This is the official repo for CVPR 2024 paper "BoQ: A Place is Worth a Bag of Learnable Queries"
BoQ is a new architecture for visual place recognition that employs a set of global learned queries (Bag-of-Queries) to probe the input’s local features via cross-attention, insuring consistent information aggregation.
[CVPR OpenAccess] [ArXiv] [BibTex]
The input image is first processed by a backbone network (ResNet for example) to extract its local features, which are then sequentially refined in cascade. Each BoQ block contains a set of learnable queries
We used GSV-Cities (https://github.com/amaralibey/gsv-cities) for training, with images resized to 320x320. We tested on 15 large scale benchmarks, as shown in the paper.
Our trained models are available on PyTorch Hub and can be downloaded and used without cloning this repo. Simply call the model using torch.hub.load as follows:
import torch
import torchvision.transforms as T
# ResNet50 + BoQ
vpr_model = torch.hub.load("amaralibey/bag-of-queries", "get_trained_boq", backbone_name="resnet50", output_dim=16384)
# DinoV2 + BoQ
vpr_model = torch.hub.load("amaralibey/bag-of-queries", "get_trained_boq", backbone_name="dinov2", output_dim=12288)
# NOTE: when using our models, use the following transform for best results.
im_size = (384, 384) # to be used with ResNet50 backbone
im_size = (322, 322) # to be used with DinoV2 backbone
def input_transform(image_size=im_size):
return T.Compose([
T.ToTensor(),
T.Resize(image_size, interpolation=T.InterpolationMode.BICUBIC, antialias=True),
T.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225]),
])We evaluated BoQ on 15 benchmarks. Below are the results when using ResNet50 and DinoV2 backbones.
╭─────────────── Recall@k Performance ───────────────╮
│ │
│ Dataset R@1 R@5 R@10 R@20 │
│ ───────────────────────────────────────────────── │
│ MSLS-val 93.8 96.8 97.0 97.7 │
│ Pitts30k-test 93.7 97.1 97.9 98.5 │
│ Pitts250k-test 96.6 99.1 99.5 99.7 │
│ Nordland* 81.3 92.5 94.8 96.3 │
│ Nordland** 90.6 96.0 97.5 98.5 │
│ SPED 92.5 95.9 96.7 98.0 │
│ AmesterTime 63.0 81.6 85.1 88.5 │
│ Eynsham 92.2 95.6 96.4 97.0 │
│ St-Lucia 99.9 100.0 100.0 100.0 │
│ Svox-night 97.7 99.5 99.8 99.9 │
│ Svox-sun 97.5 99.4 99.5 99.5 │
│ Svox-rain 98.8 99.7 99.8 99.8 │
│ Svox-snow 99.4 99.7 99.9 99.9 │
│ Svox-overcast 98.5 99.3 99.4 99.5 │
│ Svox-all 99.0 99.6 99.7 99.8 │
│----------------------------------------------------│
│ MSLS-Challenge 79.0 90.3 92.0 93.7 │
│ SF-Landmark 93.6 95.8 96.5 97.0 │
╰────────────────────────────────────────────────────╯
* 1-frame threshold
** 10-frames threshold
╭─────────────── Recall@k Performance ───────────────╮
│ │
│ Dataset R@1 R@5 R@10 R@20 │
│ ──────────────────────────────────────────────────│
│ MSLS-val 91.2 95.3 96.1 96.9 │
│ Pitts30k-test 92.4 96.5 97.4 98.1 │
│ Pitts250k-test 95.0 98.5 99.1 99.4 │
│ Nordland* 70.7 84.0 87.5 90.9 │
│ Nordland** 83.1 91.0 93.5 95.3 │
│ SPED 86.5 93.4 95.7 97.2 │
│ Eynsham 91.3 94.9 95.9 96.5 │
│ AmsterTime 52.2 72.5 78.4 82.5 │
│ St-Lucia 100.0 100.0 100.0 100.0 │
│ Svox-night 87.1 94.4 96.1 97.1 │
│ Svox-sun 95.9 98.8 98.9 99.2 │
│ Svox-rain 96.2 99.5 99.7 99.8 │
│ Svox-snow 98.7 99.5 99.7 99.8 │
│ Svox-overcast 97.8 99.2 99.3 99.4 │
│ Svox-all 98.9 99.4 99.6 99.7 │
╰────────────────────────────────────────────────────╯
* 1-frame threshold
** 10-frames threshold
The Bag-of-Queries (BoQ) technique is easy to implement. Here is the implementation in PyTorch. Note that the self-attention between the learned queries is there for stability purposes (it adds contexts between the learned queries during the training), it can be cached during eval.
