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...of a number of root axes, the root axes can be thought of as numerous connections of truncated cones. A truncated cone has four parameters: radius of the upper (R1) and lower (R2) circles, the height (L), and the direction of root axis [17] (Fig. 4a). The connection of the truncated cones should be followed by two conditions: the forepart of the truncated cone is larger than the posterior; the primary and adventitious root is thicker than lateral roots. When two truncated cones are connected, a gap appears, as showed in Fig.5a, which affects the visualization effects. A polygon grid algorithm [23] was adopted to eliminate these gaps (Fig. 5b). a b Fig. 4. The basic model of root segment L Z R2 Z R 1 Z z Z x Z y Z Fig. 5. Comparison of the effect of truncated cones connection 4.2 Illumination and texture sub-model Roots are embedded in soil and grow in a dark environment, however, root structure can be looked clearly under illumination. The illumination model in the OpenGL library was adopted for simulating the illumination effect. The root surface was drawn by a texture model, which was constructed by using photos of a root at different stages with textures and integrated with the geom...

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...e visual perspective, the use of generalized cylinders to model branches does not allow for precise shaping of branching points; my models could benefit from alternative methods addressing this issue =-=[42, 89, 93]-=-. To validate the space colonization algorithm quantitatively, it would be useful to compare the generated structures with measured plants; such comparisons may also help to set model pa-161 rameters...

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...initely some superimpositions at the divisions of the trunk; however, they have little visual effect on the final rendering of the trunk, and a refinement process can be applied to solve this problem =-=[55]-=-. 32 (a) (b) Fig. 11. 3D trunk model created by the test images shown in Fig. 1. (a) Polygonal mesh of the trunk. (b) Textured 3D trunk model. One example of the created polygonal mesh is illustrated ...

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...m parallel crosssections. Other algorithms do not try to set up a polygonal mesh from non-parallel cross-sections. Instead they connect branching points like described in the approach by Lluch et al. =-=[97]-=-. However, vessel mining approaches in medical datasets often deliver non-parallel cross-sections along a tree-shaped vessel centerline [98]. In addition the centerlines between the branching points a...

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... models directly [5], which is time consuming for tubular objects. A second class of algorithms involves surface tiling from cross-sections and algorithms connecting tubular objects to a single model =-=[6,7,8]-=-. Most of these algorithms have problems representing furcations of higher order correctly, some do not support changing radii along branches. An algorithm related to our can be found in [9], however ...