Friday, August 12, 2016

Create a Shape File With Data For GIS From AutoCAD

AutoCAD users know how to create geometric objects.  And we know how to label them.  But how do you attach data to those objects to export together for use in GIS?  You can do it if you can put your drawing on a public coordinate system and you have AutoCAD Map.  And you don't have to become a GIS expert or even learn a new interface.


1.  Your AutoCAD installation must have the following commands available:

2.  You must assign a geographic coordinate system to your drawing to interface with global latitude and longitude.  You must have the ADESETCRDSYS command available.  This is easiest if you choose a public coordinate system early and set it using a program like Civil 3D.  There is no way around this, because GIS is inherently built around being globally correct about coordinate systems.  You can check your coordinate system by using the GEOMAP command (if you have it) to make sure you really are where in the world you think you are.


What we are going to do is
1. Define AutoCAD data "tables" with fields (like columns)
2. Attach the AutoCAD tables to AutoCAD objects
3. Fill out the data fields for each object
4. Export the AutoCAD objects with AutoCAD data to a GIS shape file with GIS tables.


Let's attach and export Parcel Name and Parcel Zoning data to some polylines. We will create a PARCEL table with a NAME column and a ZONING column.


Use the ADEDEFDATA command:

Enter the table name "PARCEL".

Enter a field name "NAME", choose Character as its Type, and click Add.

Enter another field name "ZONING", choose Character as its type, and click Add again.

(You may have to click outside the Field Name box to get the Add button active.)

Click OK to finish the definition of this data table.

Click Close to finish defining tables.


Use the ADEATTACHDATA command:

Click Attach to Objects <, then select the object to have the data attached.


Fill in the data for each object using PROPERTIES.


Make a folder for your GIS export.  I will export to the Desktop\GIS-Parcel folder.

Use the MAPEXPORT command:

Choose ESRI Shapefile (*.shp) file type, browse to the place you want to put your export, and enter "Parcel" for the Shapefile name.

In the Selection tab of the MAPEXPORT form, I chose Polygon and Select manually.  Then I picked the polylines that have the data.

In the Data tab of the MAPEXPORT form, click Select Attributes.  Expand Object Data and pick the fields you want to export.  Then click OK.

Click Create Unique Key Field to be polite to your GIS person so there is a unique id for each polyline.

In the Options tab of the MAPEXPORT form, hopefully you can leave your Coordinate conversion as you previously set it.  To be polite to your GIS person, check the box to treat closed polylines as polygons.  Then click OK.

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