We consider the problem of finding equivalent reorderings of a sparse matrix so that the reordered matrix is suitable for parallel Ganssian elimination. The elimination tree structure is used as our parallel model. We show that the reordering scheme by Jess and Kees generates an elimination tree with minimum height among all such trees from the class of equivalent reorderings. A new height-redu...

Metric Access Methods (MAM) are employed to accelerate the processing of similarity queries, such as the range and the k-nearest neighbor queries. Current methods improve the query performance minimizing the number of disk accesses, keeping a constant height of the structures stored on disks (height-balanced trees). The Slim-tree and the M-tree are the most efficient dynamic MAM so far. However...

A stand generation (or initialization) procedure is designed to furnish morphologically plausible model trees for process-based projection. The steps of the initialization are: (i) the generation of the locations of model trees and the tessellation of tree areas; (ii) the sampling of diameters from a target distribution and assignments of those diameters to model-tree locations; (iii) the calcu...

The objectives of this study are to: (1) evaluate accuracy of tree height measurements of manual stereo viewing on a computer display using digital aerial photographs compared with airborne LiDAR height measurements; and (2) develop an empirical model to estimate stand-level aboveground biomass with variables derived from manual stereo viewing on the computer display in a Cambodian tropical sea...

Airborne laser scanning has been used increasingly for extracting and estimating forest parameters. Experiences in Nordic countries and Canada have shown that retrieval of stem volume and mean tree height on a tree or stand level from laser scanner data performs as well as, or better than, photogrammetric methods, and better than other remote sensing methods. The increasing interest in laser da...

Virtually all techniques for tree height determination follow one of two principles: similar triangles or the tangent method. Most people apply the latter approach, which uses the tangents of the angles to the top and bottom and a true horizontal distance to the subject tree. However, few adjust this method for ground slope, tree lean, crown shape, and crown configuration, making errors commonp...

The concepts of ecotopes and forest sites are used to describe the correlative complexes defined by landform, vegetation structure, stand characteristics relationship between soil physiography. Physically heterogeneous landscapes such as karst, which is characterized abundant sinkholes outcrops, exhibit diverse microtopography. Understanding variation in growth trees a topography important for ...