A Scene, represented visually using different formats such as RGB-D, LiDAR scan, keypoints, rectangular, spherical, multi-views, etc., contains information implicitly embedded relevant to applications such as scene indexing, vision-based navigation. Thus, these representations may not be efficient for such applications. This paper proposes a novel 360° saliency graph representation of the scenes. This rich representation explicitly encodes the relevant visual, contextual, semantic, and geometric information of the scene as nodes, edges, edge weights, and angular position in the 360° graph. Also, this representation is robust against scene view change and addresses challenges of indoor environments such as varied illumination, occlusions, and shadows as in the case of existing traditional methods. We have utilized this rich and efficient representation for vision-based navigation and compared it with existing navigation methods using 360° scenes. However, these existing methods suffer from limitations of poor scene representation, lacking scene-specific information. This work utilizes the proposed representation first to localize the query scene in the given topological map, and then facilitate 2D navigation by estimating the next required movement directions towards the target destination in the topological map by using the embedded geometric information in the 360° saliency graph. Experimental results demonstrate the efficacy of the proposed 360° saliency graph representation in enhancing both scene localization and vision-based indoor navigation.
Figures & tables
Fig. 1: (A) Orientation-rich 360∘ saliency graph representation of a scene, constructed from an RGB-D panorama image. (B) Localization in a topological map and positioning within a localized scene using 360∘ saliency graphs. Localization: via scene graph matching using visual, semantic, and contextual information embedded in the 3600 saliency graph; Positioning in the scene: by aligning geometric information in a 3600 saliency graph.
Fig. 2: Overall framework of the proposed method for Queryable Topological Map Generation , and Scene Localization . For Queryable Topological Map Generation , a building is processed to extract the floor map (a 2D layout of the building), the region semantic mask (a segmentation mask labeling larger semantic regions such as rooms and hallways), and the object semantic mask (a finer-grained segmentation mask labeling individual objects) to construct a queryable topological map T that facilitates the navigation path/topological connection between the scene locations V (nodes in red and scene transition nodes in blue). At each scene location in V , an orientation-rich 360∘ saliency graph G is generated from an RGB-D panorama image as a scene representation. In Scene Localization , a query panoramic RGB-D image of a scene is localized within the topological map T . For this, the query 360∘ saliency graph is constructed from the query image and matched against the precomputed saliency graphs G associated with the map nodes to extract the location with the highest similarity above a minimum threshold. Afterwards, positioning is performed by aligning the 360∘ saliency graphs of query and reference scenes to estimate the directions for navigation towards the target destination on the topological map.
Fig. 3: Alignment of query graph Gq and matched candidate graph Gm by estimating shift Δ and orientation using underlying geometry of reference points ( c , c′ ) and matched salient objects.
Fig. 4: Sample panorama images for different viewer positions and orientation difference ( θe ).
# of instances
Ep
Eθ
105
0.6995 m
16.590
TABLE I: Mean position ( Ep ) and orientation ( Eθ ) errors, computed between shifted and original/ground-truth poses.
Fig. 5: An example of navigation on topological map. First, determine current orientation θc at the current location (Xc,Yc) using the saliency graph after performing localization. Next, the rotation angle θr between the direction of the topological path and θc is calculated after performing alignment using positioning. The navigation algorithm then adjusts the heading based on this θr , ensuring accurate movement towards the next target location (Xt,Yt) on the shortest path algorithm.
Methods
MMA@3
Methods
MMA@3
SP [ 50 ] +NN
32.43
QuadT [ 55 ]
41.72
SP [ 50 ] +SG [ 53 ]
29.95
LoFTR [ 56 ]
36.07
ASLFeat [ 52 ] +NN
35.79
COTR [ 57 ]
46.07
ALike [ 51 ] +NN
34.55
GT+SGAM_COTR [ 58 ]
49.82
ASpan [ 54 ]
37.25
Proposed
87.8
TABLE II: Localization performance comparison in terms of MMA @3 with state-of-the-art feature matching-based methods.
Methods
LDL [ 59 ]
FGPL [ 60 ]
MiC [ 43 ]
MFP-CNN [ 61 ]
SOVS [ 17 ]
Proposed
Acc ( ↑ )
0.35
0.71
0.78
0.80
0.82
0.86
TABLE III: Comparison of mean accuracy for scene localization.
TABLE IV: Sample results for scene localization.
Method
f
2f
3f
SOVS [ 17 ]
0.47
0.36
0.29
Proposed
0.65
0.50
0.42
TABLE V: Robustness of scene localization accuracy under varied focal length.
Fig. 6: An example of proposed localization + MiC [ 43 ] navigation method.
Methods
Navigation Acc.
OSR( ↑ )
SR( ↑ )
SPL( ↑ )
FAST-MATTN [ 39 ]
28.20
14.40
7.19
CKR [ 15 ]
31.44
19.14
11.84
Airbert [ 40 ]
34.51
27.89
21.88
HOP [ 41 ]
36.24
31.78
26.11
DUET [ 42 ]
51.07
46.98
33.73
TABLE VI: Impact of proposed localization method on navigation performance.
Fig. 7: An example showing the room-type prediction using MiC [ 43 ] and proposed localization method.
Methods
Navigation Acc.
SR( ↑ )
SPL( ↑ )
MiC [ 43 ]
56.97
43.60
Proposed Navigation
76.92
72.85
TABLE VII: Performance comparison of proposed navigation framework against MiC [ 43 ] .
Methods
Image
Objects
Salient objects
USG
360∘ saliency graph
Acc ( ↑ )
0.68
0.76
0.82
0.84
0.86
TABLE VIII: Impact of different components on localization. (USG: unweighted saliency graph)
Method
without 3600 saliency graph
with 3600 saliency graph
SR
58.73
76.92
TABLE IX: Impact of 3600 saliency graph-based positioning on navigation performance.
Department of Engineering Science, University of Oxford, UK · Department of Mechanical Engineering, Seoul National University, South Korea · School of Informatics, University of Edinburgh, UK