Kurt Angle | gauge | Angle Shades | angle | Small Angle Shades | An Angle | American wire gauge | Sharron Angle | Indian gauge | Ultra wide angle lens | Small-angle X-ray scattering | Small-angle scattering | Nuclear density gauge | Edward Angle | Durango and Silverton Narrow Gauge Railroad | Degree (angle) | Apsheronsk narrow-gauge railway | Angle Township, Lake of the Woods County, Minnesota | Angle Township | Angle of incidence | Alexander Gauge | UK National Tide Gauge Network | The Zenith Angle | Solid angle | solid angle | Slip angle | Site of Krasnokholmsky Bridges, 1853, from ''Khotev's Atlas''. Note the channel separating Red Hills (triangular island) and the angle of bridge across Moskva River | OO gauge | Northwest Angle | Nevada County Narrow Gauge Railroad |
It happens when a tree cannot be easily determined as in or out when using a prism or angle gauge.