• Drawing 3D Earth by webgl


    It may be convenient to display the 3D model through three.js, but do you know how it works step by step from mesh construction to mapping to final rendering? Now we can implement it directly by using the underlying web GL and a little mathematical knowledge. The effect of this section:Webgl 3D Earth content syllabus […]

  • Just technology: improve the accuracy of road network estimation based on GPS trajectory


    Road network data is very important for many applications in cities, such as vehicle navigation and route optimization. The traditional road data acquisition method depends on the acquisition vehicle, which consumes a lot of manpower and material resources. With the popularity of GPS equipment, massive trajectory data is generated in cities, so that we can […]

  • Visualization of network drawing with itraph in tecdat | R language


    Link to the original text:http://tecdat.cn/?p=22886 This article assumes that you already know how to build a basic network diagram using the iGraph library. Basically, iGraph allows several types of input to be converted into a graphic object, which can be drawn using the plot() function, as shown below. #   Create data network <- graph(data , mode=’undirected’) #   […]

  • Figure (1)


    The concept of graph Related concepts Concept name definition adjacent vertex Two points are connected by an edge power The edge has a corresponding number network Weighted graph degree Degree = out degree + in degree route Vertex sequence path length In non weighted graph is the number of edges on the path, and in […]

  • Implementation of graph storage structure


    adjacency matrix #include <stdio.h> #include <stdlib.h> #include <data.h> #define MAX_ VERTEX_ Num 20 // maximum number of vertices #Define vrtype int // relationship between vertices #Define infotype char // pointer variable to store arc or extra information #Define vertex type int // vertex data type typedef enum{DG,DN,UDG,UDN}GraphKind;// Four types of enumeration graphs Typedef struct // […]

  • Depth first search


    The process of depth first search is similar to the prior traversal of tree First, arbitrarily find a vertex that has not been traversed. For example, starting from V1, because V1 has been visited first, it is necessary to mark V1 as visited; Then traverse the adjacency points of V1, for example, visit V2 and […]

  • breadth-first search


    Breadth first search is similar to hierarchical tree traversal. Starting from a vertex in the graph, when traversing each vertex, all its adjacent points are traversed in turn, and then starting from these adjacent points, their adjacent points are also accessed in turn. Follow this procedure until all the adjacent points of the visited vertices […]

  • JavaScript graphic example: Hilbert curve


    In 1891, German mathematician David Hilbert constructed a kind of curve. First, he divided a square into four small squares, starting from the center of the square in the northwest corner, going south to the center of the square in the southwest, then east to the center of the square in the southeast corner, and […]

  • Understanding topological ordering


    preface Topological sort, also known as topological order, is a bit confusing, because topological sort is not a pure sort algorithm, it is only for the purpose of sortingA class of GraphsTo find a linear order that can be executed. This algorithm sounds like a big one. Today’s interviews are also very popular. For example, […]

  • Application of graph topological ordering and critical path solving


    1. Topological sorting 1.1 introduction to topological sorting There are ⼀ digraphs that represent ⼯ processes, in which ⽤ vertices represent activities, and arcs represent the priority relationship between activities. In this way, digraphs represent ⽹ activities for vertices, which is called activity on vertex networkAs shown in Figure 1.1.1 below:The finite set of activities […]

  • UE4 / Unity: basic elements of map drawing — surface and volume


    preface Drawing map basic element line based on UE4 / Unity (Part 1) Drawing map basic element line based on UE4 / Unity (Part 2) After drawing lines on the map, the next step is to draw faces and volumes As one of the basic elements of map rendering, surface can represent all kinds of […]

  • [grid compression evaluation] meshquan, meshopt, Draco


    catalog introduceKHR_mesh_quantizationandEXT_meshopt_compression Use, usage Performance (compression, loading, parsing) Available (scene, range) shortcoming Guess the future direction of improvement summary introduce Gltf compression, estimates all knowDracoBecause of the adaptation of gltfloader to applets, we found that there are many other compression extensions, such asKHR_mesh_quantizationandEXT_meshopt_compression KHR_mesh_quantization Quantification, also known as vectorization, is to express the data represented […]