PCL 点云转深度图
什么是深度图
深度图像（depth image）也被称为距离影像（range image），是指将从图像采集器（相机或雷达）到场景中各点的距离（深度）作为像素值的图像，它直接反映了景物可见表面的几何形状。深度图像经过坐标转换可以计算为点云数据，有规则及必要信息的点云数据也可以反算为深度图像数据。
深度数据流所提供的图像帧中，每一个像素点代表的是在深度感应器的视野中，该特定的（x, y）坐标处物体到离摄像头平面最近的物体到该平面的距离（以毫米为单位）。
#include <pcl/range_image/range_image.h> //深度图像的头文件
int main(int argc, char** argv)
{
pcl::PointCloud<pcl::PointXYZ> pointCloud; //定义点云的对象
// 循环产生点云的数据
for (float y = -0.5f; y <= 0.5f; y += 0.01f) {
for (float z = -0.5f; z <= 0.5f; z += 0.01f) {
pcl::PointXYZ point;
point.x = 2.0f - y;
point.y = y;
point.z = z;
pointCloud.points.push_back(point); //循环添加点数据到点云对象
}
}
pointCloud.width = (uint32_t)pointCloud.points.size();
pointCloud.height = 1; //设置点云对象的头信息
//实现一个呈矩形形状的点云
// We now want to create a range image from the above point cloud, with a 1deg angular resolution
//angular_resolution为模拟的深度传感器的角度分辨率，即深度图像中一个像素对应的角度大小
float angularResolution = (float)(1.0f * (M_PI / 180.0f)); // 1.0 degree in radians
//max_angle_width为模拟的深度传感器的水平最大采样角度，
float maxAngleWidth = (float)(360.0f * (M_PI / 180.0f)); // 360.0 degree in radians
//max_angle_height为模拟传感器的垂直方向最大采样角度 都转为弧度
float maxAngleHeight = (float)(180.0f * (M_PI / 180.0f)); // 180.0 degree in radians
//传感器的采集位置
Eigen::Affine3f sensorPose = (Eigen::Affine3f)Eigen::Translation3f(0.0f, 0.0f, 0.0f);
//深度图像遵循坐标系统
pcl::RangeImage::CoordinateFrame coordinate_frame = pcl::RangeImage::CAMERA_FRAME;
float noiseLevel = 0.0f; //noise_level获取深度图像深度时，近邻点对查询点距离值的影响水平
float minRange = 0.0f; //min_range设置最小的获取距离，小于最小获取距离的位置为传感器的盲区
int borderSize = 1; //border_size获得深度图像的边缘的宽度
pcl::RangeImage rangeImage;
rangeImage.createFromPointCloud(pointCloud,
angularResolution,
maxAngleWidth,
maxAngleHeight,
sensorPose,
coordinate_frame,
noiseLevel,
minRange,
borderSize);
std::cout << rangeImage << "\n";
}
API 说明
createFromPointCloud [1/2]
Create the depth image from a point cloud。
template<typename PointCloudType >
void pcl::RangeImage::createFromPointCloud(const PointCloudType & point_cloud,
float angular_resolution = pcl::deg2rad(0.5f),
float max_angle_width = pcl::deg2rad(360.0f),
float max_angle_height = pcl::deg2rad(180.0f),
const Eigen::Affine3f &sensor_pose = Eigen::Affine3f::Identity(),
RangeImage::CoordinateFrame coordinate_frame = CAMERA_FRAME,
float noise_level = 0.0f,
float min_range = 0.0f,
int border_size = 0);
共有 9 个参数，如下表所示：
| 参数 | 描述 |
|---|---|
| point_cloud | the input point cloud |
| angular_resolution | the angular difference (in radians) between the individual pixels in the image |
| max_angle_width | an angle (in radians) defining the horizontal bounds of the sensor |
| max_angle_height | an angle (in radians) defining the vertical bounds of the sensor |
| sensor_pose | an affine matrix defining the pose of the sensor (defaults to Eigen::Affine3f::Identity () ) |
| coordinate_frame | the coordinate frame (defaults to CAMERA_FRAME) |
| noise_level | - The distance in meters inside of which the z-buffer will not use the minimum, but the mean of the points. If 0.0 it is equivalent to a normal z-buffer and will always take the minimum per cell. |
| min_range | the minimum visible range (defaults to 0) |
| border_size | the border size (defaults to 0). Set to std::numeric_limits<int>::min() to turn cropping off. |
createFromPointCloud [2/2]
Create the depth image from a point cloud.
