# cameraPoseToExtrinsics

(Not recommended) Convert camera pose to extrinsics

`cameraPoseToExtrinsics` is not recommended. Use the `pose2extr` function instead. For more information, see Version History.

## Syntax

``tform = cameraPoseToExtrinsics(cameraPose)``
``````[rotationMatrix,translationVector] = cameraPoseToExtrinsics(orientation,location)``````

## Description

````tform = cameraPoseToExtrinsics(cameraPose)` returns a `rigid3d` object that contains the transformation from world coordinates to camera coordinates. `cameraPose` is the orientation and location of the camera in world coordinates, specified as a `rigid3d` object.```
``````[rotationMatrix,translationVector] = cameraPoseToExtrinsics(orientation,location)``` returns the camera extrinsics, `rotationMatrix` and `translationVector`, which represent the coordinate system transformation from world coordinates to camera coordinates. The inputs, `orientation` and `location`, represent the 3-D camera pose in the world coordinates.```

example

## Examples

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Create the 3-D orientation matrix and the location vector.

```orientation = eye(3); location = [0 0 10];```

Compute the rotation matrix and translation vector to transform points from world coordinates to camera coordinates.

`[rotationMatrix,translationVector] = cameraPoseToExtrinsics(orientation,location)`
```rotationMatrix = 3×3 1 0 0 0 1 0 0 0 1 ```
```translationVector = 1×3 0 0 -10 ```

Compute the transformation from world coordinates to camera coordinates as a rigid 3-D object.

```cameraPose = rigid3d(orientation,location); tform = cameraPoseToExtrinsics(cameraPose)```
```tform = rigid3d with properties: Rotation: [3x3 double] Translation: [0 0 -10] ```

## Input Arguments

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Orientation and location of the camera in world coordinates, specified as a `rigid3d` object.

3-D orientation of the camera in world coordinates, specified as a 3-by-3 matrix. The `orientation` and `location` inputs must be the same data type.

Data Types: `double` | `single`

3-D location of the camera in world coordinates, specified as a three-element vector. The `orientation` and `location` inputs must be the same data type.

Data Types: `double` | `single`

## Output Arguments

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Transformation from world coordinates to camera coordinates, returned as a `rigid3d` object. The transformation allows you to transform points from the world coordinate system to the camera coordinate system. `tform` is computed as:

```tform.Rotation = cameraPose.Rotation' tform.Translation = -cameraPose.Translation * cameraPose.Rotation'```

3-D rotation, returned as a 3-by-3 matrix. The rotation matrix, together with the translation vector allows you to transform points from the world coordinate system to the camera coordinate system.

The relationship between the rotation matrix and the input orientation matrix is:

 `rotationMatrix` = `orientation`'

3-D translation, returned as a 1-by-3 vector. The translation vector together with the rotation matrix, enables you to transform points from the world coordinate system to the camera coordinate system.

The relationship between the translation vector and the input orientation matrix is :

 `translationVector` = –`location`*`orientation`'

## Version History

Introduced in R2016b

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### R2022b: Not recommended

Starting in R2022b, most Computer Vision Toolbox™ functions create and perform geometric transformations using the premultiply convention. However, the `cameraPoseToExtrinsics` function uses the postmultiply convention. Although there are no plans to remove `cameraPoseToExtrinsics` at this time, you can streamline your geometric transformation workflows by switching to the `pose2extr` function, which supports the premultiply convention. For more information, see Migrate Geometric Transformations to Premultiply Convention.

• Change instances of the function name `cameraPoseToExtrinsics` to `pose2extr`.

• Specify the camera pose as a `rigidtform3d` object using the `cameraPose` argument. `pose2extr` does not support specifying the camera pose using the `orientation` and `translation` input arguments. Note that you create the `rigidtform3d` object using the transpose of `orientation` or the transpose of the transformation matrix in the `T` property of `tform`.

Discouraged UsageRecommended Replacement

This example specifies the camera pose as a rotation matrix `orientation` in the premultiply convention and a translation vector `location`, then converts the camera pose to extrinsics using the `cameraPoseToExtrinsics` function, using the transpose of `orientation`.

```orientation = eye(3); location = [0 0 10]; [rotationMatrixOld,translationVector] = cameraPoseToExtrinsics( ... orientation',location)```

This example specifies the camera pose as a `rigidtform3d` object, then converts the camera pose to extrinsics using the `pose2extr` function.

```orientation = eye(3); location = [0 0 10]; cameraPose = rigidtform3d(orientation,location); extrinsics = pose2extr(cameraPose);```

If you need to obtain a rotation matrix and translation vector, then you can query properties of `extrinsics`.

```rotationMatrix = extrinsics.R; translationVector = extrinsics.Translation;```

If you want the rotation matrix in the postmultiply convention, take the transpose of `extrinsics.R`.

`rotationMatrixOld = extrinsics.R';`

This example specifies a camera pose as a `rigid3d` object using the transpose of the geometric transformation matrix `A` in the premultiply convention, then converts the camera pose to extrinsics using the `cameraPoseToExtrinsics` function.

```A = [1 0 0 0; 0 1 0 0; 0 0 1 10; 0 0 0 1]; cameraPoseOld = rigid3d(A'); extrinsicsOld = cameraPoseToExtrinsics(cameraPoseOld);```

This example specifies the camera pose as a `rigidtform3d` object using the geometric transformation matrix `A`, then converts the camera pose to extrinsics using the `pose2extr` function.

```A = [1 0 0 0; 0 1 0 0; 0 0 1 10; 0 0 0 1]; cameraPose = rigidtform3d(A); extrinsics = pose2extr(cameraPose);```

If instead you start with an existing `rigid3d` object `cameraPoseOld`, then you can get the geometric transformation matrix in the postmultiply convention by querying the property `T` of `cameraPoseOld`.

```T = cameraPoseOld.T; cameraPose = rigidtform3d(T'); extrinsics = pose2extr(cameraPose);```