AutoCAD Civil 3D

[#1]

Im working in acad c3d 2013. To help my question be easier to follow, open a drawing, on the tool space click the settings tab, right click on the top folder/drawing name, click edit drawing settings.

If I edit the drawing settings  to the Zone- USA, Texas, and the cood system to nad83 Texas State Plane, North Central Zone, US Foot, then it changes the imperial to metric conversion to US survey foot. then when I bring in my points they are about 15 feet off.

If I set the Zone to NO Datum, NO Projection  and the Imperial to Metric conversion to International foot , then they come in correct.

Can anyone explain this. I thought it should be in nad 83. As far as I know the survey equipment is set up correctly.

[#2]

The difference you are seeing in your coordinates is due to the US-Foot/Int-Foot conversion.  The difference is only 2ppm, but when applied to the large coordinate values of this zone it equals the 15-foot displacement.

What foot unit is the data using?  What are you comparing the imported points to that you know it is "off" when the foot unit is changed in the drawing? 

[#3]

Hi,

Are you doing the import using the Survey? or just are importing a file of points (N, E, Z) .....

If using the Survey, then you need to do the configuration of units with command AeccEditSvDatabaseSettings.

[#4]

Stacy- It Defaults to US Survey Foot when I pick TX83-NCF for my coord system,

It works perfect with international foot but what else does the "no datum" affect?

I am using the control point N&E off the field notes to check if its in the correct location. plus its really obvious when its layed over the topo map

Adriano- the settings are set to no datum

[#5]

The foot unit should be US-Foot when selecting TX83-NCF.

The zone must be set to allow Civil 3D to calculate grid coordinats, Lat/Long and grid distances.  The zone information is also used to transform GIS data, data from a survey database, and point data where the file format contains zone information.

It is important that you know what units/zones your data is using and what the settings your drawing and survey database are using.  If your survey database is set to USFoot and the drawing is set to International Feet, the data will be adjusted when inserting it into your drawing.  Civil 3D expects you know what you are doing and doesn't warn you that the adjustments are being made.

If this is a new project I would verify that all of your data has been imported into the drawing correctly.  If this is an existing project, you may be better off leaving the zone off and continuing with the current coordinate system.

[#6]

I can only get it to come in correctly with the drawing settings set to international foot, no datum-no projection

It doesnt change anything when I edit the survey database settings.

The weird part about it is its been working fine on the nad 83 setting- us foot so I am wondering if there is another setting somewhere. We had trouble about a year ago with one project, I dont know what I did to fix it and today I cant get any of them to work.

[#7]

I am guessing here, but is it possible that the coordinates you are importing are using the wrong foot unit?  Can you compare the coordinate value of the original file to the one you end up with in C3D and see if something has been adjusted in the import process.

[#8]

How are the coordinates being added to the drawing? From points import or a survey database? Can you post the coordinate file or a portion of it?