An architect in Hong Kong says laser scanning of Paris' famous Notre Dame Cathedral, carried out by late art historian Andrew Tallon, played a crucial role in the restoration of the Gothic gem.

The more than 850-year-old cathedral has finally reopened its doors after it was partially destroyed by a fire in 2019.

Most of the timber roof and the structure's spire were ravaged by the flames.

Yu Ka-sing, Associate Professor of Practice at the Faculty of Architecture from the University of Hong Kong told RTHK that Tallon's scans of the interior and exterior of the cathedral conducted before the blaze provided basic information for the restoration team to start with.

"Basically, it is the process that can allow the site to create a digital twin of the historic building by collecting a range of geospatial information," he said.

Yu noted that the Emperor Qinshihuang's Mausoleum Site Museum in China cooperated with France on the restoration, and its deputy director Zhou Ping paid a visit to France earlier this year to gain a better understanding of the restoration process.

"In the international heritage conservation aspect, both France and China are of the highest levels," said Yu.

"And also given the fact that the Emperor Qinshihuang's Mausoleum [Site Museum] has also got many burned timber debris, so sharing some similarity with Notre Dame, the two sites have some good knowledge for exchange."

Despite rolling out the red carpet to the public, the 700-million euro restoration project has yet to be completed.

Tasks, such as the restoration of the chevet and sacristy, as well as the installation of stained glass windows will continue.