Automatic identification of cell files in light microscopic images of conifer wood

International audienceIn this paper, we present an automatic method to recognize cell files in light microscopic images of conifer wood. This original method is decomposed into three steps: the segmentation step which extracts some anatomical structures in the image, the classification step which identifies in these structures the interesting cells, and the cell files recognition step. Some preliminary results obtained on several species of conifers are presented and analyzed

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Automated efficient computation of crown transparency from tree silhouette images

International audienceThe transparency of trees is the most important indicator for a forest health assessment. This paper presents an efficient method for calculating the crown transparency coefficient from tree binary images. This coefficient is based on the automated quantification of the deep indentation, macro-hole and micro-hole densities. Circular structuring elements are introduced, among other things, to automatically find the significant biological size. The symmetric tree convex hull and the tree smoothed contour are defined to delineate the reference areas necessary to evaluate the above-mentioned densities. Statistical thresholds are proposed to eliminate human operator subjectivity, especially in the automated identification of anatomical elements such as soft and deep crown-indentations or macro and micro crown-holes. A point-wise transparency map is produced to better appreciate the origin of the visible skylight areas in the crown. The crown micro-hole density is calculated from the 0.1-to-0.5 transparency points, the crown macro-hole density from the 0.5-to-1 transparency points. We finally opt for weighting of the above three densities with regard to the importance of the symptoms they describe for a more relevant crown transparency coefficient. A comparative study on several trees from full-size and half-size binary images showed that our method is similar overall to the DSO and less sensitive to scale reduction

Automated characterization of the mature root system form by a double-quadrangle-shaped polygon

International audienceWe describe in this paper a new global approach to characterize the geometry of the root system area from black-and-white silhouettes. We introduce a covering polygon composed of two superimposed quadrangles to evaluate geometry features or to classify the growth strategy of root systems: the convex hull of the root system is progressively reduced to a double-quadrangle-shaped polygon by iterative suppression of least significant vertices to only keep the major geometry features. The root system density is addressed by the analysis of the hole distribution. The root system porosity is estimated from the decomposition of background regions in circular elements. An automated repartition of circular elements by 2-means clustering is introduced for a best appreciation of macro- and micro-holes, respectively associated to the anchorage and nutrient recovery potentials. The global parameters of the root system are evaluated from the geometry and density properties of the double-quadrangle-shaped polygon. The experimental studies address the sensitivity of the double-quadrangle-shaped polygon, especially the evaluation of the geometrical stability of the polygon according to slight variations of the root system segmentation. Several experiments, performed using a representative set composed of 100 root system silhouettes of several species - arabidopsis, chick pea, palm tree, rice, sorghum, and wheat - at different stages of growth, underline the robustness of the shape parameters, especially the upper and lower penetration angles

An automated method for tree-ring delineation based on active contours guided by DT-CWT complex coefficients in photographic images: Application to Abies alba wood slice images

International audienceThis paper describes an efficient method for delineating tree-rings and inter tree-rings in wood slice images. The method is based on an active contour approach and a multi-scale gradient map resulting from the Dual Tree Complex Wavelet Transform (DT-CWT). The method is automated and does not require any pith localization. It is also quite robust to some defect structures such as branch prints, cracks, knots or mold. We applied the method to process entire Abies alba wood slices (aged from 10 to 50 years) from bark to pith, which amounted to about 200 tree-rings. Our automatic delineation method performed accurately compared to the manual expert measurements with a mean F-score of 0.91 for the quality of delineation