Photograph method to estimate canopy structure parameters of isolated tree-assessment from 3D digitised plants - Thèses Université Clermont Auvergne Accéder directement au contenu
Thèse Année : 2006

Photograph method to estimate canopy structure parameters of isolated tree-assessment from 3D digitised plants

Méthode photographique d'estimation de la structure géométrique d'arbres évaluation sur des plantes digitalisées en 3D

Résumé

A photograph method for estimation of canopy structure has been developed. The method works from a set of digital photographs of a tree (e.g., eight images taken from N, S, E, W, NE, NW, SE and SW). Photographs must be taken so that image processing allows classifying pixels as vegetation or background. Each photograph must involve associated geometrical parameters, namely the distance between the camera and the tree trunk, camera height, camera elevation, camera azimuth around the tree and focal length. The method included estimation of canopy dimension, volume, total leaf area and spatial distribution of leaf area. Canopy height and diameter are estimated on each image from topmost, rightmost and leftmost vegetated pixel location. Canopy dimension is then used to reconstruct the bounding box from a set of voxels. Vegetated pixels in the photographs are used to investigate a series of vegetated voxel using Ray/Box intersection algorithms (Glassner, 1989). Estimation of total leaf area is based on inversion of gap fraction. Two models of inversion are included, Beer=s and binomial model. Spatial distribution of leaf area is estimated by nonlinear least square optimization technique using algorithm L-BFGS-B (Byrd et al. 1995). The method has been implemented using Tree Analyser software written in C++. The method was tested from 3D digitised plants. The latter were used to directly estimate canopy structure and generate virtual perspective photographs with POV-Ray® version 3.5 (Persistence of Vision Development Team). The locations and view angles of the camera were manually controlled by input parameters. The tests were performed on 5 plant species (walnut, peach, mango, olive and rubber). Satisfactory results between measured data and values inferred from the photograph method were found. The effect of voxel size, size of picture discretisation, location of camera and number of pictures was also examined. This work provides a fast and non-destructive method to follow growth and development of isolated tree canopies.
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Dates et versions

tel-02822472 , version 1 (06-06-2020)

Identifiants

  • HAL Id : tel-02822472 , version 1
  • PRODINRA : 16311

Citer

Jessada Phattaralerphong. Photograph method to estimate canopy structure parameters of isolated tree-assessment from 3D digitised plants. Life Sciences [q-bio]. Université Blaise Pascal (Clermont Ferrand 2); Kasetsart University [Siracha Campus], 2006. English. ⟨NNT : ⟩. ⟨tel-02822472⟩
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