67 O ne of the main functions of graphic displays is drawing straight lines. To draw lines quickly, the speed of the applied algorithm is critical. The following three different approaches exist: I discrete differential analysis (DDA), introduced by Bresenham, 1 I combinatory analysis, 2 and I linguistic methods. 3,4 The most famous approach remains the DDA, since extended by N-step algorithms....

Contouring remains a major application of computer graphics. Contours are typically modelled, rst as conic sections, and then as straight-line approximations to the conics. In this paper, it is shown how the accuracy of this straight-line approximation can be indicated. In addition, a reenement is proposed that yields a better straight-line approximation without major cost overhead.

Cutting straight line transects through dense forest is time consuming and expensive when large areas need to be surveyed for rare or highly clustered species. We argue that existing paths or game trails may be suitable as transects for line transect sampling even though they will not, in general, run straight. Formulas and software currently used to estimate local density using perpendicular d...

A high-speed method for line detection is proposed in this paper. By shifting the black points in a black/white image 1, a parallel line for each straight line on I will be generated. Through the use of the geometric property on a pair of parallel lines, the parameter sets of those lines possibly on I can be obtained immediately. Since the transform from image space to parameter space is one to...

An “adaptive” variant of Ruppert’s Algorithm for producing quality triangular planar meshes is introduced. The algorithm terminates for arbitrary Planar Straight Line Graph (PSLG) input. The algorithm outputs a Delaunay mesh where no triangle has minimum angle smaller than 26.45◦ except “across” from small angles of the input. No angle of the output mesh is smaller than arctan [(sin θ∗)/(2 − co...

An orthogonal network for a given set of n points in the plane is an axis-aligned planar straight line graph that connects all input points. We show that for any set of n points in the plane, there is an orthogonal network that (i) is short having a total edge length of O(jT j), where jT j denotes the length of a minimum Euclidean spanning tree for the point set; (ii) is small having O(n) verti...

An advanced edge-based method of feature detection and extraction is developed for object description in digital images. It is useful for the comparison of different images of the same scene in aerial imagery, for describing and recognizing categories, for automatic building extraction and for finding the mutual regions in image matching. The method includes directional filtering and searching ...

(1) Each pair of points can be joined by one and only one straight line segment. (2) Any straight line segment can be indefinitely extended in either direction. (3) There is exactly one circle of any given radius with any given center. (4) All right angles are congruent to one another. (5) If a straight line falling on two straight lines makes the interior angles on the same side less than two ...

In this report we study the effect of an optimizing algorithm for straight–line code which first constructs a directed acyclic graph representing the given program and then generates code from it. We show that this algorithm produces optimal code with respect to the classical transformations such as Constant Folding, Common Subexpression Elimination, and Dead Code Elimination. In contrast to th...

In this paper we present a formalism for the formation of self consistent, hierarchical, "Low-Level" groupings of pairs of straight line segments from which all higher level groupings may be derived. Additionally, each low-level grouping is associated with a "Quality" factor, based on evidential reasoning, which reflects how much the groupings differ from mathematically perfect ones. This forma...