The `cv2.circle()` method in OpenCV constructs a circle on an image at a specified center coordinate with a given radius. This method requires an image object, center coordinates, radius, color, and line thickness.

```python
img = cv2.circle(frame, (100, 100), 60, (0, 0, 255), -1)
```

In this example, the thickness is specified as `-1`, which fills the circle in completely instead of just drawing the outline.

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OpenCV provides built-in methods to draw geometric shapes, such as lines, rectangles, and circles, directly onto images. These drawing operations are frequently used in computer vision tasks to annotate frames, highlight specific regions of interest, and add graphical overlays.

Shape Creation in OpenCV

Remember that the pixel information is stored inside of an array. Therefore, there is a similar coordinate system that maps the screen or an image. The top left will be ```(0,0)```. 
The cv2.line() method requires the image object, two coordinate values, color and pixel thickness. 
```python
img = cv2.line(frame, (0,0), (width, height), (255, 0,0), 10)
cv2.imshow('frame', img)
```

To draw multiple lines, we need to draw the new line on the modified img object. 
```python
img = cv2.line(frame, (0,0), (width, height), (255, 0,0), 10)
img = cv2.line(img, (0,height), (width, 0), (0, 255,0), 5)
cv2.imshow('frame', img)
```



Line Method

This method requires an img object, top left and bottom right coordinate, color and line thickness. 
```python
img = cv2.rectangle(frame, (100,100), (200,200), (128, 128, 128), 5)
```
If the thickness is set to be -1 instead of a positive integer, then it would fill the rectangle in completely instead of just having an outline. 

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