# mapoutline

Compute outline of georeferenced image or data grid

## Syntax

```[x,y] = mapoutline(R,height,width) [x,y] = mapoutline(R, sizea) [x,y] = mapoutline(info) [x,y] = mapoutline(...,'close') [lon,lat] = mapoutline(R,...) outline = mapoutline(...) ```

## Description

`[x,y] = mapoutline(R,height,width)` computes the outline of a georeferenced image or regular gridded data set in map coordinates. `R` is either a 3-by-2 referencing matrix defining a 2-dimensional affine transformation from intrinsic pixel coordinates to map coordinates, or a `MapCellsReference` or `MapPostingsReference` object. `height` and `width` are the image dimensions. `x` and `y` are 4-by-1 column vectors containing the map coordinates of the outer corners of the corner pixels, in the following order:

`(1,1), (height,1), (height, width), (1, width)`.

`[x,y] = mapoutline(R, sizea)` accepts ```sizea = [height, width, ...]``` instead of `height` and `width`.

`[x,y] = mapoutline(info)` accepts a scalar structure array with the fields

 `'RefMatrix'` 3-by-2 referencing matrix `'Height'` Scalar number `'Width'` Scalar number

`[x,y] = mapoutline(...,'close')` returns `x` and `y` as 5-by-1 vectors, appending the coordinates of the first of the four corners to the end.

`[lon,lat] = mapoutline(R,...)`, where `R` georeferences pixels to longitude and latitude rather than map coordinates, returns the outline in geographic coordinates. Longitude must precede latitude in the output argument list.

`outline = mapoutline(...)` returns the corner coordinates in a 4-by-2 or 5-by-2 array.

## Examples

Draw a red outline delineating the Boston GeoTIFF image, which is referenced to the Massachusetts Mainland State Plane coordinate system with units of survey feet.

```figure info = georasterinfo('boston.tif'); R = info.RasterReference; [x,y] = mapoutline(R,R.RasterSize,'close'); hold on plot(x,y,'r') xlabel('MA Mainland State Plane easting, survey feet') ylabel('MA Mainland State Plane northing, survey feet')```
Draw a black outline delineating a TIFF image of Concord, Massachusetts, while lies roughly 25 km north west of Boston. Convert world file units to survey feet from meters to be consistent with the Boston image.
```info = imfinfo('concord_ortho_w.tif'); R = worldfileread('concord_ortho_w.tfw','planar', ... [info.Height info.Width]); [x,y] = mapoutline(R, info.Height, info.Width, 'close'); x = x * unitsratio('sf','meter'); y = y * unitsratio('sf','meter'); plot(x,y,'k')```

### Objects

Introduced before R2006a

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