---

pcl::PointCloud

• width(int)
  two meanings:

1. it can specify the total number of points in the cloud for unorganized point cloud datasets;
2. it can specify the width (total number of points in a row) of an organized point cloud dataset.

The advantages of an organized dataset is that by knowing the relationship between adjacent points (e.g. pixels), nearest neighbor operations are much more efficient, thus speeding up the computation and lowering the costs of certain algorithms in PCL.

cloud.width = 640; // there are 640 points per line

• height(int)
  two meanings:

1. it can specify the height (total number of rows) of an organized point cloud dataset;
2. it is set to 1 for unorganized datasets (thus used to check whether a dataset is organized or not).

cloud1.width = 640; // Image-like organized structure, with 480 rows and 640 columns,
cloud1.height = 480; // thus 640*480=307200 points total in the dataset

cloud2.width = 307200;
cloud2.height = 1; // unorganized point cloud dataset with 307200 points

• points(std::vector

pcl::PointCloud<pcl::PointXYZ> cloud;
std::vector<pcl::PointXYZ> data = cloud.points;  

• is_dense(bool)
  Specifies if all the data in points is finite (true), or whether the XYZ values of certain points might contain Inf/NaN values (false).
• isOrganized()

if (!cloud.isOrganized ())
// do something

参考

http://www.pointclouds.org/documentation/tutorials/basic_structures.php#basic-structures

---

如何使用pcl库

• CMakeLists.txt

cmake_minimum_required(VERSION 2.6 FATAL_ERROR)
project(MY_GRAND_PROJECT)

find_package(PCL 1.3 REQUIRED COMPONENTS common io)
include_directories(${PCL_INCLUDE_DIRS})
link_directories(${PCL_LIBRARY_DIRS})
add_definitions(${PCL_DEFINITIONS})

add_executable(pcd_write_test pcd_write.cpp)
target_link_libraries(pcd_write_test ${PCL_COMMON_LIBRARIES} ${PCL_IO_LIBRARIES})

We are requesting to find the PCL package at minimum version 1.3. We also says that it is REQUIRED meaning that cmake will fail gracefully if it can’t be found. As PCL is modular one can request:

only one component: find_package(PCL 1.3 REQUIRED COMPONENTS io)
several: find_package(PCL 1.3 REQUIRED COMPONENTS io common)
all existing: find_package(PCL 1.3 REQUIRED)

注：为了方便，用的是全部模块

find_package(PCL 1.7 REQUIRED)

When PCL is found, several related variables are set:

PCL_FOUND: set to 1 if PCL is found, otherwise unset
PCL_INCLUDE_DIRS: set to the paths to PCL installed headers and the dependency headers
PCL_LIBRARIES: set to the file names of the built and installed PCL libraries
PCL_LIBRARY_DIRS: set to the paths to where PCL libraries and 3rd party dependencies reside
PCL_VERSION: the version of the found PCL
PCL_COMPONENTS: lists all available components
PCL_DEFINITIONS: lists the needed preprocessor definitions and compiler flags

• Weird installations
  CMake has a list of default searchable paths where it seeks for FindXXX.cmake or XXXConfig.cmake. If you happen to install in some non obvious repository (let us say in Documents for evils) then you can help cmake find PCLConfig.cmake adding this line:

set(PCL_DIR "/path/to/PCLConfig.cmake")

before this one:

find_package(PCL 1.3 REQUIRED COMPONENTS common io)
  ...

参考

http://www.pointclouds.org/documentation/tutorials/using_pcl_pcl_config.php#using-pcl-pcl-config