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C Sample Point Cloud

Function description: Connect the device to open the stream, generate a depth point cloud or RGBD point cloud and save it as a ply format file, and exit the program through the ESC_KEY key

This example is based on the C++High Level API for demonstration

1. Create a point cloud and save it as a ply file function. The detailed description of the ply file format can be viewed on the network

    //Save point cloud data to ply
    void save_points_to_ply( ob_frame* frame, const char* fileName ) {
        int pointsSize = ob_frame_data_size( frame, &error ) / sizeof( ob_point );
        check_error( error );
    
        FILE* fp = fopen( fileName, "wb+" );
        fprintf( fp, "ply\n" );
        fprintf( fp, "format ascii 1.0\n" );
        fprintf( fp, "element vertex %d\n", pointsSize );
        fprintf( fp, "property float x\n" );
        fprintf( fp, "property float y\n" );
        fprintf( fp, "property float z\n" );
        fprintf( fp, "end_header\n" );
    
        ob_point* point = ( ob_point* )ob_frame_data( frame, &error );
        check_error( error );
        for ( int i = 0; i < pointsSize; i++ ) {
            fprintf( fp, "%.3f %.3f %.3f\n", point->x, point->y, point->z );
            point++;
        }
    
        fflush( fp );
        fclose( fp );
    }
    
    // Save color point cloud data to ply
    void save_rgb_points_to_ply( ob_frame* frame, const char* fileName ) {
        int pointsSize = ob_frame_data_size( frame, &error ) / sizeof( ob_color_point );
        check_error( error );
    
        FILE* fp = fopen( fileName, "wb+" );
        fprintf( fp, "ply\n" );
        fprintf( fp, "format ascii 1.0\n" );
        fprintf( fp, "element vertex %d\n", pointsSize );
        fprintf( fp, "property float x\n" );
        fprintf( fp, "property float y\n" );
        fprintf( fp, "property float z\n" );
        fprintf( fp, "property uchar red\n" );
        fprintf( fp, "property uchar green\n" );
        fprintf( fp, "property uchar blue\n" );
        fprintf( fp, "end_header\n" );
    
        ob_color_point* point = ( ob_color_point* )ob_frame_data( frame, &error );
        check_error( error );
    
        for ( int i = 0; i < pointsSize; i++ ) {
            fprintf( fp, "%.3f %.3f %.3f %d %d %d\n", point->x, point->y, point->z, ( int )point->r, ( int )point->g, ( int )point->b );
            point++;
        }
    
        fflush( fp );
        fclose( fp );
    }

2. Create Pipeline and stream Configuration

    //Create a pipeline to open the Color and Depth streams after connecting devices
    pipeline = ob_create_pipeline( &error );
    //Create a config to configure the resolution, frame rate, and format of the Color and Depth streams
    ob_config* config = ob_create_config( &error );
    
    
    //Configure Color Stream
    ob_stream_profile_list *colorProfiles = ob_pipeline_get_stream_profile_list(pipeline, OB_SENSOR_COLOR, &error);
    if(error) {
        printf("Current device is not support color sensor!\n");
        ob_delete_error(error);
        error = NULL;
        // Turn on D2C alignment, which needs to be turned on when generating RGBD point clouds
        ob_config_set_align_mode(config, ALIGN_DISABLE, &error);
        check_error(error);
    }
    // Open the default profile of Color Sensor, which can be configured through the configuration file
    if(colorProfiles) {
        color_profile = ob_stream_profile_list_get_profile(colorProfiles, OB_PROFILE_DEFAULT, &error);
    }
    
        //Configure Depth Stream
    if(color_profile) {
        // Try find supported depth to color align hardware mode profile
        depthProfiles = ob_get_d2c_depth_profile_list(pipeline, color_profile, ALIGN_D2C_HW_MODE, &error);
        check_error(error);
        int d2cCount = ob_stream_profile_list_count(depthProfiles, &error);
        check_error(error);
        if(d2cCount > 0) {
            align_mode = ALIGN_D2C_HW_MODE;
        }
        else {
            // Try find supported depth to color align software mode profile
            depthProfiles = ob_get_d2c_depth_profile_list(pipeline, color_profile, ALIGN_D2C_SW_MODE, &error);
            check_error(error);
            d2cCount = ob_stream_profile_list_count(depthProfiles, &error);
            check_error(error);
            if(d2cCount > 0) {
                align_mode = ALIGN_D2C_SW_MODE;
            }
        }
    }
    else {
        depthProfiles = ob_pipeline_get_stream_profile_list(pipeline, OB_SENSOR_DEPTH, &error);
        check_error(error);
    }

