GSWA Widgiemooltha South Elevation Line Data

Digital Elevation Model data record the terrain height variations from the processed point-located data recorded on an airborne geophysical survey.� The aircraft altimeter data records the height of the aircraft above the ground and the aircraft GPS records the height of the aircraft above the ellipsoid.� Subtracting the two values enables the height of the terrain beneath the aircraft relative to the ellipsoid to be calculated.� This ellipsoidal terrain height is corrected for the variation between the ellipsoid and the geoid (the n-value correction) to produce terrain heights relative to sea level.

数字高程模型（Digital Elevation Model）数据由航空地球物理测量中记录的点定位数据经处理后生成，用于记录地形高度变化。飞机高度计数据记录飞机距地面的高度，而飞机GPS数据记录飞机相对于椭球体（ellipsoid）的高度。对这两个值进行相减运算，即可计算出飞机下方地形相对于椭球体的高度。该椭球体地形高度需经过椭球体与大地水准面（geoid）之间差异的校正（即n值校正，n-value correction），以得到相对于海平面的地形高度。