NVIDIA VPI GStreamer Plug-in - Examples - Perspective Warp
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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
Alternative display pipeline.
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' ! nvvidconv ! autovideosink