# Intrinsic calibration models

Every camera is individually calibrated in production. We use two different models depending on the field of view of the camera.

## Fisheye model

This applies to the wide opening angle (O3R225) cameras. For these cameras, we use the fisheye distortion model as described below.

### For unprojection: intrinisc calibration model

This model is used for converting pixel positions to 3D vectors. It corresponds to `modelID=2`

. The following formulas show how to apply the model:

Where

are the input coordinates as integer numbers, in pixels,

is the resulting 3D direction vector in the optical coordinate system,

are the model parameters obtained from the

`modelParameters`

array.

### For projection: inverse intrinsic calibration model

This model is used for converting directions given as 3D vectors to pixel position. This corresponds to `modelID=3`

. The following formulas show how to apply the model:

Where

is the input direction vector in the optical coordinate system,

are the resulting image coordinates (the upper left pixel has coordinates ),

are the model parameters obtained from the

`modelParameters`

array.

## Bouguet model

### For unprojection: intrinisc calibration model

This model is used for converting pixel positions to 3D vectors. It corresponds to `modelID=0`

. The following formulas show how to apply the model:

Where

are the input coordinates are integer numbers, in pixels,

is the resulting 3D direction vector in the optical coordinate system,

are the model parameters obtained from the

`modelParameters`

array.

### For projection: inverse intrinsic calibration model

This model is used for converting directions given as 3D vectors to pixel position. This corresponds to `modelID=1`

. The following formulas show how to apply the model:

Where

is the input direction vector in the optical coordinate system,

are the resulting image coordinates (the upper left pixel has coordinates ),

are the model parameters obtained from the

`modelParameters`

array.