Harris Corners

Detect Harris keypoints in an image, usually used in keypoint tracking. More...

Data Structures
struct	VPIHarrisCornerDetectorParams
	Structure that defines the parameters for vpiSubmitHarrisCornerDetector. More...

Functions
VPIStatus	vpiInitHarrisCornerDetectorParams (VPIHarrisCornerDetectorParams *params)
	Initializes VPIHarrisCornerDetectorParams with default values. More...
VPIStatus	vpiCreateHarrisCornerDetector (uint64_t backends, int32_t inputWidth, int32_t inputHeight, VPIPayload *payload)
	Creates a Harris Corner Detector payload. More...
VPIStatus	vpiSubmitHarrisCornerDetector (VPIStream stream, uint64_t backend, VPIPayload payload, VPIImage input, VPIArray outFeatures, VPIArray outScores, const VPIHarrisCornerDetectorParams *params)
	Submits a Harris Corner Detector operation to the stream. More...

Detailed Description

Detect Harris keypoints in an image, usually used in keypoint tracking.

Refer to Harris Corner Detector for more details and usage examples.

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Data Structure Documentation

VPIHarrisCornerDetectorParams

struct VPIHarrisCornerDetectorParams

Structure that defines the parameters for vpiSubmitHarrisCornerDetector.

Definition at line 81 of file HarrisCorners.h.

Collaboration diagram for VPIHarrisCornerDetectorParams:

Data Fields
int32_t	gradientSize	Gradient window size. Must be 3, 5 or 7.
int32_t	blockSize	Block window size used to compute the Harris Corner score. Must be 3, 5 or 7.
float	strengthThresh	Specifies the minimum threshold with which to eliminate Harris Corner scores. Threshold is dependent on input image range. For image format U8 and S8 it is in the range of [0-20]. Can be larger for U16 and S16. Must be >= 0.
float	sensitivity	Specifies sensitivity threshold from the Harris-Stephens equation.
float	minNMSDistance	Non-maximum suppression radius, set to 0 to disable it. On PVA backend, this must be set to 8.

Function Documentation

vpiInitHarrisCornerDetectorParams()

VPIStatus vpiInitHarrisCornerDetectorParams

(

VPIHarrisCornerDetectorParams *

params

)

#include <vpi/algo/HarrisCorners.h>

Initializes VPIHarrisCornerDetectorParams with default values.

Default values are:

• gradientSize: 3
• blockSize: 3
• strengthThresh: 20
• sensitivity: 0.0625
• minNMSDistance: 8

Return values

VPI_ERROR_INVALID_ARGUMENT	params is NULL.
VPI_SUCCESS	Operation executed successfully.

vpiCreateHarrisCornerDetector()

VPIStatus vpiCreateHarrisCornerDetector	(	uint64_t	backends,
		int32_t	inputWidth,
		int32_t	inputHeight,
		VPIPayload *	payload
	)

#include <vpi/algo/HarrisCorners.h>

Creates a Harris Corner Detector payload.

This function allocates all temporary memory needed by the algorithm.

Parameters

[in]	backends	VPI backends that are eligible to execute the algorithm. Valid values: VPI_BACKEND_CPU VPI_BACKEND_CUDA VPI_BACKEND_PVA Backend must be enabled in current context.
[in]	inputWidth,inputHeight	Dimensions of the input image that will be used with this payload. On PVA dimensions limited to minimum of 160x120, maximum of 3264x2448. Must be >= 0 (other backends).
[out]	payload	Pointer to the payload variable that receives the created handle.

Return values

VPI_ERROR_INVALID_ARGUMENT	payload is NULL.
VPI_ERROR_INVALID_ARGUMENT	inputWidth or inputHeight outside valid range.
VPI_ERROR_INVALID_ARGUMENT	backends refers to an invalid backend.
VPI_ERROR_INVALID_OPERATION	Backend hardware not available.
VPI_ERROR_NOT_IMPLEMENTED	Harris Corner Detector algorithm is not supported by given backend.
VPI_ERROR_INVALID_CONTEXT	Current context is destroyed.
VPI_ERROR_OUT_OF_MEMORY	Cannot allocate required resources.
VPI_ERROR_INVALID_OPERATION	Backend isn't enabled in current context.
VPI_SUCCESS	Operation executed successfully.

vpiSubmitHarrisCornerDetector()

VPIStatus vpiSubmitHarrisCornerDetector	(	VPIStream	stream,
		uint64_t	backend,
		VPIPayload	payload,
		VPIImage	input,
		VPIArray	outFeatures,
		VPIArray	outScores,
		const VPIHarrisCornerDetectorParams *	params
	)

#include <vpi/algo/HarrisCorners.h>

Submits a Harris Corner Detector operation to the stream.

Parameters

[in]	stream	The stream where the operation will be queued in. Must not be NULL. Stream must have enabled the backends that will execute the algorithm.
[in]	backend	Backend that will execute the algorithm. Must be the backend specified during payload creation or 0 as a shorthand to use this backend.
[in]	payload	Payload to be submitted along the other parameters.
[in]	input	Input image from where the Harris corners will be extracted. Must not be NULL. Image must have enabled the backends that will execute the algorithm. The accepted image formats are: VPI_IMAGE_FORMAT_U8 VPI_IMAGE_FORMAT_S8 VPI_IMAGE_FORMAT_U16 VPI_IMAGE_FORMAT_S16 (PVA backend only supports this format)
[out]	outFeatures	Array that will receive the detected corners. Array size is updated with the number of corners found. Must not be NULL. It must have type VPI_ARRAY_TYPE_KEYPOINT_F32. Array must have enabled the backends that will execute the algorithm.
[out]	outScores	Array that will receive the corners' scores. Array size matches outFeatures array' size. Must not be NULL. It must have type VPI_ARRAY_TYPE_U32. Array must have enabled the backends that will execute the algorithm. Must have same capacity as outFeatures.
[in]	params	Pointer to a VPIHarrisCornerDetectorParams with parameters for this algorithm invocation. These parameters can vary in every call and will be copied internally, no need to keep the object around.

Return values

VPI_ERROR_INVALID_ARGUMENT	stream is NULL.
VPI_ERROR_INVALID_ARGUMENT	input, outFeatures or outScores are NULL.
VPI_ERROR_INVALID_ARGUMENT	payload is not created by vpiCreateHarrisCornerDetector.
VPI_ERROR_INVALID_ARGUMENT	Strength threshold in params outside valid range.
VPI_ERROR_INVALID_ARGUMENT	Output arrays must have same capacity.
VPI_ERROR_INVALID_ARGUMENT	Unsupported outFeatures or outScores type.
VPI_ERROR_INVALID_ARGUMENT	Invalid input dimensions.
VPI_ERROR_INVALID_PAYLOAD_TYPE	payload is invalid.
VPI_ERROR_INVALID_IMAGE_FORMAT	Unsupported input format.
VPI_ERROR_INVALID_OPERATION	The needed backends aren't enabled in stream, outFeatures or outScores.
VPI_SUCCESS	Operation executed successfully.