NVIDIA VPI GStreamer Plug-in - Examples - Perspective Warp

GstVPI
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Evaluating GstVPI Getting the Code Building the Plugin
Examples
Gaussian Filter Undistort Harris Keypoints Detector KLT Tracker Perspective Warp Overlay Videoconvert Videoscale Convolution Separable Convolution
Performance
Nano TX1 TX2 Xavier
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Introduction

The vpiwarp element applies the Perspective Warp algorithm from the NVIDIA VPI library to a video stream.

Element properties

• backend
  

Backend to use to execute VPI algorithms. Available options:

cpu: CPU backend

cuda: CUDA backend

pva: PVA backend (Xavier only)

vic: VIC backend

Flags: readable, writable
Default: "cuda"

• interpolator
  

Interpolation method to be used. Available options:

nearest: Nearest neighbor interpolation

linear: Fast linear interpolation

catmull: Fast Catmull-Ron cubic interpolation

Flags: readable, writable
Default: linear

• behavior
  

Flag to modify algorithm behavior. Available options:

direct: The provided transformation matrix is direct, so the algorithm will invert it internally

inverted: The provided transformation matrix is already inverted, so the algorithm will not invert it

Flags: readable, writable
Default: direct

• transformation
  

3x3 transformation matrix. If not provided, no transformation will be performed.
Usage example: <<1.0,0.0,0.0>,<0.0,1.0,0.0>,<0.0,0.0,1.0>>
Type: GstValueArray of GValues of type GstValueArray
Flags: readable, writable
Default: <<1.0,0.0,0.0>,<0.0,1.0,0.0>,<0.0,0.0,1.0>>

• demo
  

Put the element in demo mode to showcase its capabilities. In this mode, the incoming image will be rotated in the 3D space and projected back to the image plane. Will override the transformation matrix.
Type: Boolean
Flags: readable, writable
Default: false

Perspective Warp Example

The following example pipe will help you apply perspective warp to the input video stream from your camera. You may modify the properties values according to the information above.

• Unified memory

gst-launch-1.0 nvarguscamerasrc ! nvvidconv ! 'video/x-raw' ! vpiupload ! vpiwarp transformation="<<0.5386, 0.1419, -74.0>, <-0.4399, 0.8662, 291.5>, <-0.0005, 0.0003, 1.0>>" ! vpidownload ! nvvidconv ! 'video/x-raw(memory:NVMM),format=I420' ! nvoverlaysink

• NVMM memory

gst-launch-1.0 nvarguscamerasrc ! nvvidconv bl-output=false ! 'video/x-raw(memory:NVMM)' ! vpiupload ! vpiwarp transformation="<<0.5386, 0.1419, -74.0>, <-0.4399, 0.8662, 291.5>, <-0.0005, 0.0003, 1.0>>" ! vpidownload ! nvvidconv ! 'video/x-raw(memory:NVMM),format=I420' ! nvoverlaysink