Class CameraCoveredDetector

Namespace

VisioForge.Core.CV

Assembly

VisioForge.Core.CV.dll

Detects when a camera lens is covered or obscured using edge detection algorithms.

public class CameraCoveredDetector : IDisposable, IVideoProcessor

Inheritance

object

CameraCoveredDetector

Implements

IDisposable

IVideoProcessor

Inherited Members

object.Equals(object?)

object.Equals(object?, object?)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object?, object?)

object.ToString()

Remarks

The VisioForge.Core.CV.CameraCoveredDetector class analyzes video frames to determine if the camera view is blocked by an object or covering. It uses Canny edge detection to count the number of edges in each frame; when the edge count falls below a threshold, it indicates the camera is likely covered. This is useful for surveillance systems, security applications, and monitoring whether a camera has been tampered with or blocked.

Constructors

CameraCoveredDetector()

Initializes a new instance of the VisioForge.Core.CV.CameraCoveredDetector class.

public CameraCoveredDetector()

Properties

FramesToSkip

Gets or sets the number of frames to skip between detections.

public int FramesToSkip { get; set; }

Property Value

int

Remarks

Increasing this value improves performance by analyzing fewer frames but may delay detection of camera coverage. For real-time applications processing 30fps video, a skip value of 5-10 still provides timely notifications while reducing CPU usage.

Threshold

Gets or sets the threshold level for determining if the camera is covered.

public int Threshold { get; set; }

Property Value

int

Remarks

This threshold must be tuned based on your specific camera and scene:

• Higher quality cameras with more detail require higher thresholds
• Complex scenes (many objects/textures) have higher normal edge counts
• Simple scenes (blank walls, sky) have lower normal edge counts

Test by monitoring edge counts in normal operation to find an appropriate threshold.

VideoScale

Gets or sets the scale factor for video processing to improve performance.

public double VideoScale { get; set; }

Property Value

double

Remarks

Reducing the scale improves performance significantly while maintaining accuracy for coverage detection. A typical value is 0.25-0.5 for HD video sources.

Methods

Dispose(bool)

Releases unmanaged and - optionally - managed resources.

protected virtual void Dispose(bool disposing)

Parameters

disposing bool

true to release both managed and unmanaged resources; false to release only unmanaged resources.

Dispose()

Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

public void Dispose()

~CameraCoveredDetector()

Finalizes an instance of the VisioForge.Core.CV.CameraCoveredDetector class.

protected ~CameraCoveredDetector()

GetSupportedFrameFormats()

Gets the video frame formats supported by this processor.

public VideoFormatX[] GetSupportedFrameFormats()

Returns

VideoFormatX[]

An array containing VisioForge.Core.Types.X.VideoFormatX.RGB, which is the required format for processing.

ProcessFrame(VideoFrame)

Processes the frame. Frame may be skipped according to the settings.

public void ProcessFrame(VideoFrame frame)

Parameters

frame VideoFrame

The frame.

ProcessFrame(VideoFrameX)

Processes a video frame to detect if the camera is covered.

public void ProcessFrame(VideoFrameX frame)

Parameters

frame VideoFrameX

The video frame to analyze. Must be in RGB or BGR format.

Remarks

This method converts the frame to grayscale, applies Canny edge detection, and counts the number of edge pixels. If the count is below the threshold and enough frames have been processed (based on VisioForge.Core.CV.CameraCoveredDetector.FramesToSkip), the VisioForge.Core.CV.CameraCoveredDetector.OnCameraCovered
event is raised. Frames are skipped according to the FramesToSkip setting to improve performance.

Exceptions

Exception

Thrown when the frame format is not RGB or BGR.

SetContext(BaseContext)

Sets the context.

public void SetContext(BaseContext context)

Parameters

context BaseContext

The context.

OnCameraCovered

Occurs when the camera is detected as being covered or obscured.

public event EventHandler<CameraCoveredDetectorEventArgs> OnCameraCovered

Event Type

EventHandler<CameraCoveredDetectorEventArgs>

Remarks

This event is raised when the edge count falls below the VisioForge.Core.CV.CameraCoveredDetector.Threshold value, indicating the camera view is likely blocked. The event args contain the actual edge count which can be logged for threshold tuning purposes.