orb_slam2编译 ./build_ros.sh出现问题 很久没办法解决 请大家帮个忙谢谢！

Building ROS nodes
mkdir: cannot create directory ‘build’: File exists
CMake Warning (dev) in CMakeLists.txt:
  No project() command is present.  The top-level CMakeLists.txt file must
  contain a literal, direct call to the project() command.  Add a line of
  code such as

    project(ProjectName)

  near the top of the file, but after cmake_minimum_required().

  CMake is pretending there is a "project(Project)" command on the first
  line.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Deprecation Warning at /opt/ros/noetic/share/ros/core/rosbuild/rosbuild.cmake:7 (cmake_policy):
  The OLD behavior for policy CMP0011 will be removed from a future version
  of CMake.

  The cmake-policies(7) manual explains that the OLD behaviors of all
  policies are deprecated and that a policy should be set to OLD only under
  specific short-term circumstances.  Projects should be ported to the NEW
  behavior and not rely on setting a policy to OLD.
Call Stack (most recent call first):
  CMakeLists.txt:2 (include)

CMake Deprecation Warning at /opt/ros/noetic/share/ros/core/rosbuild/rosbuild.cmake:16 (cmake_policy):
  The OLD behavior for policy CMP0002 will be removed from a future version
  of CMake.

  The cmake-policies(7) manual explains that the OLD behaviors of all
  policies are deprecated and that a policy should be set to OLD only under
  specific short-term circumstances.  Projects should be ported to the NEW
  behavior and not rely on setting a policy to OLD.
Call Stack (most recent call first):
  CMakeLists.txt:2 (include)

CMake Deprecation Warning at /opt/ros/noetic/share/ros/core/rosbuild/rosbuild.cmake:18 (cmake_policy):
  The OLD behavior for policy CMP0003 will be removed from a future version
  of CMake.

  The cmake-policies(7) manual explains that the OLD behaviors of all
  policies are deprecated and that a policy should be set to OLD only under
  specific short-term circumstances.  Projects should be ported to the NEW
  behavior and not rely on setting a policy to OLD.
Call Stack (most recent call first):
  CMakeLists.txt:2 (include)

CMake Deprecation Warning at /opt/ros/noetic/share/ros/core/rosbuild/rosbuild.cmake:20 (cmake_policy):
  The OLD behavior for policy CMP0005 will be removed from a future version
  of CMake.

  The cmake-policies(7) manual explains that the OLD behaviors of all
  policies are deprecated and that a policy should be set to OLD only under
  specific short-term circumstances.  Projects should be ported to the NEW
  behavior and not rely on setting a policy to OLD.
Call Stack (most recent call first):
  CMakeLists.txt:2 (include)

CMake Deprecation Warning at /opt/ros/noetic/share/ros/core/rosbuild/rosbuild.cmake:23 (cmake_policy):
  The OLD behavior for policy CMP0011 will be removed from a future version
  of CMake.

  The cmake-policies(7) manual explains that the OLD behaviors of all
  policies are deprecated and that a policy should be set to OLD only under
  specific short-term circumstances.  Projects should be ported to the NEW
  behavior and not rely on setting a policy to OLD.
Call Stack (most recent call first):
  CMakeLists.txt:2 (include)

[rosbuild] Building package ORB_SLAM2
Failed to invoke /opt/ros/noetic/bin/rospack deps-manifests ORB_SLAM2
[rospack] Error: the rosdep view is empty: call 'sudo rosdep init' and 'rosdep update'

CMake Error at /opt/ros/noetic/share/ros/core/rosbuild/public.cmake:129 (message):
  

  Failed to invoke rospack to get compile flags for package 'ORB_SLAM2'.
  Look above for errors from rospack itself.  Aborting.  Please fix the
  broken dependency!

Call Stack (most recent call first):
  /opt/ros/noetic/share/ros/core/rosbuild/public.cmake:207 (rosbuild_invoke_rospack)
  CMakeLists.txt:4 (rosbuild_init)

-- Configuring incomplete, errors occurred!
See also "/home/liuxinze/catkin_ws/src/ORB_SLAM2/Examples/ROS/ORB_SLAM2/build/CMakeFiles/CMakeOutput.log".
make: *** No targets specified and no makefile found.  Stop.
 

你好，我是有问必答小助手。为了技术专家团更好地为您解答问题，烦请您补充下（1）问题背景详情，（2）您想解决的具体问题，（3）问题相关代码图片或者报错信息。便于技术专家团更好地理解问题，并给出解决方案。

您可以点击问题下方的【编辑】，进行补充修改问题。

我也遇到这个问题了，并且修改路径成功了，仍然无法解决这个问题，我用的是ubuntu20.04，请问你解决这个问题了吗？

你好 ，我也遇到了相同问题，请问您是如何解决的

需要安装rosdep(c)，强烈推荐使用鱼香ros一键安装！装好之后update一下就能编译通过啦！

看一下这个：https://www.freesion.com/article/7597639275/

sudo -H pip3 install rosdepc

sudo rosdepc init
rosdepc update