在ROS-Navigation中有map_server的工具可以把2D SLAM的地图保存为pgm格式，但map_server只是工具，没办法很个性化自由的处理，这里介绍下源代码的形式：

map_server.cpp

#include <ros/ros.h>
#include <nav_msgs/OccupancyGrid.h>
#include <fstream>
#include <iostream>void saveMapCallback(const nav_msgs::OccupancyGrid::ConstPtr& map)
{// 获取地图数据int width = map->info.width;int height = map->info.height;const std::vector<int8_t>& data = map->data;// 创建PGM文件std::ofstream file("/home/user/Desktop/map.pgm");if (!file){ROS_ERROR("Failed to create PGM file");return;}// 写入PGM文件头信息file << "P5" << std::endl;file << width << " " << height << std::endl;file << "255" << std::endl;// 写入地图数据for (const auto& pixel : data){if (pixel == 0){file.put(255);  // 未知区域（白色）}else if (pixel == 100){file.put(0);    // 障碍物（黑色）}else{file.put(205);  // 可行区域（灰色）}}file.close();ROS_INFO("Map saved as map.pgm");
}int main(int argc, char** argv)
{ros::init(argc, argv, "map_saver_example");ros::NodeHandle nh;// 订阅/map话题来获取地图数据ros::Subscriber sub = nh.subscribe("/map", 1, saveMapCallback);ros::spin();return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.0.2)
project(self_map_server)## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTSmap_servernav_msgsroscpprospy
)## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()################################################
## Declare ROS messages, services and actions ##
################################################## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)## Generate messages in the 'msg' folder
# add_message_files(
#   FILES
#   Message1.msg
#   Message2.msg
# )## Generate services in the 'srv' folder
# add_service_files(
#   FILES
#   Service1.srv
#   Service2.srv
# )## Generate actions in the 'action' folder
# add_action_files(
#   FILES
#   Action1.action
#   Action2.action
# )## Generate added messages and services with any dependencies listed here
# generate_messages(
#   DEPENDENCIES
#   nav_msgs
# )################################################
## Declare ROS dynamic reconfigure parameters ##
################################################## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed## Generate dynamic reconfigure parameters in the 'cfg' folder
# generate_dynamic_reconfigure_options(
#   cfg/DynReconf1.cfg
#   cfg/DynReconf2.cfg
# )###################################
## catkin specific configuration ##
###################################
## The catkin_package macro generates cmake config files for your package
## Declare things to be passed to dependent projects
## INCLUDE_DIRS: uncomment this if your package contains header files
## LIBRARIES: libraries you create in this project that dependent projects also need
## CATKIN_DEPENDS: catkin_packages dependent projects also need
## DEPENDS: system dependencies of this project that dependent projects also need
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES self_map_server
#  CATKIN_DEPENDS map_server nav_msgs roscpp rospy
#  DEPENDS system_lib
)###########
## Build ##
############# Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include${catkin_INCLUDE_DIRS}
)## Declare a C++ library
# add_library(${PROJECT_NAME}
#   src/${PROJECT_NAME}/self_map_server.cpp
# )## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
# add_executable(${PROJECT_NAME}_node src/self_map_server_node.cpp)## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})## Specify libraries to link a library or executable target against
# target_link_libraries(${PROJECT_NAME}_node
#   ${catkin_LIBRARIES}
# )
add_executable(self_map_server src/map_server.cpp)
target_link_libraries(self_map_server ${catkin_LIBRARIES})#############
## Install ##
############## all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# catkin_install_python(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )#############
## Testing ##
############### Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_self_map_server.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()## Add folders to be run by python nosetests
# catkin_add_nosetests(test)

package.xml

<?xml version="1.0"?>
<package format="2"><name>self_map_server</name><version>0.0.0</version><description>The self_map_server package</description><!-- One maintainer tag required, multiple allowed, one person per tag --><!-- Example:  --><!-- <maintainer email="jane.doe@example.com">Jane Doe</maintainer> --><maintainer email="user@todo.todo">user</maintainer><!-- One license tag required, multiple allowed, one license per tag --><!-- Commonly used license strings: --><!--   BSD, MIT, Boost Software License, GPLv2, GPLv3, LGPLv2.1, LGPLv3 --><license>TODO</license><!-- Url tags are optional, but multiple are allowed, one per tag --><!-- Optional attribute type can be: website, bugtracker, or repository --><!-- Example: --><!-- <url type="website">http://wiki.ros.org/self_map_server</url> --><!-- Author tags are optional, multiple are allowed, one per tag --><!-- Authors do not have to be maintainers, but could be --><!-- Example: --><!-- <author email="jane.doe@example.com">Jane Doe</author> --><!-- The *depend tags are used to specify dependencies --><!-- Dependencies can be catkin packages or system dependencies --><!-- Examples: --><!-- Use depend as a shortcut for packages that are both build and exec dependencies --><!--   <depend>roscpp</depend> --><!--   Note that this is equivalent to the following: --><!--   <build_depend>roscpp</build_depend> --><!--   <exec_depend>roscpp</exec_depend> --><!-- Use build_depend for packages you need at compile time: --><!--   <build_depend>message_generation</build_depend> --><!-- Use build_export_depend for packages you need in order to build against this package: --><!--   <build_export_depend>message_generation</build_export_depend> --><!-- Use buildtool_depend for build tool packages: --><!--   <buildtool_depend>catkin</buildtool_depend> --><!-- Use exec_depend for packages you need at runtime: --><!--   <exec_depend>message_runtime</exec_depend> --><!-- Use test_depend for packages you need only for testing: --><!--   <test_depend>gtest</test_depend> --><!-- Use doc_depend for packages you need only for building documentation: --><!--   <doc_depend>doxygen</doc_depend> --><buildtool_depend>catkin</buildtool_depend><build_depend>map_server</build_depend><build_depend>nav_msgs</build_depend><build_depend>roscpp</build_depend><build_depend>rospy</build_depend><build_export_depend>map_server</build_export_depend><build_export_depend>nav_msgs</build_export_depend><build_export_depend>roscpp</build_export_depend><build_export_depend>rospy</build_export_depend><exec_depend>map_server</exec_depend><exec_depend>nav_msgs</exec_depend><exec_depend>roscpp</exec_depend><exec_depend>rospy</exec_depend><!-- The export tag contains other, unspecified, tags --><export><!-- Other tools can request additional information be placed here --></export>
</package>