gim-online / hloc /matchers /dual_softmax.py
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import torch
from ..utils.base_model import BaseModel
import numpy as np
# borrow from dedode
def dual_softmax_matcher(
desc_A: tuple["B", "C", "N"],
desc_B: tuple["B", "C", "M"],
threshold=0.1,
inv_temperature=20,
normalize=True,
):
B, C, N = desc_A.shape
if len(desc_A.shape) < 3:
desc_A, desc_B = desc_A[None], desc_B[None]
if normalize:
desc_A = desc_A / desc_A.norm(dim=1, keepdim=True)
desc_B = desc_B / desc_B.norm(dim=1, keepdim=True)
sim = (
torch.einsum("b c n, b c m -> b n m", desc_A, desc_B) * inv_temperature
)
P = sim.softmax(dim=-2) * sim.softmax(dim=-1)
mask = torch.nonzero(
(P == P.max(dim=-1, keepdim=True).values)
* (P == P.max(dim=-2, keepdim=True).values)
* (P > threshold)
)
mask = mask.cpu().numpy()
matches0 = np.ones((B, P.shape[-2]), dtype=int) * (-1)
scores0 = np.zeros((B, P.shape[-2]), dtype=float)
matches0[:, mask[:, 1]] = mask[:, 2]
tmp_P = P.cpu().numpy()
scores0[:, mask[:, 1]] = tmp_P[mask[:, 0], mask[:, 1], mask[:, 2]]
matches0 = torch.from_numpy(matches0).to(P.device)
scores0 = torch.from_numpy(scores0).to(P.device)
return matches0, scores0
class DualSoftMax(BaseModel):
default_conf = {
"match_threshold": 0.2,
"inv_temperature": 20,
}
# shape: B x DIM x M
required_inputs = ["descriptors0", "descriptors1"]
def _init(self, conf):
pass
def _forward(self, data):
if (
data["descriptors0"].size(-1) == 0
or data["descriptors1"].size(-1) == 0
):
matches0 = torch.full(
data["descriptors0"].shape[:2],
-1,
device=data["descriptors0"].device,
)
return {
"matches0": matches0,
"matching_scores0": torch.zeros_like(matches0),
}
matches0, scores0 = dual_softmax_matcher(
data["descriptors0"],
data["descriptors1"],
threshold=self.conf["match_threshold"],
inv_temperature=self.conf["inv_temperature"],
)
return {
"matches0": matches0, # 1 x M
"matching_scores0": scores0,
}