Speaker
Description
Receiver-reported Global Navigation Satellite System (GNSS) accuracy metrics (e.g., horizontal accuracy estimates derived from solution covariance) are sometimes used as proxies for positional reliability in forestry applications. However, their predictive validity under canopy and obstruction remains insufficiently quantified. This study evaluates the relationship between receiver-reported accuracy and empirically observed positioning error across four static environment classes representative of forestry sector conditions.
Static occupations were conducted on pre-surveyed control points in forest interior, forest edge, tree-adjacent, and building-adjacent environments. Horizontal error was quantified using Distance Root Mean Squared (DRMS), the average value for stand conditions reaching 2.3 meters. Error distributions were strongly non-normal in all environments (Shapiro–Wilk p < 0.001). Correlation between reported accuracy and DRMS was highly environment-dependent. In dense forest interior, linear predictive power was negligible (R² = 0.002; Pearson r = -0.05; Spearman ρ = 0.14). At forest edge, explanatory power remained minimal (R² = 0.005; Pearson r = 0.07; Spearman ρ = -0.44). In contrast, minor associations were observed in building-adjacent (R² = 0.10; Pearson r = 0.32; Spearman ρ = 0.51) and tree-adjacent conditions (R² = 0.19; Pearson r = 0.44), indicating partial covariance tracking under certain obstruction geometries.
Despite these differences in correlation structure, receiver-reported accuracy systematically underestimated empirical error in all environments. Median DRMS exceeded reported accuracy by factors ranging from approximately 2.6 (forest edge/tree-adjacent) to 8.0 (forest interior/building-adjacent). Dispersion inflation under severe obstruction was not proportionally reflected in reported accuracy metrics.
Dynamic measurements across 13 operational environment classes further demonstrated horizontal degradation relative to open-sky conditions and consistent vertical error inflation. Dynamic horizontal receiver-reported accuracy ranged from 273 mm in unobstructed locations to 758 mm in forested environments with vertical obstructions, while vertical accuracy varied between 397 mm and 1333 mm across the same conditions. These values highlight the impact of vegetation, vertical structures, and terrain slope on the GNSS solution's reported accuracy, and suggest that even when absolute positioning errors differ, reported precision can serve as a relative indicator of environmental complexity affecting receiver performance.
These findings indicate that receiver-reported GNSS accuracy exhibits environment-dependent predictive validity but consistently underestimates true positional error magnitude in obstructed forest conditions. Reported accuracy metrics should therefore be interpreted cautiously and not as absolute values. Given the generally weak or negligible linear correlations in highly obstructed environments, these metrics cannot be reliably corrected or rescaled to match true error; simple multiplicative adjustments will not produce accurate positioning estimates, they may however find a use as relative or qualitative metrics.
| Keywords | forestry; mechanization; gnss; accuracy |
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