如有错误,恳请指出。


在本地上,可以安装一些软件,比如:Meshlab,CloudCompare等3D查看工具来对点云进行可视化。而这篇博客是将介绍一些代码工具将KITTI数据集进行可视化操作,包括点云鸟瞰图,FOV图,以及标注信息在图像+点云上的显示。

文章目录

  • 1. 数据集准备
  • 2. 环境准备
  • 3. KITTI数据集可视化
  • 4. 点云可视化
  • 5. 鸟瞰图可视化

1. 数据集准备

KITTI数据集作为自动驾驶领域的经典数据集之一,比较适合我这样的新手入门。以下资料是为了实现对KITTI数据集的可视化操作。首先在官网下载对应的数据:http://www.cvlibs.net/datasets/kitti/eval_object.php?obj_benchmark=3d,下载后数据的目录文件结构如下所示:

├── dataset│ ├── KITTI│ │ ├── object│ │ │ ├──KITTI│ │ │├──ImageSets│ │ │ ├──training│ │ │├──calib & velodyne & label_2 & image_2

2. 环境准备

这里使用了一个kitti数据集可视化的开源代码:https://github.com/kuixu/kitti_object_vis,按照以下操作新建一个虚拟环境,并安装所需的工具包。其中千万不要安装python3.7以上的版本,因为vtk不支持。

# 新建python=3.7的虚拟环境conda create -n kitti_vis python=3.7 # vtk does not support python 3.8conda activate kitti_vis# 安装opencv, pillow, scipy, matplotlib工具包pip install opencv-python pillow scipy matplotlib# 安装3D可视化工具包(以下指令会自动安转所需的vtk与pyqt5)conda install mayavi -c conda-forge# 测试python kitti_object.py --show_lidar_with_depth --img_fov --const_box --vis

3. KITTI数据集可视化

下面依次展示 KITTI 数据集可视化结果,这里通过设置 data_idx=10 来展示编号为000010的数据,代码中dataset需要修改为数据集实际路径。(最后会贴上完整代码)

def visualization():import mayavi.mlab as mlabdataset = kitti_object(os.path.join(ROOT_DIR, '../dataset/KITTI/object'))# determine data_idxdata_idx = 100# Load data from datasetobjects = dataset.get_label_objects(data_idx) print("There are %d objects.", len(objects))img = dataset.get_image(data_idx) img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)img_height, img_width, img_channel = img.shape pc_velo = dataset.get_lidar(data_idx)[:,0:3]calib = dataset.get_calibration(data_idx) 

代码来源于参考资料,在后面会贴上我自己修改的测试代码。以下包含9种可视化的操作:

  • 1. 图像显示
def show_image(self):Image.fromarray(self.img).show()cv2.waitKey(0)

结果展示:

  • 2. 图片上绘制2D bbox
def show_image_with_2d_boxes(self):show_image_with_boxes(self.img, self.objects, self.calib, show3d=False)cv2.waitKey(0)

结果展示:

  • 3. 图片上绘制3D bbox
def show_image_with_3d_boxes(self):show_image_with_boxes(self.img, self.objects, self.calib, show3d=True)cv2.waitKey(0)

结果展示:

  • 4. 图片上绘制Lidar投影
def show_image_with_lidar(self):show_lidar_on_image(self.pc_velo, self.img, self.calib, self.img_width, self.img_height)mlab.show()

结果展示:

  • 5. Lidar绘制3D bbox
def show_lidar_with_3d_boxes(self):show_lidar_with_boxes(self.pc_velo, self.objects, self.calib, True, self.img_width, self.img_height)mlab.show()

结果展示:

  • 6. Lidar绘制FOV图
def show_lidar_with_fov(self):imgfov_pc_velo, pts_2d, fov_inds = get_lidar_in_image_fov(self.pc_velo, self.calib,0, 0, self.img_width, self.img_height, True)draw_lidar(imgfov_pc_velo)mlab.show()

结果展示:

  • 7. Lidar绘制3D图
def show_lidar_with_3dview(self):draw_lidar(self.pc_velo)mlab.show()

结果展示:

  • 8. Lidar绘制BEV图

BEV图的显示与其他视图不一样,这里的代码需要有点改动,因为这里需要lidar点云的其他维度信息,所以输入不仅仅是xyz三个维度。改动代码:

