Sun Life Building
Client / Collaborator
DMA Architectes
Sector
Architecture, Patrimoine
Location
Montreal
Services
Relevé LiDAR, Relevé par drone, Photogrammetrie
Mandate
The Sun Life Building, an iconic landmark of downtown Montreal, was the subject of a detailed façade analysis mandate. The objective was to document the building's current state to better understand the conditions of the masonry, the conditions of the metal flashings, and the building's overall geometry. This information was used to produce a 3D reproduction of the building and its details, while also producing orthoimages.
The DGTL team carried out a digital survey of the façades, enabling the creation of a point cloud. The scope of work also included capturing the building's roof, ensuring complete coverage of the envelope.
To learn more about the Sun Life Building's history, consult this link
Mandate
The Sun Life Building, an iconic landmark of downtown Montreal, was the subject of a detailed façade analysis mandate. The objective was to document the building's current state to better understand the conditions of the masonry, the conditions of the metal flashings, and the building's overall geometry. This information was used to produce a 3D reproduction of the building and its details, while also producing orthoimages.
The DGTL team carried out a digital survey of the façades, enabling the creation of a point cloud. The scope of work also included capturing the building's roof, ensuring complete coverage of the envelope.
To learn more about the Sun Life Building's history, consult this link
Proposition
GNSS georeferencing and control network
To anchor the project withing a precise coordinate system, control points were georeferenced using a high-precision GNSS system. These points provide a stable reference for all data acquisitions and ensure accurate positioning of the collected dataset. This approach also facilitates the integration of multiple technologies, including terrestrial LiDAR and drone-based photogrammetry.
A survey control network is then established to provide a stable geometric base and minimize positional drift during data acquisition. Strategically distributed across façades, balconies, guardrails, parapets, and neighbouring buildings, more than 100 control points were installed and tied into the GNSS network. This approach achieved a control network with an accuracy of 4 mm over a distance of 150 m.
Terrestrial LiDAR Survey
A terrestrial LiDAR survey was conducted on portions of the building envelope to capture the intricate details of the historic façades, openings, and architectural features. This process provided an accurate record of the existing conditions while preserving the building's rich geometric detail.
All scan stations were registered and adjusted to the survey control network to ensure consistency, precision, and overall accuracy across the entire project.
Drone Survey
A drone-based photogrammetric survey, performed using a high-resolution camera, documented hard-to-reach areas and provided complete coverage of the building. Over the course of multiple flight missions, more than 25,000 images were captured from a variety of angles, resulting in a highly detailed digital reconstruction of the building, including its highest architectural elements.
This approach overcomes the long-range limitations of terrestrial LiDAR by producing dense, high-resolution point clouds for areas that are otherwise difficult to capture.
All collected data was referenced to the primary survey control network, ensuring a detailed, consistent, and fully usable 3D reconstruction.
LiDAR and photogrammetric hybrid
For selected portions of the building, terrestrial LiDAR data and drone photogrammetry were combined to produce a complete, highly detailed, and accurate point cloud. This hybrid approach compensates for the inherent limitations of terrestrial LiDAR while ensuring optimal coverage and comprehensive documentation of the building.
Deliverables
Colorized point cloud
A high-density colorized point cloud is produced, generated from terrestrial LiDAR and photogrammetric data. Constrained by a survey control network, it provides a precise and reliable measurement base for analysis, inspections and all other future interventions. This format is particularly effective for the 3D documentation of heritage buildings.
Orthophotos
Façade orthophotos with a resolution of 2mm per pixel accompany the survey and help visualize cracks, defects, mortar joints and stone details.
Quality Report
Upon completion of the project, a 25-page quality report is produced to document the entire workflow.
The report outlines the methodologies and technologies used throughout the project, including the georeferencing process, the establishment of the survey control network, scanning methodologies, and the evaluation of the results. It also includes photographs taken during the survey, target positioning tables, and observations regarding weather conditions during data acquisition.
