如何从平均海平面计算上面的高度 [英] How to calculate the altitude above from mean sea level

问题描述

我试图找到如何获得高于平均海平面高度。 此时，它返回高度从椭球。 所以，任何人都知道的公式或计算改变高度值 从椭球从平均海平面高度值。

I tried to find how to get the altitude above the mean sea level. At this time, it returns altitude from the ellipsoid. So, anyone knows the formula or calculation to change the altitude value from ellipsoid to the altitude value from mean sea level.

感谢您所有帮助

推荐答案

至于你提到的GPS返回海拔高度为从WGS84参考椭球的偏移，但大多数人希望看到的平均海平面（MSL），和两个经常不同意。的方式，这是最经常做的是通过查找三角洲一个表，并采用了基于全球定位系统的高度和增量表中的计算MSL。

As you mentioned, GPS returns the altitude as an offset from the WGS84 reference ellipsoid, but most people want to see mean sea level (MSL), and the two frequently don't agree. The way this is most frequently done is by looking up the delta in a table and using that to compute MSL based on the height from GPS and the delta in the table.

有一些Java code在这里：<一href="http://worldwind31.arc.nasa.gov/svn/trunk/WorldWind/src/gov/nasa/worldwind/util/EGM96.java">http://worldwind31.arc.nasa.gov/svn/trunk/WorldWind/src/gov/nasa/worldwind/util/EGM96.java.它从世界风使用的其他功能都没有那么复杂，那么你很可能大部分的code未经修改的，其余的，你可以调整，如果你工作在Java和他们的执照满足您的需求。

There's some java code here: http://worldwind31.arc.nasa.gov/svn/trunk/WorldWind/src/gov/nasa/worldwind/util/EGM96.java. The other functions that it uses from Worldwind aren't that complicated, so you could probably use most of the code unmodified, and the rest you could adapt if you're working in Java and their license meets your needs.

它使用临时股东大会96数据集（信息链接这里如果你有兴趣 - 不是绝对必要的，虽然），你可以在这里下载：<一href="http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/binary/binarygeoid.html">http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/binary/binarygeoid.html.你会想WW15MGH.DAC文件。这是一个二进制文件满了16位有符号整数。您可以使用Java的例子向您展示如何访问数据的文件中。他们还提供了一个Fortran例如，如果那是你的事。 ： - ）

It uses information from the EGM 96 data set (link here if you're interested -- not strictly necessary though), which you can download here: http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/binary/binarygeoid.html. You will want the WW15MGH.DAC file. It's a binary file full of 16-bit signed integers. You can use the Java example to show you how to access the data in the file. They also provide a Fortran example if that's your thing. :-)

下面是从他们的自述文件中的信息。

Here's the information on the file from their readme.

数据说明了15分钟全球的二进制大地水准面文件：

Data Description for 15 minute worldwide binary geoid height file:

---- FILE：WW15MGH.DAC

---- FILE: WW15MGH.DAC

的文件的总大小是2076480字节。创建这个文件   使用INTEGER * 2数据类型格式，它是一个未格式化的直接访问   文件。对文件中的数据被安排在记录从北到南。   有721条记录上的文件开始记录1 90 N的   在文件的最后记录是在北纬90 S.对于每一个记录，有   是安排经度由西1,440 15弧分的大地水准面的高度   东起于本初子午线（0 E）和西部结束15弧分   的本初子午线（359.75 E）。在文件中，大地水准面是单位   以厘米。虽然通过检索的文件，除整数* 2的值   100，这将产生一个大地水准面米。

The total size of the file is 2,076,480 bytes. This file was created using an INTEGER*2 data type format and is an unformatted direct access file. The data on the file is arranged in records from north to south. There are 721 records on the file starting with record 1 at 90 N. The last record on the file is at latitude 90 S. For each record, there are 1,440 15 arc-minute geoid heights arranged by longitude from west to east starting at the Prime Meridian (0 E) and ending 15 arc-minutes west of the Prime Meridian (359.75 E). On file, the geoid heights are in units of centimeters. While retrieving the Integer*2 values on file, divide by 100 and this will produce a geoid height in meters.

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