James D. Carroll


More info:

Refer to the links below to learn more about the use of different ArcMAP tools and resources.


- Georeferencing Toolbar

- Feature Class
to Feature Class Tool

- CAD to Geodatabase Tool


AutoCAD Intergration

The Problem

This exercise introduced the capabilities of ArcGIS to integrate non-native CAD file format and data into the ArcMAP geospatial analysis process. The emphasis is on the use of the tools for georeferencing and translating CAD datasets into ArcMAP.
The specified problem is to georeference a "CAD.dwg" file to the "Orthophoto.SID" file for the NCSU campus area, export the required CAD layers into a new File Geodatabase, analyze for errors, repair geometry as necessary, and output building polygon features for analysis required for future campus facilities management.


To georeference the Campus area "Cad.dwg" file with the "NCSU campus Orthophoto.SID" image file and produce a final "My Name" .mxd map file using the "Cad.dwg" layers and features for future geoprocessing analysis.


Part One:
1. Save a blank ArcMAP map file to "My_ Name".mxd.
2. The symbology for any layers and features should be edited for ease of use at any time doing the process.
3. Add the "Cad.dwg" file and "Orthophoto.SID" file to the Data Frame
4. Verify and configure the State Plan Coordinate system for the "Orthophoto.SID" layer.
5. Use the Georeferencing Toolbar tools to align the the selected "Cad.dwg" polyline layer to the "Orthophoto.SID" file as accurately as possible (within 20 feet) with the use of at least 2 separate and properly placed control points.

6. Export a World file with the georeferenced coordinates for the "Cad.dwg" file with the Export Raster World File Tool.

Part Two:
1. After analyzing the layers of the "Cad.dwg" file and selecting the necessary features and layers export the selected set of cad features into a new "Geodatabase.gdb" file. It is advised that the Feature Class to Feature Class Tool be used.
2. Analyze the Attribute Tables for the usable features and create the proper layers for a geoprocessing analysis.
3. Verify that all buildings are polygons for future management analysis. If there are any errors, analyze the polyline layer for errors, and then use the Repair Geometry Tool to create closed polylines. Manually edit any polylines which the Repair Geometry Tool cannot fix, and rerun the tool to produce an accurate polyline layer.
4. From the corrected polyline layer create a new building polygon layer using the Feature to Polygon Tool.
5. After selecting, creating, and configuring the necessary layers for the final map, configure a "Geodatabase.gdb" file with only the required features for future geoprocessing analysis.
6. Save this as the final "My_Name" .mxd file.


This exercise became more interesting when the "Cad.dwg" polyline layer would return to its original location after each rescale, seems there were a couple of cad points (possibly xref points) far away from the actual campus drawing which caused this. There were missing building polygons which had to created to obtain an accurate building layer for future geoprocessing analysis. This is a problem with 2D cad files, it is not unusual to find drawing errors which have to edited and repaired before the file can be used. You will also learn that ArcMap does not export out only selected cad layers into a "Geodatabase.gdb" file. In many cases it would be best to analyze and configure the cad file for selected data only before use in ArcMAP.


To verify the accuracy of the georeferencing process, use the Measure Tool to check the distance between the same feature points of the "Cad.dwg" and "Orthophoto.SID" layers from the center to the outer extent of the campus site. The smaller the measurement distances are, especially within the main center area of the campus site, the more accurate your final analysis will be. A second aspect to verify is that all required polygons are showing on the campus site. If not, they will have to be created from the polyline features. Both of these skills require experience to obtain the highest mapping accuracy. After producing a final Geodatabase .gdb file you should open and verify that all final selected data is present and correct.