def generate_sampling_points(self, boxes):
'''
boxes: [num_boxes, 4, 2]
'''
num_boxes = boxes.size(0)
num_points = 7 # 这里生成7x7的采样空间
# 生成网格坐标
x = torch.linspace(-0.5, 0.5, num_points)
y = torch.linspace(-0.5, 0.5, num_points)
grid_x, grid_y = torch.meshgrid(x, y) # 形状为 [num_points, num_points]
# 将网格坐标扩展为每个box的采样点坐标
grid_x = grid_x.view(1, num_points, num_points).expand(num_boxes, -1, -1)
grid_y = grid_y.view(1, num_points, num_points).expand(num_boxes, -1, -1)
# 计算每个box的中心坐标和宽高
center_x = (boxes[:, 0, 0] + boxes[:, 2, 0]) / 2.0
center_y = (boxes[:, 0, 1] + boxes[:, 2, 1]) / 2.0
width = boxes[:, 2, 0] - boxes[:, 0, 0]
height = boxes[:, 2, 1] - boxes[:, 0, 1]
# 根据box的中心坐标和宽高计算采样点坐标
sample_x = center_x.view(num_boxes, 1, 1) + grid_x * width.view(num_boxes, 1, 1)
sample_y = center_y.view(num_boxes, 1, 1) + grid_y * height.view(num_boxes, 1, 1)
# 组合采样点的x和y坐标
sampling_points = torch.stack([sample_x, sample_y], dim=3) # 形状为 [num_boxes, num_points, num_points, 2]
# 将采样点坐标展平成形状为 [num_boxes, num_points*num_points, 2] 的张量
sampling_points = sampling_points.view(num_boxes, -1, 2)
return sampling_points
下面是使用PyTorch生成给定n个box中的7x7等间距采样空间,并生成一个形状为[n, 49, 2]的采样点集合的示例代码:
import torch
def generate_sampling_points(boxes):
num_boxes = boxes.size(0)
num_points = 7
# 生成网格坐标
x = torch.linspace(-0.5, 0.5, num_points)
y = torch.linspace(-0.5, 0.5, num_points)
grid_x, grid_y = torch.meshgrid(x, y) # 形状为 [num_points, num_points]
# 将网格坐标扩展为每个box的采样点坐标
grid_x = grid_x.view(1, num_points, num_points).expand(num_boxes, -1, -1)
grid_y = grid_y.view(1, num_points, num_points).expand(num_boxes, -1, -1)
# 计算每个box的中心坐标和宽高
center_x = (boxes[:, 0, 0] + boxes[:, 2, 0]) / 2.0
center_y = (boxes[:, 0, 1] + boxes[:, 2, 1]) / 2.0
width = boxes[:, 2, 0] - boxes[:, 0, 0]
height = boxes[:, 2, 1] - boxes[:, 0, 1]
# 根据box的中心坐标和宽高计算采样点坐标
sample_x = center_x.view(num_boxes, 1, 1) + grid_x * width.view(num_boxes, 1, 1)
sample_y = center_y.view(num_boxes, 1, 1) + grid_y * height.view(num_boxes, 1, 1)
# 组合采样点的x和y坐标
sampling_points = torch.stack([sample_x, sample_y], dim=3) # 形状为 [num_boxes, num_points, num_points, 2]
# 将采样点坐标展平成形状为 [num_boxes, num_points*num_points, 2] 的张量
sampling_points = sampling_points.view(num_boxes, -1, 2)
return sampling_points
# 示例使用
# 假设有2个box,每个box的顶点坐标为 4x2 的张量
boxes = torch.tensor([
[[0.2, 0.3], [0.4, 0.3], [0.4, 0.5], [0.2, 0.5]], # box 1
[[-0.3, -0.4], [-0.1, -0.4], [-0.1, -0.2], [-0.3, -0.2]] # box 2
])
sampling_points = generate_sampling_points(boxes)
print(sampling_points.shape) # 输出: torch.Size([2, 49, 2])
在上述示例代码中,generate_sampling_points
函数接受一个张量boxes
,其形状为 [n, 4, 2]
,其中n
是box的数量。函数首先生成一个7
x7的等间距网格坐标,然后根据每个box的中心坐标和宽高计算采样点的坐标。最后,将采样点的坐标展平成形状为 [n, 49, 2]
的张量,并返回该结果。
请注意,示例代码中的坐标范围是在 [-0.5, 0.5] 内进行归一化处理,以适应等间距的网格。如果你的实际应用需要不同的坐标范围或网格密度,可以相应地进行调整。
参考: