Table 1. Quantified obstacle properties, sourced from literature, and obstacle characteristics based on Campbell and Wynne’s (2011) classification of objects. If the obstacle possesses the stated characteristic, a Y (Yes) is marked. An N (No) marks if the obstacle does not possess such characteristic. | |||||
Characteristic | Stone | Stump | Root | Slash | Soil |
Density [kg·m–3] | 2500–3200a | 440–670b | 301–499c | 844–883d | 1400–2050e |
Tensile modulus [109 Pa] | 40–68f | 8.1–16.2b | 8.1–16.2b | 8.1–16.2b | 4.8∙10–4–0.2g |
Thermal conductivity [W·m–1·K–1] | 2.51–3.97f | 0.12–0.22f | 0.12–0.22f | 0.12–0.22f | 0.17–2.2f |
Reflectance [%] (λ∈[300m–9 2500m–9])* | 5–80h | 10–65i | - | 3–85i, k | 0–55h, i |
Moisture content [fresh weight %] | ~0 | 15–64d, j | 15–55j | 29–56d, l | 0–100 |
Distinguishable tone m | Y | Y | N | Y | Y |
Distinguishable texture (roughness) m | Y | Y | Y | Y | Y |
Casts a shadow m | Y/N | Y | N | Y/N | N |
Forms a distinguishable pattern m | N | Y/N | N | N | N |
Other objects or features is associated to the obstacle m | Y | Y | Y | Y | Y |
Distinguishable shape m | Y | Y | Y | Y | N |
Is found on specific topological sites m | N | Y/N | Y | N | N |
Can be moved with force exerted during mounding or disc trenching | Y/N | N** | Y/N | Y | Y |
Degradation over a forest rotational period | N | Y | Y | Y | N |
Exists above ground | Y | Y | Y/N | Y | N |
Exists below ground | Y | N | Y | N | Y |
a Elming (1980); b Tsoumis (1991), Doran (1992), Nordling and Österman (2006); c Kalliokoski (2008); d Kärkkäinen (1976); e Parasnis (1971), Parasnis and Dattatrai (1997), Cardarelli (2008); f Saarman (1992), Cardarelli (2008); g U.S. Army… (1990); h Bowker et al. (1985); i Lang et al. (2002); j Laurila and Lauhanen (2010); k Williams (1991); l Nurmi (1999); m Campbell and Wynne (2011) * λ = wavelength of radiated light ** Applies for stumps > 100 mm in diameter |
Fig. 1. Flowchart of the activities conducted by a computer-aided system using object identification for avoidance or targeting purposes.