A file extension is the set of three or four characters at the end of a filename; in this case, .obj. File extensions tell you what type of file it is, and tell Windows what programs can open it. Windows often associates a default program to each file extension, so that when you double-click the file, the program launches automatically.
A sensory threshold is the level of strength a stimulus must reach to be detected. Psychologists study sensory thresholds to learn how humans and animals process sensory information.An absolute threshold is the lowest level of strength necessary for detection.For example, when sounds are just loud enough to hear (but no louder), they occur at the absolute threshold.Absolute thresholds vary according to sensory adaptation (diminished sensitivity to stimulus after prolonged exposure).Animals often have different absolute thresholds than people. The differential threshold is the point of lowest intensity at which one can tell that a stimulus has strengthened.n absolute threshold is the lowest level of strength necessary for detection. For example, when sounds are just loud enough to hear (but no louder), they occur at the absolute threshold. Absolute thresholds vary according to sensory adaptation (diminished sensitivity to stimulus after prolonged exposure).
Such definitions typically define a forest as an area growing trees above some threshold. These thresholds are typically the number of trees per area (density), the area of ground under the tree canopy (canopy cover) or the section of land that is occupied by the cross-section of tree trunks (basal area).