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查看两个目录的结构

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$ tree test_a/ test_b/
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test_a/
└── test.txt
test_b/
├── test_b.txt
└── test.txt

使用 diff 逐行比较

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$ diff -aur test_a/ test_b/
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Only in test_b/: test_b.txt
diff -aur test_a/test.txt test_b/test.txt
--- test_a/test.txt	2024-04-01 19:29:35.024777745 +0800
+++ test_b/test.txt	2024-04-01 19:36:22.759553212 +0800
@@ -1 +1 @@
-test_a
+test_b
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使用 pcl-tools 1.12.1 显示点云后出现 segmentation fault

image-1

使用 libpcl-dev-1.12.1 显示点云后显示一大串关于 vtk 的警告且最后出现 sgmentation fault

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2024-03-27 07:06:36.626 (   1.903s) [        1B11AC80]vtkOpenGLPolyDataMapper:328   WARN| vtkOpenGLPolyDataMapper::SetGeometryShaderCode was deprecated for VTK 9.0 and will be removed in a future version.  Use vtkOpenGLShaderProperty::SetGeometryShaderCode instead.
2024-03-27 07:06:36.626 (   1.903s) [        1B11AC80]vtkOpenGLPolyDataMapper:321   WARN| vtkOpenGLPolyDataMapper::GetFragmentShaderCode was deprecated for VTK 9.0 and will be removed in a future version.  Use vtkOpenGLShaderProperty::GetFragmentShaderCode instead.
2024-03-27 07:06:36.626 (   1.903s) [        1B11AC80]vtkOpenGLPolyDataMapper:313   WARN| vtkOpenGLPolyDataMapper::SetFragmentShaderCode was deprecated for VTK 9.0 and will be removed in a future version.  Use vtkOpenGLShaderProperty::SetFragmentShaderCode instead.
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安装 Git

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sudo apt install git
git config --global user.name "Your Name"
git config --global user.email "youremail@domain.com"

配置防火墙

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sudo apt install ufw
sudo ufw allow "OpenSSH"
sudo ufw enable
sudo ufw allow http
sudo ufw allow https
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点云的表示方式

pcl里的点云多种表示方式：

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// const
ConstCloudIterator<PointT> cloud_iterator;

pcl::PointCloud<PointT> cloud;

// with indices
pcl::PointCloud<PointT> cloud;
std::vector<int> indices;

// with indices
pcl::PointCloud<PointT> cloud;
pcl::PointIndices indices;
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高通滤波: 通常使用来检测边缘

常见算子

sobel算子

math-1

Scharr算子 (更敏感/细致)

math-2

Laplacian(拉普拉斯)算子 (对噪声较敏感，一般搭配其他操作)

math-3

具体代码例子

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import matplotlib.pyplot as plt
import matplotlib.image as mpimg

import cv2
import numpy as np

%matplotlib inline

# Read in the image
image = cv2.imread('images/curved_lane.jpg')
image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)

gray = cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)

f, (p1, p2) = plt.subplots(1, 2, figsize=(20,10))
p1.set_title('original img')
p1.imshow(image)

p2.set_title('gray img')
p2.imshow(gray, cmap='gray')
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低通滤波: 通常使用来去噪

常见滤波类型

均值滤波

math-4

高斯滤波 (权重与距离相关)

math-5

中值滤波

顾名思义取中值

具体代码例子

高斯的模糊/去噪效果
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# Read in the image
image = cv2.imread('images/brain_MR.jpg')

# Convert to grayscale for filtering
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

# Create a Gaussian blurred image
gray_blur = cv2.GaussianBlur(gray, (9, 9), 0)

# use custom kernal
# gaussian = (1/16)*np.array([[1, 2, 1],
#                            [2, 4, 2],
#                            [1, 2, 1]])
# 
# gray_blur = cv2.filter2D(gray, -1, gaussian)

f, (ax1, ax2) = plt.subplots(1, 2, figsize=(20,10))
ax1.set_title('original gray'),ax1.imshow(gray, cmap='gray')
ax2.set_title('blurred image'),ax2.imshow(gray_blur, cmap='gray')
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恢复git stash误删的内容

不小心使用 git drop stash 误删了暂存的内容 (或是 git stash pop 后丢失)，怎么恢复？

其实drop后并没有真正删除暂存的内容，而是移除了对它的引用，所以通过一些操作是可以找回的。

模拟误删场景

  • git st 查看当前修改

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    On branch master
    Your branch is up-to-date with 'origin/master'.
    Changes not staged for commit:
      (use "git add/rm <file>..." to update what will be committed)
      (use "git checkout -- <file>..." to discard changes in working directory)

        deleted:    calibration/adjust_result.json
        modified:   calibration/config.json
        modified:   calibration/src/rd_test.cc
        modified:   pose_estimation/CMakeLists.txt
        modified:   test/CMakeLists.txt
        modified:   test/multiple_sensors.json
        modified:   test/src/test_multiple_sensors.cc

  • git stash 暂存修改

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    Saved working directory and index state WIP on master: 4d74f8a fix spell
    HEAD is now at 4d74f8a fix spell

  • git stash list 查看暂存内容列表

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    stash@{0}: WIP on master: 4d74f8a fix spell

  • git stash drop stash@{0} 移除暂存内容

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    Dropped refs/stash@{0} (0b45536f1ce7e859a85f1459d6ae34fc6cdc4039)
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