New thesis: 3D data improves forest inventory

Data on the age and size of trees and other vegetation in the terrain, provides us with the information we need to sustainably manage and utilise forests. In her doctoral thesis at Mistra Digital Forest, Ritwika Mukhopadhyay is investigating whether 3D data collected using remote sensing methods can provide us with this knowledge more quickly, more cost-effectively and with greater precision, as compared to existing methods. This would pave the way for forest management that gives greater consideration to the fact that forests are an important carbon sink, a place for biodiversity, and that wood raw material is an important resource.

Hi Ritwika, in November 2024 you defended your dissertation at SLU. What is your PhD thesis about?

– Currently, we rely on field data to build models that describe the forest, and estimate forest growth. In my thesis, I have explored whether we could gradually move away from that, and instead use 3D information from remote sensing data to estimate volume and biomass. Both parameters are important for making these kinds of estimates. The data has been collected using different sensors, such as aerial laser scanning, digital aerial photogrammetry, and synthetic aperture radar. The common denominator being that these sensors generate data that can be used in combination to create detailed 3D models of the forest.

Why is that interesting?

– From a broader perspective, sustainable forest management is based on us knowing how the forest is doing, but also knowing how much wood and organic material is present in a forest area. Based on this information, we can manage forests in a way that recognises that they are an important carbon sink, a place of biodiversity, and that wood is an important resource. As most of us are probably aware, remote sensing methods have become increasingly common. As technology advances new opportunities open up, enabling us to collect more accurate forest information in a more time-efficient way. In addition, data collection can be repeated, enabling us to compare data over time.

What conclusions did you reach?

– In one study in my thesis, I investigate the possibility of supplementing maps based on low-resolution data from the national laser scan, with high-resolution aerial laser data. The results show that just by scanning a few strips using high-resolution, more expensive laser scanning technology, we get updated and more detailed information about the growth of a larger forest area.