Positional encoding are not really necessary (since the 3x3 conv operation is preceding the transformer). If you want to use a lot of BoQ blocks, you can add positional embeding to x just before the norm_input operation.
import torch
class BoQBlock(torch.nn.Module):
def __init__(self, in_dim, num_queries, nheads=8):
super(BoQBlock, self).__init__()
self.encoder = torch.nn.TransformerEncoderLayer(d_model=in_dim, nhead=nheads, dim_feedforward=4*in_dim, batch_first=True, dropout=0.)
self.queries = torch.nn.Parameter(torch.randn(1, num_queries, in_dim))
# the following two lines are used during training only, you can cache their output in eval.
self.self_attn = torch.nn.MultiheadAttention(in_dim, num_heads=nheads, batch_first=True)
self.norm_q = torch.nn.LayerNorm(in_dim)
#####
self.cross_attn = torch.nn.MultiheadAttention(in_dim, num_heads=nheads, batch_first=True)
self.norm_out = torch.nn.LayerNorm(in_dim)
def forward(self, x):
B = x.size(0)
x = self.encoder(x)
q = self.queries.repeat(B, 1, 1)
q = q + self.self_attn(q, q, q)[0]
q = self.norm_q(q)
out, attn = self.cross_attn(q, x, x)
out = self.norm_out(out)
return x, out, attn.detach()
class BoQ(torch.nn.Module):
def __init__(self, in_channels=1024, proj_channels=512, num_queries=32, num_layers=2, row_dim=32):
super().__init__()
self.proj_c = torch.nn.Conv2d(in_channels, proj_channels, kernel_size=3, padding=1)
self.norm_input = torch.nn.LayerNorm(proj_channels)
in_dim = proj_channels
self.boqs = torch.nn.ModuleList([
BoQBlock(in_dim, num_queries, nheads=in_dim//64) for _ in range(num_layers)])
self.fc = torch.nn.Linear(num_layers*num_queries, row_dim)
def forward(self, x):
# reduce input dimension using 3x3 conv when using ResNet
x = self.proj_c(x)
x = x.flatten(2).permute(0, 2, 1)
x = self.norm_input(x)
outs = []
attns = []
for i in range(len(self.boqs)):
x, out, attn = self.boqs[i](x)
outs.append(out)
attns.append(attn)
out = torch.cat(outs, dim=1)
out = self.fc(out.permute(0, 2, 1))
out = out.flatten(1)
out = torch.nn.functional.normalize(out, p=2, dim=-1)
return out, attnsStay tuned for the release of a new framework, for training and evaluating not only BoQ, but most existing VPR models. Don't forget to star the repo ;) but if you are in a hury, you can use GSV-Cities framework for training (https://github.com/amaralibey/gsv-cities), just copy the code into a new file (e.g. boq.py) into gsv-cities/models/aggregators/boq.py and import the class name in the __init__.py file.
Feel free to use the following bibtex code to cite or paper
@InProceedings{Ali-bey_2024_CVPR,
author = {Ali-bey, Amar and Chaib-draa, Brahim and Gigu\`ere, Philippe},
title = {{BoQ}: A Place is Worth a Bag of Learnable Queries},
booktitle = {Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR)},
month = {June},
year = {2024},
pages = {17794-17803}
}