# Documentation

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# mfwdtran

Project geographic features to map coordinates

## Syntax

`[x,y] = mfwdtran(lat,lon)[x,y,z] = mfwdtran(lat,lon,alt)[...] = mfwdtran(mstruct,...)`

## Description

`[x,y] = mfwdtran(lat,lon)` applies the forward transformation defined by the map projection in the current map axes. You can use this function to convert point locations and line and polygon vertices given in latitudes and longitudes to a planar, projected map coordinate system.

`[x,y,z] = mfwdtran(lat,lon,alt)` applies the forward projection to 3-D input, resulting in 3-D output. If the input `alt` is empty or omitted, then `alt` = 0 is assumed.

`[...] = mfwdtran(mstruct,...)` requires a valid map projection structure as the first argument. In this case, no map axes is needed.

## Examples

collapse all

Get geographic location data for District of Columbia.

```dc = shaperead('usastatelo', 'UseGeoCoords', true,... 'Selector',{@(name) strcmpi(name,'District of Columbia'),... 'Name'}); lat = [dc.Lat]'; lon = [dc.Lon]'; [lat lon] ```
```ans = 38.9000 -77.0700 38.9500 -77.1200 39.0000 -77.0300 38.9000 -76.9000 38.7800 -77.0300 38.8000 -77.0200 38.8700 -77.0200 38.9000 -77.0700 38.9000 -77.0700 NaN NaN ```

Obtain the UTM zone for this point.

```dczone = utmzone(mean(lat,'omitnan'),mean(lon,'omitnan')) ```
```dczone = 18S ```

Set up the UTM coordinate system based on this information.

```utmstruct = defaultm('utm'); utmstruct.zone = dczone; utmstruct.geoid = wgs84Ellipsoid; utmstruct = defaultm(utmstruct) ```
```utmstruct = struct with fields: mapprojection: 'utm' zone: '18S' angleunits: 'degrees' aspect: 'normal' falsenorthing: 0 falseeasting: 500000 fixedorient: [] geoid: [1×1 referenceEllipsoid] maplatlimit: [32 40] maplonlimit: [-78 -72] mapparallels: [] nparallels: 0 origin: [0 -75 0] scalefactor: 0.9996 trimlat: [-80 84] trimlon: [-180 180] frame: 'off' ffill: 100 fedgecolor: [0.1500 0.1500 0.1500] ffacecolor: 'none' flatlimit: [32 40] flinewidth: 2 flonlimit: [-3 3] grid: 'off' galtitude: Inf gcolor: [0.1500 0.1500 0.1500] glinestyle: ':' glinewidth: 0.5000 mlineexception: [] mlinefill: 100 mlinelimit: [] mlinelocation: 1 mlinevisible: 'on' plineexception: [] plinefill: 100 plinelimit: [] plinelocation: 1 plinevisible: 'on' fontangle: 'normal' fontcolor: [0.1500 0.1500 0.1500] fontname: 'Helvetica' fontsize: 10 fontunits: 'points' fontweight: 'normal' labelformat: 'compass' labelrotation: 'off' labelunits: 'degrees' meridianlabel: 'off' mlabellocation: 1 mlabelparallel: 40 mlabelround: 0 parallellabel: 'off' plabellocation: 1 plabelmeridian: -78 plabelround: 0 ```

Project the District of Columbia data from geographic coordinates into map coordinates for UTM zone 18S.

```[x,y] = mfwdtran(utmstruct,lat,lon) ```
```x = 1.0e+05 * 3.2049 3.1629 3.2421 3.3524 3.2367 3.2459 3.2476 3.2049 3.2049 NaN y = 1.0e+06 * 4.3077 4.3134 4.3187 4.3074 4.2943 4.2965 4.3043 4.3077 4.3077 NaN ```