topic Re: "base" coordinates keep randomly changing in Civil 3D Forum

"base" coordinates keep randomly changing

Anonymous — Wed, 15 Aug 2018 17:38:27 GMT

I have a drawing set to State Plane coordinates. I'm trying to keep the "base" coordinates at 0,0,0. However, everytime I open the drawing, the "base" coordinates change to some seemingly random coordinates (

-12027991.7924,-4199948.5914,19). I have no idea what is causing this shift. This project has several x-refs (also in the same coordinate system), and the xref insertion x,y,z is also changed to this number. So every time I open, I have to set the xrefs back to 0,0,0 and move all my linework from the random x,y,z back to 0,0,0. I'm also using pipe networks, so the elevations are crucial. It's worrisome that even the Z coordinate on the xrefs are changing.

Any idea what is causing this?

Re: "base" coordinates keep randomly changing

tcorey — Wed, 15 Aug 2018 18:32:13 GMT

In drawing settings, Transformation tab, is transformation turned on?

Re: "base" coordinates keep randomly changing

Anonymous — Wed, 15 Aug 2018 18:44:15 GMT

Here is what I have on the Transformation tab,

Re: "base" coordinates keep randomly changing

spear_kevin_pe — Wed, 15 Aug 2018 18:46:54 GMT

other culprits could be...
-custom lisp for that project that sets the base system variable
-UCS

Re: "base" coordinates keep randomly changing

ChicagoLooper — Wed, 15 Aug 2018 20:51:34 GMT

Putting your drawing in the appropriate State Plane is admirable. If your xrefs are referenced to the correct State Plane then those xrefs should be correctly positioned relative to 1) your basemap, 2) relative to the other attached xrefs, and 3) relative to Bing Satellite Maps. This is true because they are all referenced to the same 0,0 point (which was determined by the correct Zone in the correct State Plane).

To test, first open a clean, fresh drawing using an out-of-the-box imperial or metric template. Second, assign your State Plane CS with the correct Zone. Third, attach your xrefs one-at-a-time, insertion point=0,0, scale=1.0, and rotation=0 degrees. Fourth and finally, turn on Bing aerial imagery and everything should be in harmony. If not, then you have issues.

Notes:

The most common reasons for inconsistent positioning of line work are, but not limited to: incorrect coordinates assigned to modelspace, incorrect CS used when drawing the xref or the basemap, UCS orientation not set to 'world,' C3D/M3D considers the CS as 'unknown' (such as when using a site specific or local datum), insertion scale errors (inches vs feet vs meters vs millimeters), and the original author falsely claiming his drawing was correctly georeferenced, when in fact, it was not.

Re: "base" coordinates keep randomly changing

Anonymous — Wed, 15 Aug 2018 21:13:25 GMT

All my xrefs are in the same State Plane CS. Actually all my files are derived from the same source drawing which is also set up in the correct CS.

I'm wondering, could it be that whats causing the issue is that "0,0" base point is far from my work area?

In any case, why does the "base" coordinate numbers change in the first place when I reopen the drawing, even though I set it to be 0,0,0?

Re: "base" coordinates keep randomly changing

ChicagoLooper — Wed, 15 Aug 2018 21:48:50 GMT

No, being far away from 0,0 point, or the origin, is not the issue. All State Planes have coordinate values in the one-hundred thousandths as well as greater than 1 million. No matter the State Plane, with US Survey feet as the units, you will not find neither x- nor y-coordinate below 100,000. That is the nature of State Plane.

What does 'Derived from the same source drawing' mean? Who is the author? Your full disclosure will determine whether you really want to solve this.
What is the State Plane and Zone for your xrefs? E.g. Ohio has 2 zones, north and south. Indiana has 2 zones, east and west. Texas has 5 zones. California has 6 zones. Alaska has 9 zones. States like Tennessee, North Carolina, and New Jersey have only one zone which covers their respective State.
What is the coordinate system you have assigned to modelspace?

The origin is not moving. If it is, then you have successfully undermined AutoCAD and the industries that use AutoCAD.

Re: "base" coordinates keep randomly changing

Anonymous — Wed, 15 Aug 2018 21:55:16 GMT

Original/source drawing is a basemap from GIS data converted to CAD linework (property lines and curbs).

Coordinate system is CA State Plane Zone III, US Foot

Re: "base" coordinates keep randomly changing

Anonymous — Wed, 15 Aug 2018 21:57:16 GMT

Re: "base" coordinates keep randomly changing

ChicagoLooper — Wed, 15 Aug 2018 22:03:20 GMT

Great, we are making progress. You need to good to the folder with the shapefile. Double click on the .prj file so it opens in Notepad, then take a screenshot of the contents.

Then next thing will be to check your work flow to 'bring in' the shapefile. Are you using an FDO connection to bring in map features? Or are you using MAPIMPORT to convert the shapefile into Cad entities? But before anything else, need screenshot of the prj.

Re: "base" coordinates keep randomly changing

Anonymous — Wed, 15 Aug 2018 22:11:59 GMT

I'm using a program that connects directly to our GIS database from Autocad and converts the GIS data into cad linework for the specific area queried (I work for city gov and we maintain the database). So I don't have a shapefile or prj file for this particular project.

Re: "base" coordinates keep randomly changing

ChicagoLooper — Wed, 15 Aug 2018 22:56:16 GMT

OK. You are doing work for the DOT or a similar agency. Do what you're doing, or what you did, but this time don't use your Department's standard issue template. Open a fresh clean drawing using No template-Imperial.

No Template - Imperial

You want to use No Template then attach your xrefs because DOT templates are notorious for having settings 'built-in' and these settings can adversely affect your line work when you insert or attach Cad entities. By using No Template you 'liberate' yourself from those settings.

Also, is it possible to verify whether the GIS data is using California State Plane, NAD83, Zone 3, US feet and not something else, like WGS84 Lat/Long degrees or UTM-meters?

You have also assigned CA83-III US feet to modelspace and I assume it is the correct CS. Your 'input' CS can be anything appropriate given the xref's location, the input CS dorsn't have to be the same as the resultant CS in modelspace-Cad will perform the required transformation between input and resultant. As long as the input and resultant CS's are appropriate and are in the Cad coordinate system library, the transformation will be successful.

Re: "base" coordinates keep randomly changing

Anonymous — Thu, 30 Aug 2018 18:14:21 GMT

Okay, I copied my file to a new blank drawing. I also used the lidar survey for this area as a data reference, and tied my pipe network to this topo for the rim elevations. This seems to resolve the issue. Thank you!