價格：免費
更新日期：2019-06-05
檔案大小：5.6M
目前版本：2.0
版本需求：Android 8.0 以上版本
官方網站：mailto:newton.moura.junior@gmail.com
To a more actual geoid model: https://play.google.com/store/apps/details?id=tools.gnss.highprecisiongeoid
The principal aim of this app is calculate, being offline, a high precision geoid height undulation (N) to be used in field by engineers, topographers and cartographers who are using a GNSS receiver with high precision coordinates too. The GPS from your phone doesn't give to you a high precision ellipsoidal height so it isn't a good idea use it to obtain the ellipsoidal height (h).
Undulation of the geoid (N) is the mathematical process of determining the height in meters , positive if above or negative if below, relative from the geoid to a ellipsoid provided by the GNSS system. The height given by you GNSS receiver it's referred to a specific GNSS ellipsoid like WGS84 and is called ellipsoidal height (h).
The best approximation for your topographic height it's called orthometric height(H) obtained by the formula: H = h - N.
This app calculate Geoid Undulation using EGM96 using Associated Legendre Functions. It was based in https://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/f477.f. So it do not use interpolation anymore.
The original FORTRAN code was rewtitten in Kotlin.
https://github.com/newton-jose/egm96/blob/master/egm96.kts
This can be used as free version of more precision EGM2008 2.5'x2.5' grid found at https://play.google.com/store/apps/details?id=tools.gnss.highprecisiongeoid
It's works offline so you don't need be connected to use it.
It's only needed be connected to download it from play store.