<p>You can use a shear, or equivalently a rotation by 45, scale along one of the axes, rotate back (which is equivalent to the shear which you are looking for).</p>

<p>EDIT: On second thought, you don't need to even rotate back unless your circle is marked, since a circle is rotation invariant (if the rotation is around its center).</p>

CC BY-SA 4.0
2019-04-16T10:46:31.853Z
2019-04-20T21:42:43.427Z
2019-04-20T21:42:43.427Z
lightxbulb
<p>I have an ellipse which has -45 degree axis.</p>

<p>How can I transform the ellipse into a circle? Can I use shear transformation along the x/y axis?</p>

<p><a href="https://i.sstatic.net/aMJhX.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/aMJhX.jpg" alt="enter image description here"></a></p>

CC BY-SA 4.0
2019-04-18T20:40:57.170Z
Do you just require the outcome to be a circle (any size circle), or does the diagram indicate that you require specifically that size circle from that size ellipse?
trichoplax is on Codidact now
CC BY-SA 4.0
2019-04-19T01:33:59.533Z
The circle size can be arbitrary size. I just want the transformed into complete circle.
thank you very much.
Ick-Sung Choi
<2d-graphics>
How can I transform an ellipse into a circle?
Ick-Sung Choi
# How can I transform an ellipse into a circle?

(Asked by: username_0 on 2019-04-15)

I have an ellipse which has -45 degree axis.

How can I transform the ellipse into a circle? Can I use shear transformation along the x/y axis?

[![enter image description here](https://i.sstatic.net/aMJhX.jpg)](https://i.sstatic.net/aMJhX.jpg)

**Tags:** 2d-graphics

> **Comments:**
> **username_1**: Do you just require the outcome to be a circle (any size circle), or does the diagram indicate that you require specifically that size circle from that size ellipse?  
> **username_0**: The circle size can be arbitrary size. I just want the transformed into complete circle. thank you very much.  

---

## 1 answers

### Answer by username_2 on 2019-04-16. Score: 4

You can use a shear, or equivalently a rotation by 45, scale along one of the axes, rotate back (which is equivalent to the shear which you are looking for).

EDIT: On second thought, you don't need to even rotate back unless your circle is marked, since a circle is rotation invariant (if the rotation is around its center).


---

