软件工程应用与实践（6）可视化-交互功能

2021SC@SDUSC 

open3d 

open3d中可视化窗口的交互功能的实现

import numpy as np
import copy
import open3d as o3d


def demo_crop_geometry():
    print("Demo for manual geometry cropping")
    print(
        "1) Press 'Y' twice to align geometry with negative direction of y-axis"
    )
    print("2) Press 'K' to lock screen and to switch to selection mode")
    print("3) Drag for rectangle selection,")
    print("   or use ctrl + left click for polygon selection")
    print("4) Press 'C' to get a selected geometry and to save it")
    print("5) Press 'F' to switch to freeview mode")
    pcd = o3d.io.read_point_cloud("ICP/cloud_bin_0.pcd")
    o3d.visualization.draw_geometries_with_editing([pcd])


def draw_registration_result(source, target, transformation):
    source_temp = copy.deepcopy(source)
    target_temp = copy.deepcopy(target)
    source_temp.paint_uniform_color([1, 0.706, 0])
    target_temp.paint_uniform_color([0, 0.651, 0.929])
    source_temp.transform(transformation)
    o3d.visualization.draw_geometries([source_temp, target_temp])


def pick_points(pcd):
    print("")
    print(
        "1) Please pick at least three correspondences using [shift + left click]"
    )
    print("   Press [shift + right click] to undo point picking")
    print("2) After picking points, press 'Q' to close the window")
    vis = o3d.visualization.VisualizerWithEditing()
    vis.create_window()
    vis.add_geometry(pcd)
    vis.run()  # user picks points
    vis.destroy_window()
    print("")
    return vis.get_picked_points()


def demo_manual_registration():
    print("Demo for manual ICP")
    source = o3d.io.read_point_cloud("ICP/cloud_bin_0.pcd")
    target = o3d.io.read_point_cloud("ICP/cloud_bin_2.pcd")
    print("Visualization of two point clouds before manual alignment")
    draw_registration_result(source, target, np.identity(4))

    # pick points from two point clouds and builds correspondences
    picked_id_source = pick_points(source)
    picked_id_target = pick_points(target)
    assert (len(picked_id_source) >= 3 and len(picked_id_target) >= 3)
    assert (len(picked_id_source) == len(picked_id_target))
    corr = np.zeros((len(picked_id_source), 2))
    corr[:, 0] = picked_id_source
    corr[:, 1] = picked_id_target

    # estimate rough transformation using correspondences
    print("Compute a rough transform using the correspondences given by user")
    p2p = o3d.pipelines.registration.TransformationEstimationPointToPoint()
    trans_init = p2p.compute_transformation(source, target,
                                            o3d.utility.Vector2iVector(corr))

    # point-to-point ICP for refinement
    print("Perform point-to-point ICP refinement")
    threshold = 0.03  # 3cm distance threshold
    reg_p2p = o3d.pipelines.registration.registration_icp(
        source, target, threshold, trans_init,
        o3d.pipelines.registration.TransformationEstimationPointToPoint())
    draw_registration_result(source, target, reg_p2p.transformation)
    print("")


if __name__ == "__main__":
    demo_crop_geometry()
    demo_manual_registration()

执行了两个用户交互应用程序: demo_crop_geometry()和demo_manual_registration()。

def demo_crop_geometry():
    print("Demo for manual geometry cropping")
    print(
        "1) Press 'Y' twice to align geometry with negative direction of y-axis"
    )
    print("2) Press 'K' to lock screen and to switch to selection mode")
    print("3) Drag for rectangle selection,")
    print("   or use ctrl + left click for polygon selection")
    print("4) Press 'C' to get a selected geometry and to save it")
    print("5) Press 'F' to switch to freeview mode")
    pcd = o3d.io.read_point_cloud("../../test_data/ICP/cloud_bin_0.pcd")
    o3d.visualization.draw_geometries_with_editing([pcd])

这个函数简单读取了一个点云数据然后调用了draw_geometries_with_editing 函数，该函数提供了顶点选择和裁剪功能。

Open3d有一个继承visualizer类的visualizerwithEditing类。它提供了图形用户交互功能。同样的例子在自定义可视化中, visualizerwithEditing()是可以显式的替换掉draw_geometries_with_editing([pcd])。 

上述函数之后可以在open3d中对几何体进行相应的操作最终实现裁剪的效果。 

def pick_points(pcd):
    print("")
    print(
        "1) Please pick at least three correspondences using [shift + left click]"
    )
    print("   Press [shift + right click] to undo point picking")
    print("2) After picking points, press 'Q' to close the window")
    vis = o3d.visualization.VisualizerWithEditing()
    vis.create_window()
    vis.add_geometry(pcd)
    vis.run()  # user picks points
    vis.destroy_window()
    print("")
    return vis.get_picked_points()

函数pick_points(pcd)创造了一个VisualizerwithEditing实例去模仿draw_geometries，创造可视化窗口，添加几何图形，可视化几何图形和结束。VisualizerwithEditing 提供一种新的交互函数get_picked_points()，该函数可以返回用户选取的顶点的索引