# Hough Transform 2D Circles Image Filter GetCircles patch.

**URL:** https://discourse.itk.org/t/hough-transform-2d-circles-image-filter-getcircles-patch/350
**Category:** Algorithms
**Created:** [October 24, 2017, 5:26pm UTC](https://discourse.itk.org/t/hough-transform-2d-circles-image-filter-getcircles-patch/350 "2017-10-24T17:26:37Z")
**Posts on this page:** 1
**Showing post:** 53

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### Author: ![tim-evain](https://discourse.itk.org/user_avatar/discourse.itk.org/tim-evain/32/220_2.png) [@tim-evain](https://discourse.itk.org/u/tim-evain)
#### Post date: [February 2, 2018, 3:20pm UTC](https://discourse.itk.org/t/hough-transform-2d-circles-image-filter-getcircles-patch/350/53 "2018-02-02T15:20:21Z")

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Hi Niels!

I think this is a great improvement over the previous system 🙂.  
Some thoughts:

- On “ToDo 3” : maybe start with the definition of Circle into the Hough file, and see afterward if there is really a need for other filters to use it ?

- Circles are found by an index center, but defined as a point afterward, leading to a confusing representation. An user that doesn’t check the code will think that the circle is defined in world coordinates, but the radius and center are in fact in continuous indexes. I think it should be harmonized, either by making the center an index, or putting all values in world coordinates (I think the latter is preferable).

- On “ToDo 2” : it depends on the previous choice. If the circle is in index system, there is no need for template.

- Since the return type of GetCircles() will change, I wonder if a vector is not preferable over a list. The syntax to access circles with lists is heavier in my opinion.

Anyway thanks for the time you put into making this!

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