1:10,000 Base Map Updates

Province of Nova Scotia, Canada

Background
The Province of Nova Scotia is undertaking projects to update and correct the 1600, 1:10,000 provincial base maps. The project included 3 primary objectives:

• Update existing base maps to current status.
• Improve the accuracy and content of the base maps using softcopy photogrammetry.
• Creation of orthomosaics for each map tile.

Project Workflow
During the past 9 years Eastcan has been contracted to update approx. 550 map tiles. Tasks include updates and corrections to the base data and creation of the rectified imagery for each tile. Inputs for the project included scanned aerial photography, AT reports and the existing data sets in ESRI SHP file format.

The supplied raster imagery was used to update and correct the existing vector (SHP) data. The original SHP files were converted to Cardinal Systems’ VR format. The SHP feature codes were maintained in the VR layer names. The VR data was edited by Eastcan’s photogrammetric team. Photogrammetric edits were converted back to SHP format for topology edits by our GIS team.

The updated files underwent a manual and digital inspection. The manual inspection included a second translation back to VR format for a final review by Eastcan’s senior photogrammetrist to ensure all edits were correctly completed and no data was lost or corrupted. The corrected and updated files were then digitally inspected for topology and coding errors. The digital inspection included a review of the slope and connectivity of the features using client supplied QA software. After passing each inspection stage the data was submitted to the client for final review.

Field Edits
The client conducted field inspections of the map updates. The field review provided a detailed classification for roads and buildings. The field data was provided to Eastcan for incorporation in the vector data sets.

Ortho Creation
The final production stage was the creation of orthomosaics for each tile. The scanned imagery was rectified using the updated created DTM and mosaiced into tiles using Inpho Systems’ OrthoVista software. The final deliverable for the project was a GeoTIF file for each tile and an orthophoto seam file (in SHP format) for the entire project area.