net_utils.py 文件源码

def _affine_grid_gen(rois, input_size, grid_size):

    rois = rois.detach()
    x1 = rois[:, 1::4] / 16.0
    y1 = rois[:, 2::4] / 16.0
    x2 = rois[:, 3::4] / 16.0
    y2 = rois[:, 4::4] / 16.0

    height = input_size[0]
    width = input_size[1]

    zero = Variable(rois.data.new(rois.size(0), 1).zero_())
    theta = torch.cat([\
      (x2 - x1) / (width - 1),
      zero,
      (x1 + x2 - width + 1) / (width - 1),
      zero,
      (y2 - y1) / (height - 1),
      (y1 + y2 - height + 1) / (height - 1)], 1).view(-1, 2, 3)

    grid = F.affine_grid(theta, torch.Size((rois.size(0), 1, grid_size, grid_size)))

    return grid