advancedfunctions/lightsourceperception/docs/lightsourceperception_usecase1.md

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

@page lightsourceperception_usecase1 LigthSourceDetector Workflow

## Initialization

The LightSourceDetector module creates handle of type `dwLightSourceDetectorHandle_t`. This handle is owned by the application and must be released by the application when not needed anymore.

An instance of type `dwLightSourceDetectorParams` encodes parameters (currently only perception ROI) and encapsulates a handle to LightSourceNet (of type `dwLightSourceNetHandle_t`) that configures the LightSourceDetector module.

To initialize a pointer to a `dwLightSourceDetectorHandle_t` instance with an initialized LightSourceNet handle and default parameter values:

```{.cpp}
dwStatus dwLightSourceDetector_initialize(dwLightSourceDetectorHandle_t* obj,
                                         dwLightSourceNetHandle_t ligthSourceNet,
                                         dwContextHandle_t ctx);
```

An example code snippet to initialize required modules with default values:

```{.cpp}
dwLightSourceNetHandle_t m_lightSourceNet = DW_NULL_HANDLE;
dwLightSourceNetParams m_lightSourceNetParams{};
dwLightSourceDetectorHandle_t m_lightSourceDetector = DW_NULL_HANDLE;

// Initialize LightSourceNet
CHECK_DW_ERROR(dwLightSourceNet_initDefaultParams(&m_lightSourceNetParams));
CHECK_DW_ERROR(dwLightSourceNet_initialize(&m_lightSourceNet, &m_lightSourceNetParams, m_sdk));

// dwLightSourceDetector_initialize
CHECK_DW_ERROR(dwLightSourceDetector_initialize(&m_lightSourceDetector, m_lightSourceNet, m_sdk));
```

where `m_sdk` is an initialized instance of `dwContextHandle_t`.

## Processing

With initialized handle to the LightSourceDetector module, the following functions can be used to perform inference on an image and retrieve the processed output, which indicate binary ON/OFF high beam signal:

```{.cpp}
typedef struct
{
    /// High beam ON/OFF binary flag.
    bool flag;

} dwLightSourceDetectorAutoBeamStatus;

DW_API_PUBLIC
dwStatus dwLightSourceDetector_bindInput(const dwImageCUDA* imageRGB,
                                         const dwImageCUDA* imageBayer,
                                         dwLightSourceDetectorHandle_t obj);

DW_API_PUBLIC
dwStatus dwLightSourceDetector_bindOutputAutoBeamStatus(dwLightSourceDetectorAutoBeamStatus* output,
                                                        dwLightSourceDetectorHandle_t obj);

DW_API_PUBLIC
dwStatus dwLightSourceDetector_bindOutputDetectorMask(dwLightSourceDetectorMask* output,
                                                      dwLightSourceDetectorHandle_t obj);

typedef enum {
    /// Input image is preprocessed on GPU side with certain predefined transformations
    /// in order to have the right properties required by DNN inference.
    DW_LSP_DETECTOR_STAGE_GPU_PREPROCESS = 0,

    /// DNN inference is run on prepared image.
    DW_LSP_DETECTOR_STAGE_GPU_INFERENCE = 1,

    /// DNN inference is run on prepared image.
    DW_LSP_DETECTOR_STAGE_GPU_POSTPROCESS = 2,

    /// After inference CPU runs post processing.
    DW_LSP_DETECTOR_STAGE_CPU_POSTPROCESS = 3,

} dwLightSourceDetectorStage;

DW_API_PUBLIC
dwStatus dwLightSourceDetector_process(dwLightSourceDetectorStage stage,
                                       dwLightSourceDetectorHandle_t obj);

```

## Release

The following functions can be used to reset or release the initialized module handles whenever necessary:

```{.cpp}
dwStatus dwLightSourceDetector_release(dwLightSourceDetectorHandle_t obj);
```

For usage of a sample application, please refer to @ref dwx_lightsourceperception_sample.

## Additional Information

See @ref lightsourcenet_mainsection for information on DNN used in this perception module (LightSourceNet).