3. Turn on device D2C function

    // Turn on D2C alignment, which needs to be turned on when generating RGBD point clouds
    ob_config_set_align_mode(config, align_mode, &error);

4. Start pipeline

    ob_pipeline_start_with_config(pipeline, config, &error);

5. Create a point cloud filter after opening the stream

 Point cloud filters are used to convert depth and color frame data into point cloud data. The purpose of creating a point cloud filter after streaming is to enable the SDK to automatically set camera parameters based on the current streaming configuration. Of course, you can also set it up yourself.

    // Create a point cloud Filter object (device parameters will be obtained inside the Pipeline when the point cloud filter is created, so try to configure
    // the device before creating the filter)
    ob_filter *point_cloud = ob_create_pointcloud_filter(&error);
    check_error(error);
    
    // Get the current open-stream camera parameters from the pipeline and pass them to the point cloud filter
    ob_camera_param camera_param = ob_pipeline_get_camera_param(pipeline, &error);
    check_error(error);
    ob_pointcloud_filter_set_camera_param(point_cloud, camera_param, &error);
    check_error(error);

6. Start the main loop which calls the point cloud filter based on user keys to generate depth point cloud or RGBD point cloud data, and save it as a ply file.

    // Waiting for one frame of data with a timeout of 100ms
    ob_frame *frameset = ob_pipeline_wait_for_frameset(pipeline, 100, &error);
    check_error(error);
    if(frameset != NULL) {
        // get depth value scale
        ob_frame *depth_frame = ob_frameset_depth_frame(frameset, &error);
        check_error(error);
        if(depth_frame == NULL) {
            continue;
        }
    
        // get depth value scale
        float depth_value_scale = ob_depth_frame_get_value_scale(depth_frame, &error);
        check_error(error);
    
        // delete depth frame
        ob_delete_frame(depth_frame, &error);
        check_error(error);
    
        // point position value multiply depth value scale to convert uint to millimeter (for some devices, the default depth value uint is not
        // millimeter)
        ob_pointcloud_filter_set_position_data_scale(point_cloud, depth_value_scale, &error);
        check_error(error);
    
        ob_pointcloud_filter_set_point_format(point_cloud, OB_FORMAT_RGB_POINT, &error);
        check_error(error);
        ob_frame *pointsFrame = ob_filter_process(point_cloud, frameset, &error);
        check_error(error);
        if(pointsFrame != NULL) {
            save_rgb_points_to_ply(pointsFrame, "rgb_points.ply");
            printf("rgb_points.ply Saved\n");
            ob_delete_frame(pointsFrame, &error);
            check_error(error);
            points_created = true;
        }
        ob_delete_frame(frameset, &error);  // Destroy frameSet to reclaim memory
        check_error(error);
        if(points_created) {
            break;
        }
    }

7.After the main loop exits, stop the stream and destroy the recycled resources

    // stop pipeline
    ob_pipeline_stop(pipeline, &error);
    check_error(error);
    
    // destroy pipeline
    ob_delete_pipeline(pipeline, &error);
    check_error(error);
    
    // destroy config
    ob_delete_config(config, &error);
    check_error(error);
    
    // destroy profile
    ob_delete_stream_profile(depth_profile, &error);
    check_error(error);
    
    // destroy profile
    ob_delete_stream_profile(color_profile, &error);
    check_error(error);
    
    // destroy profile list
    ob_delete_stream_profile_list(colorProfiles, &error);
    check_error(error);
    
    ob_delete_stream_profile_list(depthProfiles, &error);
    check_error(error);

8. Expected Output

image