#ifndef COLOR_RAMP_H
#define COLOR_RAMP_H
class Color_ramp
  typedef std::array<unsigned char, 3> Color;
  typedef std::pair<double, Color> Step;
  std::vector<Step> m_steps;
public:
  Color_ramp()
    m_steps.push_back (std::make_pair (0, Color{ 192, 192, 255}));
    m_steps.push_back (std::make_pair (0.2, Color{ 0, 0, 255}));
    m_steps.push_back (std::make_pair (0.4, Color{ 0, 255, 0}));
    m_steps.push_back (std::make_pair (0.6, Color{ 255, 255, 0}));
    m_steps.push_back (std::make_pair (0.8, Color{ 255, 0, 0}));
    m_steps.push_back (std::make_pair (1.0, Color{ 128, 0, 0}));
  Color get (double value) const
    std::size_t idx = 0;
    while (m_steps[idx+1].first < value)
      ++ idx;
    double v0 = m_steps[idx].first;
    double v1 = m_steps[idx+1].first;
    const Color& c0 = m_steps[idx].second;
    const Color& c1 = m_steps[idx+1].second;
    double ratio = (value - v0) / (v1 - v0);
    Color out;
    for (std::size_t i = 0; i < 3; ++ i)
      out[i] = static_cast<unsigned char>((1 - ratio) * c0[i] + ratio * c1[i]);
    return out;
#endif // COLOR_RAMP_H
				
las是点云数据常见的存储格式，摄影测量和激光雷达数据均采用此格式，点云数据常用来生成等高线，地籍测量，土方量计算等。本文讲解在ArcGIS平台上生成等高线，等高线平滑，并转换为dwg格式供CASS使用。
文章目录一、创建las数据集二、las生成等高线方法1：点云las→不规则三角网tin→栅格→等高线方法2：点云las→栅格→等高线三、等高线格式转换输出
一、创建las数据集
扩展阅读：ArcGIS10.6创建LAS数据集的两种方法并加载点.
```c++
#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/intersections.h>
#include <vector>
#include <iostream>
typedef CGAL::Exact_predicates_exact_constructions_kernel K;
typedef K::Point_3 Point;
typedef K::Triangle_3 Triangle;
int main()
    // 输入两组点云数据
    std::vector<Point> points1 = {Point(, , ), Point(1, , ), Point(, 1, )};
    std::vector<Point> points2 = {Point(.5, .5, ), Point(1.5, .5, ), Point(.5, 1.5, )};
    // 构造三角形
    Triangle tri1(points1[], points1[1], points1[2]);
    Triangle tri2(points2[], points2[1], points2[2]);
    // 计算交集
    auto result = CGAL::intersection(tri1, tri2);
    if (result) {
        // 如果有交集，输出交集面积
        std::cout << "交集面积为：" << result->area() << std::endl;
    } else {
        std::cout << "两者没有交集" << std::endl;
    return ;
这个代码使用了 CGAL 的精确计算库，可以保证计算结果的精度。