Question about exhaustive_voting

[HuangSenPKU]

Hello, why is valid_bev.unsqueeze(1) used in f_bev = f_bev.masked_fill(~valid_bev.unsqueeze(1), 0.0) in the exhaustive_voting function, while valid_bev.float()[None] is used in valid_templates = self.template_sampler(valid_bev.float()[None])?

def exhaustive_voting(self, f_bev, f_map, valid_bev, confidence_bev=None):
if self.conf.normalize_features:
f_bev = normalize(f_bev, dim=1)
f_map = normalize(f_map, dim=1)

    # Build the templates and exhaustively match against the map.
    if confidence_bev is not None:
        f_bev = f_bev * confidence_bev.unsqueeze(1)
    f_bev = f_bev.masked_fill(~valid_bev.unsqueeze(1), 0.0)
    templates = self.template_sampler(f_bev)
    with torch.autocast("cuda", enabled=False):
        scores = conv2d_fft_batchwise(
            f_map.float(),
            templates.float(),
            padding_mode=self.conf.padding_matching,
        )
    if self.conf.add_temperature:
        scores = scores * torch.exp(self.temperature)

Reweight the different rotations based on the number of valid pixels in each

    # template. Axis-aligned rotation have the maximum number of valid pixels.
    valid_templates = self.template_sampler(valid_bev.float()[None) > (1 - 1e-4) 

    num_valid = valid_templates.float().sum((-3, -2, -1))
    scores = scores / num_valid[..., None, None]
    return scores