kornia-slam 0.1.0

Real-time visual-inertial SLAM in Rust, built on kornia-rs.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137

use super::VerifiedLoopEdge;

/// Temporal and map-neighbourhood consistency required before a verified loop
/// becomes a pose-graph edge.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct LoopEpisodeConfig {
    pub min_consistent_edges: usize,
    pub max_query_gap: usize,
    pub candidate_neighborhood_radius: usize,
}

impl Default for LoopEpisodeConfig {
    fn default() -> Self {
        Self {
            min_consistent_edges: 3,
            max_query_gap: 5,
            candidate_neighborhood_radius: 10,
        }
    }
}

/// Decision produced for one geometrically verified observation.
#[derive(Debug, Clone, PartialEq)]
pub enum LoopEpisodeDecision {
    Pending {
        hits: usize,
        required: usize,
    },
    Ready {
        representative: VerifiedLoopEdge,
        hits: usize,
    },
    Suppressed {
        representative_query_kf_idx: usize,
        representative_candidate_kf_idx: usize,
    },
}

#[derive(Debug, Clone)]
struct LoopEpisode {
    candidate_anchor_order: usize,
    last_query_order: usize,
    hits: usize,
    representative: VerifiedLoopEdge,
    ready: bool,
}

/// Collapses adjacent verified observations into one physical revisit episode.
#[derive(Debug, Clone)]
pub struct LoopEpisodeTracker {
    config: LoopEpisodeConfig,
    current: Option<LoopEpisode>,
}

impl LoopEpisodeTracker {
    pub fn new(mut config: LoopEpisodeConfig) -> Self {
        config.min_consistent_edges = config.min_consistent_edges.max(1);
        Self {
            config,
            current: None,
        }
    }

    pub fn observe(
        &mut self,
        query_order: usize,
        candidate_order: usize,
        edge: VerifiedLoopEdge,
    ) -> LoopEpisodeDecision {
        let compatible = self.current.as_ref().is_some_and(|episode| {
            query_order >= episode.last_query_order
                && query_order - episode.last_query_order <= self.config.max_query_gap
                && candidate_order.abs_diff(episode.candidate_anchor_order)
                    <= self.config.candidate_neighborhood_radius
        });
        if !compatible {
            self.current = Some(LoopEpisode {
                candidate_anchor_order: candidate_order,
                last_query_order: query_order,
                hits: 1,
                representative: edge,
                ready: self.config.min_consistent_edges == 1,
            });
            let episode = self.current.as_ref().unwrap();
            return if episode.ready {
                LoopEpisodeDecision::Ready {
                    representative: episode.representative.clone(),
                    hits: episode.hits,
                }
            } else {
                LoopEpisodeDecision::Pending {
                    hits: episode.hits,
                    required: self.config.min_consistent_edges,
                }
            };
        }

        let episode = self.current.as_mut().unwrap();
        episode.last_query_order = query_order;
        if episode.ready {
            return LoopEpisodeDecision::Suppressed {
                representative_query_kf_idx: episode.representative.query_kf_idx,
                representative_candidate_kf_idx: episode.representative.candidate_kf_idx,
            };
        }
        episode.hits += 1;
        if edge_quality_better(&edge, &episode.representative) {
            episode.representative = edge;
        }
        if episode.hits >= self.config.min_consistent_edges {
            episode.ready = true;
            LoopEpisodeDecision::Ready {
                representative: episode.representative.clone(),
                hits: episode.hits,
            }
        } else {
            LoopEpisodeDecision::Pending {
                hits: episode.hits,
                required: self.config.min_consistent_edges,
            }
        }
    }
}

fn edge_quality_better(candidate: &VerifiedLoopEdge, current: &VerifiedLoopEdge) -> bool {
    candidate
        .inliers
        .cmp(&current.inliers)
        .then_with(|| candidate.inlier_ratio.total_cmp(&current.inlier_ratio))
        .then_with(|| candidate.occupied_cells.cmp(&current.occupied_cells))
        .then_with(|| {
            current
                .reprojection_rmse_px
                .total_cmp(&candidate.reprojection_rmse_px)
        })
        .is_gt()
}