion

[phratt]

Hello,

 

First off, I must say that I am not an Autocad user. But one of my friends has a 2008 educational version. Unforyunately he does not do this type of conversion in his job.

 

I need to find out how to convert a .DXF file that contains cadastral (land survey) information so that I can get the coordinates in longitude / latitude of the corners of the property.

 

Can anyone tell me how to obtain the information that I am looking for?

 

Thank you

Phratt

[lpseifert]

Maybe this will help

http://www.dcet.k12.de.us/vault/vault2008/mHOWCONVERTGPSPOINTSCORPSCONAEJEE.pdf

http://crunch.tec.army.mil/software/corpscon/corpscon.html

[phratt]

Thank you lpseifert.

 

Unfortunately I live in Canada. It seems that Corpscon does not work for our neck of the woods.

 

Is there another solution through Autocad? My friend just does not know the commands and if his version of CAD will do the job.

 

Are there freeware that will give me answers out there?

[eldon]

Have you tried Google Earth? if you can find and zoom into the property, you can see the Latitude and Longitude directly

[phratt]

I need to find out how to convert a .DXF file that contains cadastral (land survey) information so that I can get the coordinates in longitude / latitude of the corners of the property.

 

I need to convert a .dxf file.

[eldon]

Perhaps I did not reply in the correct coloured font. I must renew my hearing-aid batteries.

 

As I understand it, you have a DXF file of a survey. This is a Drawing Interchange Format file usually in ASCII format, but could be in binary format. And you want the end result to be Longitude and Latitude coordinates. So you want to convert from a Plane Rectangular Cartesian Coordinate System to a Spherical Polar Coordinate System.

 

This forum has many contributors, who if they don't know the absolute answer, are very willing to suggest a work-around. Repeating the original post in a different coloured font will not get any quicker answers. I wish you the very best of luck in your quest.

[phratt]

Hello Eldon,

 

Being a user of many other forums, I adopted changing the color of the text used as a citation, rather than using the citation function of a forum. To my opinion, the citation function makes the text less readable.

 

I am used to seeing people reading the posts quite fast and then answering either part of the question or just simply changing subjects.

 

There were no bad intentions from my part - sorry if there might be something in what I wrote or did that might be seen as something it was not meant to be. I'll try to be more specific.

 

---------------------------------------------------

 

Back to the subject at hand:

 

Google earth will give you the coordinates to the point that you define on the screen - I need to know and find out what is this point. It does not seem to be a good solution for me, unless there is something I do not know about Google Earth.

 

Someone has said - on another forum - that for Canada, there is a freeware called SYREQ. I have downloaded it, tried it, but I do not understand how I can extract the information to have SYREQ convert it.

 

Does anyone have knowledge of this software?

 

As for Autocad 2008 educational : can it do the job? What are the command lines that will make this exctraction work?

 

Phratt

[lpseifert]

If you get Map (or Civil 3d, which comes with Map) you should be able to do what you need...

Map > Tools > Assign Global Coordinate System/Track Coordinate System

[eldon]

Not being a frequenter of other Forums, I had never seen such colouration as repeated emphasis. (I must get out more!)

 

To the matter in hand. You should try to open your DXF file in AutoCAD. Either it will, or it won't because it has been prepared in a later version of AutoCAD. Opening the drawing will allow you to see what coordinate system has been used to draw up the survey. It could either be a Universal Transverse Mercator system or a local system.

 

I suggested using Google Earth, because at the bottom left of the display, there is a continuous update of Latitude and Longitude coordinates at the pointer. This display can be altered to Universal Transverse Mercator coordinates. If you are fortunate, the aerial shots in the location you are looking for, may be of sufficient resolution, that you can identify ground features. If so, you can read off the coordinates at the corners. I would have thought it unrealistic and not very useful to convert every scrap of information to Latitude and Longitude, bearing in mind that that is a spherical coordinate system and the length of one degree in Latitude is NOT equal to the length of one degree in Longitude, except at the equator.

 

As a side bit of information, even the Latitude and Longitude of the present GPS system was not zeroed when it was set up. There is a "Golden Nail" which an International Treaty defined as the position of the Prime Meridian 0.00°. Google Earth manages to miss this point by over 100 metres, but relatively, the GPS is very accurate within itself.

 

So you can take the complicated absolute way, or take the easy Google Way. In this Forum both might turn up.

[rustysilo]

IF the .dwg is properly set up in regards to the coordinate zone you can set up a point label style in Civil 3D to label the latitude/longitude. You could also set up a point export format if you wanted to export the coords to a text point file.

 

I do not know if regular AutoCAD can accomplish this.

 

Furthermore, with Civil 3D one can also export the .dxf data into Google Earth and then grab the lat/longs there.