Common Types

Defines common types used by several components. More...

Data Structures
struct	VPIKeypoint
	Stores a keypoint coordinate. More...
struct	VPIHomographyTransform2D
	Stores a generic 2D homography transform. More...
struct	VPIBoundingBox
	Stores a generic 2D bounding box. More...

Macros
#define	VPI_TERMINATION_CRITERIA_ITERATIONS   (1u << 0)
	Defines the termination criteria macros. More...

Enumerations
enum	VPIInterpolationType
	Interpolation types supported by several algorithms. More...
enum	VPIBorderExtension
	Image border extension specify how pixel values outside of the image domain should be constructed. More...
enum	VPIOpticalFlowQuality
	Defines the quality of the optical flow algorithm. More...
enum	VPILockMode
	Defines the lock modes used by memory lock functions. More...
enum	VPIEventState
	Defines the states of the event. More...

Detailed Description

Defines common types used by several components.

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Data Structure Documentation

VPIKeypoint

struct VPIKeypoint

Stores a keypoint coordinate.

The coordinate is relative to the top-left corner of an image.

Definition at line 273 of file Types.h.

Collaboration diagram for VPIKeypoint:

Data Fields
float	x	Keypoint's x coordinate.
float	y	Keypoint's y coordinate.

VPIHomographyTransform2D

struct VPIHomographyTransform2D

Stores a generic 2D homography transform.

When only scale and translation transformation is needed, these parameters must be arranged in the matrix as follows:

\[ \begin{bmatrix} s_x & 0 & p_x \\ 0 & s_y & p_y \\ 0 & 0 & 1 \end{bmatrix} \]

Scaling \((s_x,s_y)\) is relative to the center of the patch, position \((p_x,p_y)\) is relative to the top-left of the image.

In the general case, given an homogeneous 2D point \(P(x,y,1)\) and the matrix \(M^{3x3}\), the Euclidean 2D point \(O(x,y)\) is defined as

\begin{align} T &= M \cdot P \\ O &= (T_x/T_z, T_y/T_z) \end{align}

Definition at line 303 of file Types.h.

Collaboration diagram for VPIHomographyTransform2D:

Data Fields
float	mat3[3][3]	3x3 homogeneous matrix that defines the homography.

VPIBoundingBox

struct VPIBoundingBox

Stores a generic 2D bounding box.

Although this structure can store a 2D bounding box transformed by any homography, most of the time it stores an axis-aligned bounding box. To retrieve it, do the following:

float x = xform.mat3[0][2];
float y = xform.mat3[1][2];
float w = width  * xform.mat3[0][0];
float h = height * xform.mat3[1][1];

Definition at line 323 of file Types.h.

Collaboration diagram for VPIBoundingBox:

Data Fields
float	height	Bounding box height.
float	width	Bounding box width.
VPIHomographyTransform2D	xform	Defines the bounding box top left corner and its homography.

Macro Definition Documentation

VPI_TERMINATION_CRITERIA_ITERATIONS

#define VPI_TERMINATION_CRITERIA_ITERATIONS   (1u << 0)

#include <vpi/Types.h>

Defines the termination criteria macros.

Termination based on maximum number of iterations.

Definition at line 404 of file Types.h.

Enumeration Type Documentation

VPIBorderExtension

enum VPIBorderExtension

#include <vpi/Types.h>

Image border extension specify how pixel values outside of the image domain should be constructed.

Enumerator
VPI_BORDER_ZERO	All pixels outside the image are considered to be zero.
VPI_BORDER_CLAMP	Border pixels are repeated indefinitely.
VPI_BORDER_REFLECT	edcba|abcde|edcba
VPI_BORDER_MIRROR	dedcb|abcde|dcbab

Definition at line 235 of file Types.h.

VPIEventState

enum VPIEventState

#include <vpi/Types.h>

Defines the states of the event.

Enumerator
VPI_EVENT_STATE_NOT_SIGNALED	Event is not signaled yet.
VPI_EVENT_STATE_SIGNALED	Event has been signaled.

Definition at line 461 of file Types.h.

VPIInterpolationType

enum VPIInterpolationType

#include <vpi/Interpolation.h>

Interpolation types supported by several algorithms.

Enumerator
VPI_INTERP_NEAREST	Nearest neighbor interpolation. \[ P(x,y) = \mathit{in}[\lfloor x+0.5 \rfloor, \lfloor y+0.5 \rfloor] \]
VPI_INTERP_LINEAR	Linear interpolation. Interpolation weights are defined as: \begin{align*} w_0(t)& \triangleq t-\lfloor t \rfloor \\ w_1(t)& \triangleq 1 - w_0(t) \\ \end{align*} Bilinear-interpolated value is given by the formula below: \[ P(x,y) = \sum_{p=0}^1 \sum_{q=0}^1 \mathit{in}[\lfloor x \rfloor+p, \lfloor y \rfloor+q]w_p(x)w_q(y) \]
VPI_INTERP_CATMULL_ROM	Catmull-Rom cubic interpolation. Catmull-Rom interpolation weights with \(A=-0.5\) are defined as follows: \begin{eqnarray*} w_0(t) &\triangleq& A(t+1)^3 &-& 5A(t+1)^2 &+& 8A(t+1) &-& 4A \\ w_1(t) &\triangleq& (A+2)t^3 &-& (A+3)t^2 &\nonumber& &+& 1 \\ w_2(t) &\triangleq& (A+2)(1-t)^3 &-& (A+3)(1-t)^2 &\nonumber& &+& 1 \\ w_3(t) &\triangleq& \rlap{1 - w_0(t) - w_1(t) - w_2(t) } \end{eqnarray*} Bicubic-interpolated value is given by the formula below: \[ P(x,y) = \sum_{p=-1}^2 \sum_{q=-1}^2 \mathit{in}[\lfloor x \rfloor+p, \lfloor y \rfloor+q]w_p(x)w_q(y) \]

Definition at line 69 of file Interpolation.h.

VPILockMode

enum VPILockMode

#include <vpi/Types.h>

Defines the lock modes used by memory lock functions.

Enumerator
VPI_LOCK_READ	Lock memory only for reading. Writing to the memory when locking for reading leads to undefined behavior.
VPI_LOCK_WRITE	Lock memory only for writing. Reading to the memory when locking for reading leads to undefined behavior. It is expected that the whole memory is written to. If there are regions not written, it might not be updated correctly during unlock. In this case, it's better to use VPI_LOCK_READ_WRITE. It might be slightly efficient to lock only for writing, specially when performing non-shared memory mapping.
VPI_LOCK_READ_WRITE	Lock memory for reading and writing.

Definition at line 379 of file Types.h.

VPIOpticalFlowQuality

enum VPIOpticalFlowQuality

#include <vpi/Types.h>

Defines the quality of the optical flow algorithm.

Enumerator
VPI_OPTICAL_FLOW_QUALITY_LOW	Fast but low quality optical flow implementation.
VPI_OPTICAL_FLOW_QUALITY_MEDIUM	Speed and quality in between of VPI_OPTICAL_FLOW_QUALITY_LOW and VPI_OPTICAL_FLOW_QUALITY_HIGH.
VPI_OPTICAL_FLOW_QUALITY_HIGH	Slow but high quality optical flow implementation.

Definition at line 363 of file Types.h.