Spatial Uncertainty Analytics for Budget-Limited Inspection of Hyperspectral Scenes
Organizations: Virginia Commonwealth University, Richmond, Virginia, USA
Abstract
Land-cover maps classified from wide-area hyperspectral surveys are least reliable along class boundaries and in ambiguous regions, so their errors are spatially structured. We study how this structure can direct a limited verification budget: when a low-altitude UAV or a ground crew can visit only a handful of sites, where it should go depends on how classifier uncertainty is arranged across the scene and how a fixed sensor footprint tiles that arrangement. We estimate a per-pixel uncertainty surface from the disagreement of an ensemble of spectral classifiers and select sites by greedy, field-of-view-aware coverage of the uncertainty mass. On seven benchmark scenes, the highest-uncertainty decile of pixels is 2.6 to 7.9 times richer in errors than the scene as a whole, and the coverage greedy covers up to 57% of the classifier's errors with 15 sites, 1.7 to 18 times as many as uncertainty-agnostic sampling of the same labelled region. A non-overlapping selection of the footprints richest in uncertainty does equally well, so the gain comes from scoring whole footprints by uncertainty mass. The advantage persists under spatially blocked evaluation and with a spectral-spatial classifier, although disagreement then ranks errors less well. It requires restricting the surface to labelled land cover: over the whole scene, disagreement peaks on unlabelled ground, where inspections cannot be scored. The best policy for covering connected high-uncertainty regions depends on the scene and on the threshold that defines them, and Gaussian-process selection covers less uncertainty than the coverage greedy on every scene. The pipeline runs on commodity CPUs.
Figures & tables
| Scene | GSD (m/px) | Footprint (m) | Area (m 2 ) |
| Indian Pines | |||
| Salinas | |||
| KSC | |||
| Pavia U. | |||
| LongKou | |||
| HanChuan |
| Scene | AUC | AUC (held-out) | AUC (blocked) | AP, held-out (prevalence) | Error rate | Top-10% error | Error where |
| Indian Pines | ( ) | ||||||
| Salinas | ( ) | ||||||
| KSC | ( ) | ||||||
| Pavia U. | ( ) | ||||||
| LongKou | ( ) | ||||||
| HanChuan | ( ) |
| Archival airborne | UAV-borne (WHU-Hi) | |||||||
| Strategy | Indian Pines | Salinas | KSC | Pavia U. | LongKou | HanChuan | HongHu | |
| Peak uncertainty | ||||||||
| Greedy coverage | ||||||||
| Unc.-wt. dispersion | ||||||||
| Unc.-ranked NMS | ||||||||
| Stratified unc. | ||||||||
| Archival airborne | UAV-borne (WHU-Hi) | |||||||
| Strategy | Indian Pines | Salinas | KSC | Pavia U. | LongKou | HanChuan | HongHu | |
| Peak uncertainty | ||||||||
| Greedy coverage | ||||||||
| Unc.-wt. dispersion | ||||||||
| Unc.-ranked NMS | ||||||||
| Stratified unc. | ||||||||
| Archival airborne | UAV-borne (WHU-Hi) | |||||||
| Strategy | Indian Pines | Salinas | KSC | Pavia U. | LongKou | HanChuan | HongHu | |
| Peak uncertainty | ||||||||
| Greedy coverage | ||||||||
| Unc.-wt. dispersion | ||||||||
| Unc.-ranked NMS | ||||||||
| Stratified unc. | ||||||||
| Scene | px | m | Test | AUC | Disp. | Best RM | Ratio |
| Indian Pines | |||||||
| Salinas | |||||||
| KSC |
| Archival airborne | UAV-borne (WHU-Hi) | |||||||
| Strategy | Indian Pines | Salinas | KSC | Pavia U. | LongKou | HanChuan | HongHu | |
| Peak uncertainty | ||||||||
| Greedy coverage | ||||||||
| Unc.-wt. dispersion | ||||||||
| Unc.-ranked NMS | ||||||||
| Stratified unc. | ||||||||
| Archival airborne | UAV-borne (WHU-Hi) | |||||||
| Strategy | Indian Pines | Salinas | KSC | Pavia U. | LongKou | HanChuan | HongHu | |
| Peak uncertainty | ||||||||
| Greedy coverage | ||||||||
| Unc.-wt. dispersion | ||||||||
| Unc.-ranked NMS | ||||||||
| Stratified unc. | ||||||||
| Margin at threshold | Components at | ||||
| Scene | |||||
| Indian Pines | |||||
| Salinas | |||||
| KSC | |||||
| Pavia U. | |||||
| LongKou | |||||
| Archival airborne | UAV-borne (WHU-Hi) | |||||||
| Strategy | Indian Pines | Salinas | KSC | Pavia U. | LongKou | HanChuan | HongHu | |
| Peak uncertainty | ||||||||
| Greedy coverage | ||||||||
| Unc.-wt. dispersion | ||||||||
| Unc.-ranked NMS | ||||||||
| Stratified unc. | ||||||||
| Archival airborne | UAV-borne (WHU-Hi) | |||||||
| Strategy | Indian Pines | Salinas | KSC | Pavia U. | LongKou | HanChuan | HongHu | |
| Peak uncertainty | ||||||||
| Greedy coverage | ||||||||
| Unc.-wt. dispersion | ||||||||
| Unc.-ranked NMS | ||||||||
| Stratified unc. | ||||||||
| Scene | Label mask | No mask | Novelty | Novelty | Novelty | Unlab. kept | On labels |
| Indian Pines | |||||||
| Salinas | |||||||
| KSC | |||||||
| Pavia U. | |||||||
| LongKou | |||||||
| HanChuan |
| Indian P. | Salinas | KSC | Pavia U. | LongKou | HanChuan | HongHu | |
| Uncertainty covered | |||||||
| Peak uncertainty | |||||||
| Greedy coverage | |||||||
| Dispersion | |||||||
| Lawnmower | |||||||
| Random | |||||||
| Strategy | Covered (%) | Path, selection order (km) | Path, 2-opt (km) | Covered per km |
| Peak uncertainty | ||||
| Greedy coverage | ||||
| Unc.-wt. dispersion | ||||
| Lawnmower, scene-wide | ||||
| Random, scene-wide |
| Main protocol | Blocked | ||||||||
| Scene | Features | Acc. | AUC | Disp. | Ratio | Acc. | AUC | Disp. | Ratio |
| Indian Pines | pixel | ||||||||
| spatial | |||||||||
| Salinas | pixel | ||||||||
| spatial | |||||||||
| Pavia U. | pixel | ||||||||
| Scene | Dispersion (ours) | GP-MI | GP-UCB | Random |
| Indian Pines | ||||
| Salinas | ||||
| KSC | ||||
| Pavia U. | ||||
| LongKou | ||||
| HanChuan |
Uncertainty Sampling
Uncertainty sampling selects data, queries, or computations where a model is least certain to improve learning or use limited resources efficiently.
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