Embedded Files
Problem
NCSU requests assistance in building a geodatabase to benefit the management of campus buildings and facilities. This project processes existing datasets to produce a geodatabase of campus buildings, facilities and other infrastructure necessary for future planning and management.
Analysis Procedures
NCSU provided a CAD dataset of existing features and infrastructure pertinent to the campus and surrounding area. Additional data consisted of an orthophoto of the campus and portions of the surrounding area. The CAD dataset was georeferenced in ArcMap using the orthophoto. The required layers were created using the CAD dataset and converted to the appropriate feature class. The geodatabase was created using the relevant layers.
The CAD dataset and orthophoto were imported into ArcMap. The attribute tables for each layer were reviewed. Additionally, I reviewed all available layers in the CAD dataset. The orthophoto had an unknown coordinate system. Using the Data Frame dialog box, I set the coordinate system to NAD 1983 State Plane North Carolina FIPS 3200 (US Feet). I then proceeded to georeference the CAD drawing to the orthophoto. Using the Georeferencing tool in ArcMap, I set two control points and evaluated the alignment. The alignment could be better, so I set two additional control points and updated the alignment. Using the measure tool, I assessed the final alignment; the alignment is within 17 feet. Using select by attribute, I proceeded to create shapefiles for each of the layers necessary for the geodatabase: streets (campus only), sidewalks (campus only), streams/creeks, lakes/ponds, buildings (campus only; existing and future), and athletic fields. The buildings, athletic field, and lakes/ponds layers were all created as polyline layers due to the limitations of the CAD dataset. I converted these in ArcMap to polygon shapefiles using the Feature to Polygon tool. The remaining layers (streets, sidewalks, and streams/creeks) were left as polyline shapefiles. Using ArcCatalog, I created a geodatabase and added each of the relevant layers as a feature class.
Results
Image displaying orthophoto alignment of study area (Click to enlarge)
Workflow diagram (Click to enlarge)
Application & Reflection
Given its reliance on built structures in the physical environment, georeferencing is a great skillset for ArcMap users encountering problems or projects related to infrastructure. Additionally, knowing how to handle CAD files in ArcMap is particularly useful for ArcMap users who work in or with professionals in city planning, architecture, and engineering. However, other professional ventures would benefit from georeferencing and CAD conversion as well. Suppose a local historical society would like to catalog and map all statues and monuments in their city (or county, or state, etc.). They could obtain a CAD drawing of these structures for the desired scope in area (i.e., city, county, state). Potentially then, this drawing along with an orthophoto of the relevant geographic extent obtained from satellite imaging could be used to georeference the CAD drawing. Depending on the criteria required of the local historical society, the CAD layers could then be converted into shapefiles. For example, perhaps they would like to be able to view the monuments by historical period (e.g., representing particular wars) or by type of monument (e.g., signs, small monuments, large monuments), or other related factors. Ultimately, a geodatabase with all specified layers given specified criteria could be created and maintained for future management.
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