[英]How to extract the bottom layer voxels using open3d?
I want to extract the bottom layer voxels.我想提取底层体素。 For example, extract the part from the armadillo.
例如,从犰狳中提取部分。 Does anyone know how to do that?
有谁知道这是怎么做到的吗?
This is how I find the lowest voxel.这就是我找到最低体素的方法。
#Get voxels center coordinate
def get_voxel_center_coordinate(voxel_grid):
voxels = voxel_grid.get_voxels()
voxel_center = []
for voxel in voxels:
voxel_center.append(voxel_grid.get_voxel_center_coordinate(voxel.grid_index))
return voxel_center
#Find lowest voxels index
def find_lowest_voxel_index(voxel_grid):
voxels = voxel_grid.get_voxels()
voxel_center = get_voxel_center_coordinate(voxel_grid)
for i in range(0, len(voxel_center)):
if i == 0:
min_z = voxel_center[i, 2]
else:
if min_z > voxel_center[i, 2]:
min_z = voxel_center[i, 2]
ind = 0
lowest_voxel_index = []
for center in voxel_center:
if center[2] == min_z:
print(center[2])
lowest_voxel_index.append(voxels[ind].grid_index)
ind += 1
return lowest_voxel_index
Your solution is almost correct.您的解决方案几乎是正确的。 I'll point out a few things that you should change and then a way to verify the solution.
我会指出一些你应该改变的事情,然后是一种验证解决方案的方法。
Things that should change in the given solution:给定解决方案中应该改变的事情:
voxel_center[i, 2]
since voxel_center
is a list, not a numpy array.voxel_center[i, 2]
访问 z 轴,因为voxel_center
是一个列表,而不是一个 numpy 数组。 You should instead access them as voxel_center[i][2]
.voxel_center[i][2]
的形式访问它们。ind
at each loop, not only when the condition is true.ind
,而不仅仅是在条件为真时。 Alternatively, you can use enumerate
which overcomes this cleanly.enumerate
干净地克服了这个问题。 Therefore, the correct implementation would be the following:因此,正确的实现如下:
#Get voxels center coordinate
def get_voxel_center_coordinate(voxel_grid):
voxels = voxel_grid.get_voxels()
voxel_center = []
for voxel in voxels:
voxel_center.append(voxel_grid.get_voxel_center_coordinate(voxel.grid_index))
return voxel_center
#Find lowest voxels index
def find_lowest_voxel_index(voxel_grid):
voxels = voxel_grid.get_voxels()
voxel_center = get_voxel_center_coordinate(voxel_grid)
for i in range(0, len(voxel_center)):
if i == 0:
min_z = voxel_center[i][2]
else:
if min_z > voxel_center[i][2]:
min_z = voxel_center[i][2]
ind = 0
lowest_voxel_index = []
for center in voxel_center:
if center[2] == min_z:
print(center[2])
lowest_voxel_index.append(voxels[ind].grid_index)
ind += 1
return lowest_voxel_index
To verify the solution, you might want to visualize the results.要验证解决方案,您可能需要可视化结果。 However,
VoxelGrid
does not have any method that allows the user to eg, change the color of a particular voxel.然而,
VoxelGrid
没有任何方法允许用户更改特定体素的颜色。 Therefore, you can think of creating extra meshes to visualize the filtered voxels.因此,您可以考虑创建额外的网格来可视化过滤后的体素。 Since
VoxelGrid
provides get_voxel_bounding_points
, you can make use of these points to create an AxisAlignedBoundingBox
.由于
VoxelGrid
提供get_voxel_bounding_points
,您可以利用这些点来创建AxisAlignedBoundingBox
。
lowest_index = find_lowest_voxel_index(voxel_grid) # this uses your solution after modifications
bounding_box = []
for i in lowest_index:
bb = o3d.geometry.AxisAlignedBoundingBox.create_from_points(voxel_grid.get_voxel_bounding_points(i))
bb.color = np.array([1,0,1]) # feel free to choose any other color
bounding_box.append(bb)
axes = o3d.geometry.TriangleMesh.create_coordinate_frame(origin=np.array([100,100,100]), size=100) # in order to be sure of the direction
o3d.visualization.draw_geometries([voxel_grid, *bounding_box, axes])
This is how running this code on an armadillo mesh looks like.这就是在犰狳网格上运行此代码的样子。 Note that I added the coordinate frame to make sure of the direction.
请注意,我添加了坐标系以确保方向。 Blue arrow points toward +z.
蓝色箭头指向 +z。 The voxel with the lowest z value has purple edges.
z 值最低的体素具有紫色边缘。
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