src/dw/rig/doc_public/mainsection.md

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# Copyright (c) 2019-2020 NVIDIA CORPORATION.  All rights reserved.

@page rig_mainsection Rig Configuration

## About This Module

The car is considered a rig with several rigidly-attached sensors. The dimensions of the car and the positions and orientations of these sensors relative to the car are important to NVIDIA<sup>&reg;</sup> DriveWorks accuracy. The particular properties of a rig, which are represented by a rig configuration, are measured and estimated by a calibration process.

The rig configuration module allows reading and enumerating of these pre-calibrated properties. The module obtains the rig configuration from a rig configuration file generated by the DriveWorks calibration tool. For more information, see DriveWorks Calibration Tool Application Note in the doc/pdf/calibration folder of this release.
Rig configuration files can also be serialized by the module.

An example of the JSON structure of a rig configuration file is given below.
```
{
   "rig": {
      "sensors": [
         {...}, ...
      ],
      "vehicle": {
         "valid" : true,
         "value" : {
            "axleFront": {...},
            "axleRear": {...},
            "body": {...},
            "actuation": {...},
            "suspension": {...},
            "hasCabin": false,
            "numTrailers": 0,
          }
      }
   },
   "version" : 7
}
```
A rig configuration object (`::dwRigHandle_t`) can be initialized either from a file or directly from string (see `dwRig_initializeFromFile()`). Once the rig configuration is loaded successfully, individual properties of the rig and it's sensors can be queried. Vehicle properties are represented by the dwVehicle struct (see `dwRig_getVehicle()`). Generic sensor properties can be obtained through the function `dwRig_getSensorXXX`. Some sensors may have more specific properties, which can be obtained using dedicated functions, like the calibrated camera model (for example see `dwRig_getPinholeCameraConfig()`).

### Camera Rig and Camera Models

A number of modules use a camera-only rig that contains only rigidly-attached calibrated cameras (`::dwCameraModelHandle_t`). This camera rig is a subset of the generic rig. It can be initialized independently or directly from a generic rig configuration (see `dwRig_initializeFromFile()`).

The supported calibrated camera models are pinhole, OCam, and FTheta. Their calibration parameters are specified with the `dwPinholeCameraConfig`, `::dwOCamCameraConfig`, and `::dwFThetaCameraConfig` structs, respectively. For each of these camera models, DriveWorks provides generic `dwCameraModel_pixel2Ray()` and `dwCameraModel_ray2Pixel()` functions to transform a point from image space to camera space and vice versa (see @ref cameramodel_mainsection for details).

## Relevant Tutorials

- @ref rigconfiguration_usecase0
- @ref rigconfiguration_usecase1

## APIs

- @ref rig_configuration_group
- @ref cameramodel_group