# 初始pc_velo = dataset.get_lidar(data_idx)[:, 0:3]# 改为(要增加其他维度才可以查看BEV视图)pc_velo = dataset.get_lidar(data_idx)[:, 0:4]

测试代码:

def show_lidar_with_bev(self):from kitti_util import draw_top_image, lidar_to_toptop_view = lidar_to_top(self.pc_velo)top_image = draw_top_image(top_view)cv2.imshow("top_image", top_image)cv2.waitKey(0)

结果展示:

  • 9. Lidar绘制BEV图+2D bbox

同样,这里的代码改动与3.8节一样,需要点云的其他维度信息

def show_lidar_with_bev_2d_bbox(self):show_lidar_topview_with_boxes(self.pc_velo, self.objects, self.calib)mlab.show()

结果展示:

  • 完整测试代码

参考代码:

import mayavi.mlab as mlabfrom kitti_object import kitti_object, show_image_with_boxes, show_lidar_on_image, \show_lidar_with_boxes, show_lidar_topview_with_boxes, get_lidar_in_image_fov, \show_lidar_with_depthfrom viz_util import draw_lidarimport cv2from PIL import Imageimport timeclass visualization:# data_idx: determine data_idxdef __init__(self, root_dir=r'E:\Study\Machine Learning\Dataset3d\kitti', data_idx=100):dataset = kitti_object(root_dir=root_dir)# Load data from datasetobjects = dataset.get_label_objects(data_idx)print("There are {} objects.".format(len(objects)))img = dataset.get_image(data_idx)img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)img_height, img_width, img_channel = img.shapepc_velo = dataset.get_lidar(data_idx)[:, 0:3]# 显示bev视图需要改动为[:, 0:4]calib = dataset.get_calibration(data_idx)# init the paramsself.objects = objectsself.img = imgself.img_height = img_heightself.img_width = img_widthself.img_channel = img_channelself.pc_velo = pc_veloself.calib = calib# 1. 图像显示def show_image(self):Image.fromarray(self.img).show()cv2.waitKey(0)# 2. 图片上绘制2D bboxdef show_image_with_2d_boxes(self):show_image_with_boxes(self.img, self.objects, self.calib, show3d=False)cv2.waitKey(0)# 3. 图片上绘制3D bboxdef show_image_with_3d_boxes(self):show_image_with_boxes(self.img, self.objects, self.calib, show3d=True)cv2.waitKey(0)# 4. 图片上绘制Lidar投影def show_image_with_lidar(self):show_lidar_on_image(self.pc_velo, self.img, self.calib, self.img_width, self.img_height)mlab.show()# 5. Lidar绘制3D bboxdef show_lidar_with_3d_boxes(self):show_lidar_with_boxes(self.pc_velo, self.objects, self.calib, True, self.img_width, self.img_height)mlab.show()# 6. Lidar绘制FOV图def show_lidar_with_fov(self):imgfov_pc_velo, pts_2d, fov_inds = get_lidar_in_image_fov(self.pc_velo, self.calib,0, 0, self.img_width, self.img_height, True)draw_lidar(imgfov_pc_velo)mlab.show()# 7. Lidar绘制3D图def show_lidar_with_3dview(self):draw_lidar(self.pc_velo)mlab.show()# 8. Lidar绘制BEV图def show_lidar_with_bev(self):from kitti_util import draw_top_image, lidar_to_toptop_view = lidar_to_top(self.pc_velo)top_image = draw_top_image(top_view)cv2.imshow("top_image", top_image)cv2.waitKey(0)# 9. Lidar绘制BEV图+2D bboxdef show_lidar_with_bev_2d_bbox(self):show_lidar_topview_with_boxes(self.pc_velo, self.objects, self.calib)mlab.show()if __name__ == '__main__':kitti_vis = visualization()# kitti_vis.show_image()# kitti_vis.show_image_with_2d_boxes()# kitti_vis.show_image_with_3d_boxes()# kitti_vis.show_image_with_lidar()# kitti_vis.show_lidar_with_3d_boxes()# kitti_vis.show_lidar_with_fov()# kitti_vis.show_lidar_with_3dview()# kitti_vis.show_lidar_with_bev()kitti_vis.show_lidar_with_bev_2d_bbox()# print('...')# cv2.waitKey(0)

