小编Fin*_*ley的帖子

我从KITTI的部分里程计中获取了校准文件，其中一个校准文件的内容如下：

P0: 7.188560000000e+02 0.000000000000e+00 6.071928000000e+02 0.000000000000e+00 0.000000000000e+00 7.188560000000e+02 1.852157000000e+02 0.000000000000e+00 0.000000000000e+00 0.000000000000e+00 1.000000000000e+00 0.000000000000e+00
P1: 7.188560000000e+02 0.000000000000e+00 6.071928000000e+02 -3.861448000000e+02 0.000000000000e+00 7.188560000000e+02 1.852157000000e+02 0.000000000000e+00 0.000000000000e+00 0.000000000000e+00 1.000000000000e+00 0.000000000000e+00
P2: 7.188560000000e+02 0.000000000000e+00 6.071928000000e+02 4.538225000000e+01 0.000000000000e+00 7.188560000000e+02 1.852157000000e+02 -1.130887000000e-01 0.000000000000e+00 0.000000000000e+00 1.000000000000e+00 3.779761000000e-03
P3: 7.188560000000e+02 0.000000000000e+00 6.071928000000e+02 -3.372877000000e+02 0.000000000000e+00 7.188560000000e+02 1.852157000000e+02 2.369057000000e+00 0.000000000000e+00 0.000000000000e+00 1.000000000000e+00 4.915215000000e-03
Tr: 4.276802385584e-04 -9.999672484946e-01 -8.084491683471e-03 -1.198459927713e-02 -7.210626507497e-03 8.081198471645e-03 -9.999413164504e-01 -5.403984729748e-02 9.999738645903e-01 4.859485810390e-04 -7.206933692422e-03 -2.921968648686e-01

可以看出P0、P1代表黑白相机，P2、P3代表彩色相机。据我了解，相机内在的常见形状是

fx 0  cx
0  fy cy
0  0  1 .

所以我无法弄清楚每一行中剩余的三个参数（我猜用于失真校正）以及 …

我想编译一个开放项目，它需要 Eigen3，我遵循了它的指导方针，但卡在了这一步：

“将环境变量 Eigen3_DIR 设置为 {YOUR_EIGEN3_DIRECTORY}/eigen3/cmake。”

我已经安装了 CMake gui，它在配置后打印了以下错误

Make Error at src/CMakeLists.txt:15 (find_package):
  By not providing "FindEigen3.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Eigen3", but
  CMake did not find one.

  Could not find a package configuration file provided by "Eigen3" with any
  of the following names:

    Eigen3Config.cmake
    eigen3-config.cmake

  Add the installation prefix of "Eigen3" to CMAKE_PREFIX_PATH or set
  "Eigen3_DIR" to a directory containing one of the above files. …

将句柄的句柄设置为指针指针但不是指针的意图是什么？如下代码:

FT_Library library;
FT_Error error = FT_Init_FreeType( &library );

哪里

typedef struct FT_LibraryRec_  *FT_Library

所以&library是一个FT_LIBraryRec_类型的句柄FT_LIBraryRec_**

  unsigned int updateStandardStopping(unsigned int numInliers, unsigned int totPoints, unsigned int sampleSize)
    {
        double max_hypotheses_=85000;
        double n_inliers = 1.0;
        double n_pts = 1.0;
        double conf_threshold_=0.95

        for (unsigned int i = 0; i < sampleSize; ++i)
        {
            n_inliers *= numInliers - i;//n_linliers=I(I-1)...(I-m+1)
            n_pts *= totPoints - i;//totPoints=N(N-1)(N-2)...(N-m+1)
        }
        double prob_good_model = n_inliers/n_pts;

        if ( prob_good_model < std::numeric_limits<double>::epsilon() )
        {
            return max_hypotheses_;
        }
        else if ( 1 - prob_good_model < std::numeric_limits<double>::epsilon() )
        {
            return 1; 
        }
        else 
        {
            double nusample_s = log(1-conf_threshold_)/log(1-prob_good_model);
            return …

对于CUDA，我知道在向默认流（空流）发出启动命令后，它们是异步执行的，那么在OpenCL中呢？示例代码如下：

cl_context context;
cl_device_id device_id;
cl_int err;
...
cl_kernel kernel1;
cl_kernel kernel2;
cl_command_queue Q = clCreateCommandQueue(context, device_id, 0, &err);
...
size_t global_w_offset[3] = {0,0,0};
size_t global_w_size[3] = {16,16,1};
size_t local_w_size[3] = {16,16,1};
err = clEnqueueNDRangeKernel(Q, kernel1, 3, global_w_offset, global_w_size, 
                             local_w_size, 0, nullptr, nullptr);
err = clEnqueueNDRangeKernel(Q, kernel2, 3, global_w_offset, global_w_size, 
                             local_w_size, 0, nullptr, nullptr);
clFinish(Q);

命令排队后是否会kernel1和kernel2异步执行？（即执行重叠）

更新
按照OpenCL的参考，这似乎是一套properties为CL_QUEUE_OUT_OF_ORDER_EXEC_MODE_ENABLE在clCreateCommandQueue能满足我的需要。但是，out_of_order是否意味着异步？

最近遇到了一个C++项目,经常看到以下预编译代码:

#ifdef _WIN32
#define __attribute__(x)
#endif

那么一般来说它用于什么？