Adaptive Framework for the Delineation of Homogeneous Forest Areas Based on LiDAR Points

New publication about forest area segmentation online.

We propose a flexible framework for automated forest patch delineations that exploits a set of canopy structure features computed from airborne laser scanning (ALS) point clouds. The approach is based on an iterative subdivision of the point cloud using k-means clustering followed by an iterative merging step to tackle oversegmentation. The framework can be adapted for different applications by selecting relevant input features that best measure the intended homogeneity. In our study, the performance of the segmentation framework was tested for the delineation of forest patches with a homogeneous canopy height structure on the one hand and with similar water cycle conditions on the other. For the latter delineation, canopy components that impact interception and evapotranspiration were used, and the delineation was mainly driven by leaf area, tree functional type, and foliage density. The framework was further tested on two scenes covering a variety of forest conditions and topographies. We demonstrate that the delineated patches capture well the spatial distributions of relevant canopy features that are used for defining the homogeneity. The consistencies range from R2=0.84 to R2=0.86 and from R2=0.80 to R2=0.91 for the most relevant features in the delineation of patches with similar height structure and water cycle conditions, respectively.

Bruggisser, M., Hollaus, M., Wang, D., & Pfeifer, N. (2019). Adaptive Framework for the Delineation of Homogeneous Forest Areas Based on LiDAR Points. Remote Sensing, 11(2), 189

Singel Tree Detection and Modelling Tree Architecture

Processing of the LiDAR-UAV point clouds for tree parametrisation continued. After single tree detection followed by stem extraction the 3D tree architecture models are derivable for area-wide data sets. This will be the basis for further analysis of forest moisture conditions on detailed scale.

 

 

 

 

Bremer, M., Wichmann, V. & Rutzinger, M. (2018): Multi-temporal fine-scale modelling of Larix decidua forest plots using terrestrial LiDAR and hemispherical photographs. Remote Sensing of Environment. Vol. 206, pp. 189–204.

First results from LiDAR UAV acquisition available

In spring 2018 the first LiDAR UAV acquisition has been conducted with the Riegl RiCOPTER VUX-1LR. Thirteen strips were flown for a 4D-FORMAT test plot in Fürstenfeld (Austria) resulting in point densities ranging from 8.000 to 20.000 pts/m² including multi echoes. Figures below show flight preparation, conduction, intensity coloured and RGB coloured point cloud respectively.

 

  

  

Ongoing Ground Truth Measurments

During the snow free period the 4D-FORMAT team conducts ground truth measurements of soil moisture, which are collected simultaneously during Sentinel-1 overflights. The test areas for probing comprise selected forest types and open agricultural land for calibration.

The Alps from Space Workshop

The 4D-FORMAT team presents initial results about automated tree species mapping at the Earth Observation for Alps (eo4alps) workshop held from 27-29th of June 2018 in Innsbruck Austria and organised by ESA. The abstract is available here.

 

Kollert, A., Rutzinger, M., Bremer, M., Hollaus, M., Pfeifer, N., Bruggisser, M., Bauer-Marschallinger, B., Hagen, K., Schadauer, K., Gartner, K. & Bauerhansl, C. (2018): Mapping Tree Species in Complex Terrain Based on Sentinel-2 Time Series. In: eo4alps. Innsbruck, Austria.

 

 

 

Kick-off Meeting

The 4D-FORMAT consortium consisting of the Austrian Academy of Sciences, the Austrian Research Centre for Forests, and the TU Wien met in July for the project kick-off meeting in Vienna presenting the planned tasks and first work in progress. In the afternoon the 4D-FORMAT consortium visited selected test sites in the Vienna Woods, their instrumentation, and discussed the potential in-situ data sampling strategies.

 

4D-FORMAT granted by Austrian Space Applications Programm

The project 4D FORest moisture MApping Based on multi-Temporal earth observation signatures has been granted by the Austrian Space Applications Programm (ASAP) of the Austrian Research Promotion Agency (FFG).  The aim of the 2.5 year project 4D-FORMAT is to develop an area-wide applicable mapping product for forest soil moisture conditions considering species compositions. The mapping products will combine microwave remote sensing data (Sentinel-1) with multispectral data (Sentinel-2) and will additionally integrate high resolution digital surface models from airborne laser scanning and photogrammetry in order to define homogeneous forest topographic units for multi-temporal analysis. The latter will allow an innovative object-based analysis on homogeneous forest units addressing the forest structure and topography in relation to moisture and species composition.