此外,下面再提供两份可视化代码。


4. 点云可视化

这里的同样使用的是上述的图例,且直接输入的KITTI数据集的.bin文件,即可显示点云图像。

  • 参考代码:
import numpy as npimport mayavi.mlabimport os# 000010.bin这里需要填写文件的位置# bin_file = '../data/object/training/velodyne/000000.bin'# assert os.path.exists(bin_file), "{} is not exists".format(bin_file)kitti_file = r'E:\Study\Machine Learning\Dataset3d\kitti\training\velodyne\000100.bin'pointcloud = np.fromfile(file=kitti_file, dtype=np.float32, count=-1).reshape([-1, 4])# pointcloud = np.fromfile(str("000010.bin"), dtype=np.float32, count=-1).reshape([-1, 4])print(pointcloud.shape)x = pointcloud[:, 0]# x position of pointy = pointcloud[:, 1]# y position of pointz = pointcloud[:, 2]# z position of pointr = pointcloud[:, 3]# reflectance value of pointd = np.sqrt(x ** 2 + y ** 2)# Map Distance from sensorvals = 'height'if vals == "height":col = zelse:col = dfig = mayavi.mlab.figure(bgcolor=(0, 0, 0), size=(640, 500))mayavi.mlab.points3d(x, y, z, col,# Values used for Color mode="point", colormap='spectral',# 'bone', 'copper', 'gnuplot' # color=(0, 1, 0), # Used a fixed (r,g,b) instead figure=fig, )x = np.linspace(5, 5, 50)y = np.linspace(0, 0, 50)z = np.linspace(0, 5, 50)mayavi.mlab.plot3d(x, y, z)mayavi.mlab.show()
  • 输出结果:

ps:这里的输出点云结果相比上面的点云输出结果更加的完善,而且参考的中心坐标点也不一样。


5. 鸟瞰图可视化

代码中的鸟瞰图范围可以自行设置。同样,输入的也只需要是.bin文件即可展示其鸟瞰图。

  • 参考代码:
import numpy as npfrom PIL import Imageimport matplotlib.pyplot as plt# 点云读取:000010.bin这里需要填写文件的位置kitti_file = r'E:\Study\Machine Learning\Dataset3d\kitti\training\velodyne\000100.bin'pointcloud = np.fromfile(file=kitti_file, dtype=np.float32, count=-1).reshape([-1, 4])# 设置鸟瞰图范围side_range = (-40, 40)# 左右距离# fwd_range = (0, 70.4)# 后前距离fwd_range = (-70.4, 70.4)x_points = pointcloud[:, 0]y_points = pointcloud[:, 1]z_points = pointcloud[:, 2]# 获得区域内的点f_filt = np.logical_and(x_points > fwd_range[0], x_points < fwd_range[1])s_filt = np.logical_and(y_points > side_range[0], y_points < side_range[1])filter = np.logical_and(f_filt, s_filt)indices = np.argwhere(filter).flatten()x_points = x_points[indices]y_points = y_points[indices]z_points = z_points[indices]res = 0.1# 分辨率0.05mx_img = (-y_points / res).astype(np.int32)y_img = (-x_points / res).astype(np.int32)# 调整坐标原点x_img -= int(np.floor(side_range[0]) / res)y_img += int(np.floor(fwd_range[1]) / res)print(x_img.min(), x_img.max(), y_img.min(), x_img.max())# 填充像素值height_range = (-2, 0.5)pixel_value = np.clip(a=z_points, a_max=height_range[1], a_min=height_range[0])def scale_to_255(a, min, max, dtype=np.uint8):return ((a - min) / float(max - min) * 255).astype(dtype)pixel_value = scale_to_255(pixel_value, height_range[0], height_range[1])# 创建图像数组x_max = 1 + int((side_range[1] - side_range[0]) / res)y_max = 1 + int((fwd_range[1] - fwd_range[0]) / res)im = np.zeros([y_max, x_max], dtype=np.uint8)im[y_img, x_img] = pixel_value# imshow (灰度)im2 = Image.fromarray(im)im2.show()# imshow (彩色)# plt.imshow(im, cmap="nipy_spectral", vmin=0, vmax=255)# plt.show()
  • 结果展示:


后续的工作会加深对点云数据的理解,整个可视化项目的工程见:KITTI数据集的可视化项目,有需要的朋友可以自行下载。


参考资料:

1. KITTI自动驾驶数据集可视化教程

2. kitti数据集在3D目标检测中的入门

3. kitti数据集在3D目标检测中的入门(二)可视化详解

4. kitti_object_vis项目