ROI Tracker

ROI Tracker is one of the main features of the Media Vision API. This API allows users to obtain the proper ROI coordinates that users want to track in an image. For example, when an image and ROI coordinates are provided as input to this API, the Media Vision framework will process the given image and ROI coordinates from the decoded image data and will provide ROI coordinates within the given image.

Prerequisites

To enable your application to use the media vision ROI Tracker functionality, follow these steps:

  1. To use the functions and data types of the Media Vision ROI Tracker API (in mobile and wearable applications), include the <mv_roi_tracker.h> header file in your application:

    #include <mv_roi_tracker.h>

  2. Create a callback function to store the returned ROI data.

    To obtain ROI coordinates, create a callback function:

    void _tracked_cb(mv_source_h source, mv_rectangle_s roi, void *user_data)
{
   printf("In callback: roi.x y width height : %d %d %d %d\n", roi.point.x, roi.point.y, roi.width, roi.height);
}

Track object

To track the ROI coordinates of an image, follow these steps:

  1. Create the source and engine configuration handles:

    int error_code = 0;

error_code = mv_create_source(&mv_source);
if (error_code != MEDIA_VISION_ERROR_NONE)
    dlog_print(DLOG_ERROR, LOG_TAG, "error code = %d", error_code);

error_code = mv_create_engine_config(&imagedata.g_engine_config);
if (error_code != MEDIA_VISION_ERROR_NONE)
    dlog_print(DLOG_ERROR, LOG_TAG, "error code= %d", error_code);

  2. Decode the image file and fill the mv_source handle with the decoded raw data.

    In the following example, sample.jpg is the image to be tracked, and it is in the <OwnDataPath>. The <OwnDataPath> refers to your own data path. It uses ImageHelper to fill mv_source:

    mv_source_h mv_source = NULL;

ret = mv_create_source(&mv_source);
ASSERT_EQ(ret, MEDIA_VISION_ERROR_NONE);

ret = ImageHelper::loadImageToSource(image_path.c_str(), mv_source);
ASSERT_EQ(ret, MEDIA_VISION_ERROR_NONE);

  3. To track the sample.jpg image, create a handle media vision ROI Tracker handle:

    error_code = mv_roi_tracker_create(&handle);
if (error_code != MEDIA_VISION_ERROR_NONE)
    dlog_print(DLOG_ERROR, LOG_TAG, "error code = %d", error_code);

  4. Set tracker mode for running the tracker. The default mode is MV_ROI_TRACKER_TYPE_BALANCE:

    int error_code = 0;
error_code = mv_engine_config_set_int_attribute(engine_cfg, MV_ROI_TRACKER_TYPE, (int) MV_ROI_TRACKER_TYPE_BALANCE);
if (ret != MEDIA_VISION_ERROR_NONE)
	dlog_print(DLOG_ERROR, LOG_TAG, "error code= %d", error_code);

    For more information on the configuration attributes, such as MV_ROI_TRACKER_TYPE_BALANCE, see Media Vision ROI Tracker API (in mobile and wearable applications).

  5. Use mv_roi_tracker_configure() to configure handle ROI Tracker handle with config:

    error_code = ret = mv_roi_tracker_configure(handle, config);
if (error_code != MEDIA_VISION_ERROR_NONE)
    dlog_print(DLOG_ERROR, LOG_TAG, "error code = %d", error_code);

  6. Use mv_roi_tracker_prepare() to prepare ROI tracking. This uses the coordinates x, y, width, and height, that will be used for ROI tracking within the image:

    int x, y, width, height;
error_code = mv_roi_tracker_prepare(handle, x, y, width, height);
if (error_code != MEDIA_VISION_ERROR_NONE)
    dlog_print(DLOG_ERROR, LOG_TAG, "error code = %d", error_code);

  7. Use mv_roi_tracker_perform() to track the image continuously:

    error_code = mv_roi_tracker_perform(handle, mv_source, _tracked_cb, NULL);
if (error_code != MEDIA_VISION_ERROR_NONE)
    dlog_print(DLOG_ERROR, LOG_TAG, "error code = %d", error_code);

    mv_roi_tracker_perform() invokes _tracked_cb() callback. The following callback example prints the tracked coordinates:

    static 
void _tracked_cb(mv_source_h source, mv_rectangle_s roi, void *user_data)
{
    printf("In callback: roi.x y width height : %d %d %d %d\n", roi.point.x, roi.point.y, roi.width, roi.height);
}

  8. After the ROI tracking is complete, destroy the source, engine configuration, and the ROI Tracker handles using mv_destroy_source(), mv_destroy_engine_config(), and mv_roi_tracker_destroy():

    error_code = mv_destroy_source(mv_source);
if (error_code != MEDIA_VISION_ERROR_NONE)
    dlog_print(DLOG_ERROR, LOG_TAG, "error code = %d", error_code);

error_code = mv_destroy_engine_config(config);
if (error_code != MEDIA_VISION_ERROR_NONE)
    dlog_print(DLOG_ERROR, LOG_TAG, "error code = %d", error_code);

error_code = mv_roi_tracker_destroy(handle);
if (error_code != MEDIA_VISION_ERROR_NONE)
    dlog_print(DLOG_ERROR, LOG_TAG, "error code = %d", error_code);
  • Dependencies
    • Tizen 7.0 and Higher for Mobile
    • Tizen 7.0 and Higher for Wearable
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