Peterborough Victoria Northumberland & Clarington Catholic School Board

As-Built CAD Roof Plans and Topographic Site Maps

2018 - Building and Infrastucture Renovations
  • ◉ 6 Acre property survey
  • ◉ Unmanned Aerial System used to acquire relative data and point cloud generation
  • ◉ Ground control points (GCP) taken on site with Trimble R2 survey ground unit.
  • ◉ AutoCAD drawings created by information extracted from point clouds.


This school resides at the top of a multi-sloped ridge, causing issues with the outdated septic beds. We were asked to perform a site survey and provide the findings to the chosen engineering firm to allow them to make informed decisions. A completed as-built roof plan has been included in this package for future re-roofing projects.

Instead of surveying the entire site on the ground, our Unmanned Aerial System (UAS) extracts the overall site images tagged with GIS, which are then used to create the point cloud model and overhead orthomosaic maps.

These pointclouds have a very high relative accuracy, but for the information to have a higher absolute accuracy, we need to take this a step further and collect Ground Control Points (GCP) using our ground station unit.

Since we are combining the drone data and the GCPs, far less have to be taken than if this property was surveyed completely on foot. These GCPs are inputted into the model which brings the absolute accuracy to 25cm.

Now that our point cloud model has the desired accuracy, we now extract the necessary information to complete the topography maps and roof plans in AutoCAD software.