flowvid 0.2.1

Optical Flow video tools

Toolkit to generate customized visualizations related to optical flow (beta 0.2.1)
PyPI page · Installation · Examples · Presets

Table of contents

• Installation
• Quick start
  • Python library
• Acknowledgements

Installation

flowvid is available as a PyPI package:

pip3 install flowvid

Or you can install it directly from Github:

pip3 install git+https://github.com/diegoroyo/flowvid/

or you can clone the repo:

git clone https://github.com/diegoroyo/flowvid.git
cd flowvid
scripts/local_install.sh

Quick start

Flowvid is a python library for video generation, but it also contains several video presets with an user-friendly assistant:

• Presets can be listed using python3 -m flowvid -h

$ python3 -m flowvid -h

usage: flowvid [-h] preset

Generate an optical flow visualization using the available presets.

Preset can be one of:
  color_flow: Convert flow data to RGB using the Middlebury representation
  color_epe: Calculate endpoint error and generate a video representation
  plot_epe: Generate a pyplot plot with the EPE distribution in all frames
  track_points: Place points in a image and see how flow moves them
  track_side_by_side: Place points in a image and see how flow can track them

positional arguments:
  preset      Video preset, see above.

optional arguments:
  -h, --help  show this help message and exit

• Example: converting flow files to rgb and saving into a video

$ python3 -m flowvid color_flow

Flow files directory (default: flo): path/to/flo/dir 
Vector normalize type (video, [frame], none): video
Normalization clamp percentage (default: 1.0): 0.8
Normalization gamma curve exponent (default: 1.0): 1.5
Video framerate (default: 24): 12
Output video name (default: output_color_flow.mp4): flowcolors.mp4 

Here are some examples illustrating the other presets' results:

color_epe	plot_epe

track_points	track_side_by_side

Python library

If you want to generate more complex or customized videos, you can easily use flowvid's tools:

• You can check the documentation and example usages here.
• You can check the source code for the given presets here.

import flowvid as fv

# Read flow files data
flo_data = fv.input.flo('path/to/flo/dir')

# Normalize each file (so max flow's module is 1),
# necessary to convert to RGB
flo_data = fv.normalize_frame(flo_data)
rgb_data = fv.flow_to_rgb(flo_data)

# Output as video
out = fv.output.video(filename='output.mp4', framerate=24)
out.add_all(rgb_data)

Acknowledgements

• Logo made by Github user Aeri (see profile).

• Flow to RGB conversion is based on C. Liu's work.

C. Liu. Beyond Pixels: Exploring New Representations and Applications for Motion Analysis. Doctoral Thesis. Massachusetts Institute of Technology. May 2009.