template<typename PointCloudType >
void pcl::RangeImage::createFromPointCloud(const PointCloudType &point_cloud,
float angular_resolution_x = pcl::deg2rad(0.5f),
float angular_resolution_y = pcl::deg2rad(0.5f),
float max_angle_width = pcl::deg2rad(360.0f),
float max_angle_height = pcl::deg2rad(180.0f),
const Eigen::Affine3f &sensor_pose = Eigen::Affine3f::Identity(),
RangeImage::CoordinateFrame coordinate_frame = CAMERA_FRAME,
float noise_level = 0.0f,
float min_range = 0.0f,
int border_size = 0);
共有 10 个参数，如下表所示：
| 参数 | 描述 |
|---|---|
| point_cloud | the input point cloud |
| angular_resolution_x | the angular difference (in radians) between the individual pixels in the image in the x-direction |
| angular_resolution_y | the angular difference (in radians) between the individual pixels in the image in the y-direction |
| max_angle_width | an angle (in radians) defining the horizontal bounds of the sensor |
| max_angle_height | an angle (in radians) defining the vertical bounds of the sensor |
| sensor_pose | an affine matrix defining the pose of the sensor (defaults to Eigen::Affine3f::Identity () ) |
| coordinate_frame | the coordinate frame (defaults to CAMERA_FRAME) |
| noise_level | - The distance in meters inside of which the z-buffer will not use the minimum, but the mean of the points. If 0.0 it is equivalent to a normal z-buffer and will always take the minimum per cell. |
| min_range | the minimum visible range (defaults to 0) |
| border_size | the border size (defaults to 0). Set to std::numeric_limits<int>::min() to turn cropping off. |
createFromPointCloud 实现
template <typename PointCloudType> void
RangeImage::createFromPointCloud (const PointCloudType& point_cloud,
float angular_resolution_x, float angular_resolution_y,
float max_angle_width, float max_angle_height,
const Eigen::Affine3f& sensor_pose, RangeImage::CoordinateFrame coordinate_frame,
float noise_level, float min_range, int border_size)
{
setAngularResolution (angular_resolution_x, angular_resolution_y);
width = static_cast<std::uint32_t> (pcl_lrint (std::floor (max_angle_width*angular_resolution_x_reciprocal_)));
height = static_cast<std::uint32_t> (pcl_lrint (std::floor (max_angle_height*angular_resolution_y_reciprocal_)));
int full_width = static_cast<int> (pcl_lrint (std::floor (pcl::deg2rad (360.0f)*angular_resolution_x_reciprocal_))),
full_height = static_cast<int> (pcl_lrint (std::floor (pcl::deg2rad (180.0f)*angular_resolution_y_reciprocal_)));
image_offset_x_ = (full_width -static_cast<int> (width) )/2;
image_offset_y_ = (full_height-static_cast<int> (height))/2;
is_dense = false;
getCoordinateFrameTransformation (coordinate_frame, to_world_system_);
to_world_system_ = sensor_pose * to_world_system_;
to_range_image_system_ = to_world_system_.inverse (Eigen::Isometry);
//std::cout << "to_world_system_ is\n"<<to_world_system_<<"\nand to_range_image_system_ is\n"<<to_range_image_system_<<"\n\n";
unsigned int size = width*height;
points.clear ();
points.resize (size, unobserved_point);
int top=height, right=-1, bottom=-1, left=width;
doZBuffer (point_cloud, noise_level, min_range, top, right, bottom, left);
cropImage (border_size, top, right, bottom, left);
recalculate3DPointPositions ();
}
Debug
createFromPointCloud
doZBuffer
getImagePoint
EIGEN_STRONG_INLINE Matrix