treadscan 0.1.5

Tools for scanning tire tread(s).

treadscan

This package provides utilities for extracting tire tread (pattern) from images, or even from video of passing cars.

Three main classes are
Detector - picks out stopped cars from continoous footage (like at an intersection, under a traffic light).
Segmentor - finds ellipse defining car wheel in image (using image segmentation techniques).
Extractor - creates a tire model from the ellipse, then "unwraps" the tire tread (or rather part of the tire tread, as only about a quarter of the tread is visible).

Currently Segmentor works correctly only if the car has bright wheels (rims). But there is a way to also extract tire tread from images where this detection method fails, by manual input. In the extras folder, there is another module annotator.py containing the Annotator class and the script manual_annotation.py which uses it. The script manual_annotation.py takes an image as input, which it then allows the user to manually annotate.
The user places specific points over the image, which in turn creates the car wheel and tire model, from which the tire tread is then extracted as usual.

This GUI utilises the OpenCV window, using mouse position and keyboard input to place the points. So to place a point, user can hover over a location and press a specific key, or hold the key while dragging with the mouse.
The points which have to be placed manually are:

• T - top of car wheel (not the tire but the rim)
• B - bottom of car wheel
• R - right (or left) side

These 3 points form an ellipse, which defines the location of car wheel in image (red ellipse in the above image). Then the tire model is extrapolated from that, or can be further modified using the optional points:

• O - move outer tire ellipse (left yellow ellipse)
• S - tire sidewall height (height of yellow ellipses)
• W - tire width (move inner tire ellipse, right yellow ellipse)
• U - top of tread extraction (starting angle, top of green rectangle)
• I - bottom of tread extraction (ending angle, bottom of green rectangle)

Pressing SPACEBAR shows preview of extracted tread, BACKSPACE hides this preview. Pressing ENTER saves full size extracted tread as new image. Closing the window or pressing ESCAPE closes the window.

Additionally the treadscan_script.py in the extras folder can process footage (folder of images/video/stream) and extract the tread of each car from the footage. It has 3 modes: manual (user annotates each manually), semiauto (user annotates only those where Segmentor fails) and auto (images where Segmentor fails are discarded). Extracted treads are saved to a folder.