3D Model of the NSCC Waterfront Campus
Objective
The case study objective was to generate both a 2D and 3D map of the NSCC Waterfront Campus in Dartmouth, Nova Scotia including the primary building and surrounding landscaping.
Photo Acquisition
Photos were collected in the fall with a 10MP Canon EOS 40D and 50mm lens from a Cessna 172 at an altitude of approximately 1000ft and speed of 140-160 knots. From this altitude, an average ground resolution for the image pixels of approximately 25cm was achieved. A total of nearly 200 photographs were captured during the 45 minute flight six of which were oriented and utilized for digitizing.
GCP Collection
A total of 44 control points were collected throughout the area using a Trimble GeoXT the following afternoon (taking about 4.5 hours). About a dozen of the GPS points were used for photograph orientation with the remaining used for data verification.
Feature Collection
Six photographs were selected from the ones acquired over the campus and were georeferenced within ObliqueMapper. For this case study, emphasis was placed on the level of detail that could be derived from the photographs rather than the amount of time required for digitizing. As such, care was given to capturing the finer details of building overhangs, bridges, ramps, curbs, etc. In total, 205 point features, 172 polygon features and 183 line features were collected.
Results
Although a large amount of time was spent on digitizing, 55 hours in total, the resulting 3D model demonstrates ObliqueMapper's ability to capture fine details, such as cross-walk lines, that would be difficult or impossible to acquire via standard GPS methods.
