# lla2enu

Transform geodetic coordinates to local east-north-up coordinates

## Syntax

``xyzENU = lla2enu(lla,lla0,method)``

## Description

example

````xyzENU = lla2enu(lla,lla0,method)` transforms the geodetic coordinates `lla` to local east-north-up (ENU) Cartesian coordinates `xyzENU`. Specify the origin of the local ENU system as the geodetic coordinates `lla0`. NoteThe latitude and longitude values in the geodetic coordinate system use the World Geodetic System of 1984 (WGS84) standard.Specify altitude as height in meters above the WGS84 reference ellipsoid. ```

## Examples

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Specify the geodetic coordinates of the local origin in Zermatt, Switzerland.

`lla0 = [46.017 7.750 1673]; % [lat0 lon0 alt0]`

Specify the geodetic coordinates of a point of interest. In this case, the point of interest is the Matterhorn.

`lla = [45.976 7.658 4531]; % [lat lon alt]`

Transform the geodetic coordinates to local ENU coordinates using flat earth approximation.

`xyzENU = lla2enu(lla,lla0,'flat')`
```xyzENU = 1×3 103 × -7.1244 -4.5572 2.8580 ```

## Input Arguments

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Geodetic coordinates, specified as a three-element row vector or an n-by-3 matrix. n is the number of points to transform. Specify each point in the form ```[lat lon alt]```. lat and lon specify the latitude and longitude respectively in degrees. alt specifies the altitude in meters.

Example: `[45.976 7.658 4531]`

Data Types: `double`

Origin of the local ENU system in the geodetic coordinates, specified as a three-element row vector or an n-by-3 matrix. n is the number of origin points. Specify each point in the form ```[lat0 lon0 alt0]```. lat0 and lon0 specify the latitude and longitude of the origin, respectively, in degrees. alt0 specifies the altitude of the origin in meters.

Example: `[46.017 7.750 1673]`

Data Types: `double`

Transformation method, specified as `'flat'` or `'ellipsoid'`. This argument specifies whether the function assumes the planet is flat or ellipsoidal.

The flat Earth transformation method has these limitations:

• Assumes that the flight path and bank angle are zero.

• Assumes that the flat Earth z-axis is normal to the Earth at only the initial geodetic latitude and longitude. This method has higher accuracy over small distances from the initial geodetic latitude and longitude, and closer to the equator. The method calculates a longitude with higher accuracy when the variation in latitude is smaller.

• Latitude values of +90 and -90 degree may return unexpected values because of singularity at the poles.

Data Types: `char` | `string`

## Output Arguments

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Local ENU Cartesian coordinates, returned as a three-element row vector or an n-by-3 matrix. n is the number of transformed points. Each point is in the form ```[xEast yNorth zUp]```. xEast, yNorth, and zUp are the respective x-, y-, and z-coordinates, in meters, of the point in the local ENU system.

Data Types: `double`