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https://github.com/oleander/ransac-and-hough-transform-java
Java implementation of the Hough transform and RANSAC algorithm
https://github.com/oleander/ransac-and-hough-transform-java
Last synced: about 2 months ago
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Java implementation of the Hough transform and RANSAC algorithm
- Host: GitHub
- URL: https://github.com/oleander/ransac-and-hough-transform-java
- Owner: oleander
- Created: 2013-01-10T14:41:55.000Z (about 12 years ago)
- Default Branch: master
- Last Pushed: 2013-01-25T23:15:10.000Z (almost 12 years ago)
- Last Synced: 2023-04-10T09:39:52.014Z (almost 2 years ago)
- Language: JavaScript
- Size: 566 KB
- Stars: 6
- Watchers: 1
- Forks: 5
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# RANSAC and Hough Transform
Java implementation of the Hough transform and RANSAC algorithm
## RANSAC
- The constructor reads the data points from a text file into a list
- showCanvas calls execute
- for (maxIter iterations)
- The execute method chooses 3 points from the data list at random. Their indices are stored in the concensusSet.
- A circle that passes through all 3 points is chosen as the current circle model
for (all points in the data set)
- getoffset is responsible for calculating the difference between the points and the circumference of the circle
- Points that are within *threshold* distance are added to the consenus set
- The best model so far (as determined by the highest number of points in the consenus set) is kept track on during the iteration
- The best model is returned
- showCanvas draws the data points, the best circle and the smallest width annulus on a canvas and displays the result to the user
### Methods
- (+) showCanvas() *Displays the data points and the calculated circles on a canvas.*
- (+) execute() *Runs the RANSAC algorithm.*
- (-) getOffset() *Calculate the distance between a point and the center of a circle*
- (-) getCircle() *Find the circle that passes through the three given points*
- (-) getNPoints() *Choose n data points at random*
### Illustrations
Points from *points.r.data* are being used.
- Cirlces (x, y, r, number of points)
- 20, 100, 100, 100
- Noise: 900 points randomly selected between -200 and 200
- smallestRadius=92.17273473900397
- highestRadius=111.01668853035679
- 18.843953791352817
## Hough Transform
- The constructor reads the data points from a text file into a list
- A wrapped 3D array - the accumulator - is used to store information about potential circles. A circle is identified by pixel ranges for x, y and radius
- execute()
- for (all points)
- all circles that could have *point* on its circumference are calculated
- for (all circles)
- the cell in the accumulator is incremented for the given circle
- filterNeighbours removes circles that lie too close to each other. Circles with a high count are preferred.
- showCanvas draws the points and the identified circles
The smallest width annuli for the Hough circle suffers from some offset problems, possibly caused by rounding errors.
### Methods
- (+) execute() *Executes the Hough Transform algorithm.*
- (+) showCanvas() *Render view based on this.pixels.*
- (-) getCircles() *Finds every other circle that has @point.getY() and @point.getX() as its center*
### Illustrations
Points from *points.ht.data* are being used.
- Circles (x, y, r, number of points)
- 0, 0, 50, 50
- 100, 140, 110, 50
- 0, 50, 50, 50
- 20, 100, 100, 100
- Noise: 120 points randomly selected between -200 and 200
