I need the approximate radii of the following ellipse.
The bottom/top and left/right radii should be the same nevertheless need to be checked. Which means 4 radii should be the result of my code. I did the following in paint, the green circle should give me the top radius and red the left (the right and bottom one aren't drawn here).
The idea I'm working on is to crop the image (left/right/top/bottom side) and approximate circles to the cropped images. With the cv2.findContours-feature some white pixels get recognized as highlighted here.
Is there a way to approximate my drawn red circle from above with these given coordinates? The problems I've seen on the internet are all with a given center point or angle which I don't have. Is there a cv2 function that draws circles with only some given coordinates or something similar?
Use this function : cv2.fitEllipse(points) and pass contour points -Ziri
Yes this did the trick. I got the radii after your function with:
(x, y), radius = cv2.minEnclosingCircle(i)
Related
My project is about image detection. I am using 1 camera and have 2 shapes (rectangle and triangle) placed on a flat surface. I have successfully been able to:
Detect the contours
Detect the area of the contours
Make a relation between both areas and the distances, to be able to calculate both distances from the camera
Calculate the lengths, corner coordinates and the angle of each corner in both shapes
Now I need to calculate the angle of rotation of the whole surface when rotated around the x-axis (up & down), y-axis (left & right) and both axes (oblique). This can be seen in the gif I provided. The default angle (0 degrees) is when the surface is parallel to the camera, and any rotation would mean that an angle around 1 or both axes is present.
P.S When the surface is rotating around both axes (oblique), both angles have to be detected separately. For example, I would get 14° x-axis & 27° y-axis.
Any help would be appreciated.
I want to visualize results of keypoint tracking algorithm in python. I have a sequence of (Image, Keypoint) pairs (video basically). Tracking algorithm is strong enough to give me subpixel accuracy. But i have no idea, how to visualize it properly.
I tried to round my coordinates and draw a circle by cv2.circle(image, (int(round(x)), int(round(y)))), but it leads to visual jittering of my keypoints due to small image resolution.
I checked OpenCV, Pillow, skimage, Pygame (pygame.draw.circle). All of them cannot properly draw circle with float coordinates.
DIPlib has the function DrawBandlimitedBall(), which draws a disk or a circle with smooth transitions and with floating-point origin coordinates (disclosure: I'm one of the authors). You might need to draw the circle in an empty image, then blend it in to get the effect you are looking for. Code would look something like this:
import diplib as dip
img = dip.ImageRead('/Users/cris/dip/images/flamingo.tif')
p = [366.4, 219.1]
# Create an empty image and draw a circle in it
circle = dip.Image(img.Sizes(), 1, 'SFLOAT')
circle.Fill(0)
dip.DrawBandlimitedBall(circle, diameter=22.3, origin=p, value=1, mode='empty')
circle /= dip.Maximum(circle)
# Blend: img * (1-circle) + circle * color
img *= 1 - circle
img += circle * dip.Create0D([0,255,0]) # we make the circle green here
img.Show()
dip.ImageWrite(img, 'so.jpg')
(Note that the circle actually looks better without the JPEG compression artifacts.)
You could draw the circle directly in the image, but this function adds the circle values to the image, it doesn't attempt to blend, and so you'd get a much worse look for this particular application.
I'm very new to the image processing and object detection. I'd like to extract/identify the position and dimensions of teeth in the following image:
Here's what I've tried so far using OpenCV:
import cv2
import numpy as np
planets = cv2.imread('model.png', 0)
canny = cv2.Canny(planets, 70, 150)
circles = cv2.HoughCircles(canny,cv2.HOUGH_GRADIENT,1,40, param1=10,param2=16,minRadius=10,maxRadius=80)
circles = np.uint16(np.around(circles))
for i in circles[0,:]:
# draw the outer circle
cv2.circle(planets,(i[0],i[1]),i[2],(255,0,0),2)
# draw the center of the circle
cv2.circle(planets,(i[0],i[1]),2,(255,0,0),3)
cv2.imshow("HoughCirlces", planets)
cv2.waitKey()
cv2.destroyAllWindows()
This is what I get after applying canny filter:
This is the final result:
I don't know where to go from here. I'd like to get all of the teeth identified. How can I do that?
I'd really appreciate any help..
Note that the teeth-structure is more-or-less a parabola (upside-down). If you could somehow guess the parabolic shape that defines the centroids of those blobs (teeth), then your problem could be simplified to a reasonable extent. I have shown a red line that passes through the centers of the teeth.
I would suggest you to approach it as follows:
Binarize your image (background=0, else 1). You could use sklearn.preprocessing.binarize.
Calculate the centroid of all the non-zero pixels. This is the central blue circle in the image. Call this structure_centroid. See this: How to center the nonzero values within 2D numpy array?.
Make polar slices of the entire image, centered at the location of the structure_centroid. I have shown a cartoon image of such polar slices (triangular semi-transparent). Cover complete 360 degrees. See this: polarTransform library.
Determine the position of the centroid of the non-zero pixels for each of these polar slices. See these:
find the distance between a point and a curve python.
Find the minimum distance from a point to a curve.
The array containing these centroids gives you the locus (path) of the average location of the teeth. Call this centroid_path.
Run an elimination/selection algorithm on the circles you were able to detect, that are closest to the centroid_path. Use a threshold distance to drop the outliers.
This should give you a good approximation of the teeth with the circles.
I hope this helps.
I am using pygame to make a simple game. I am having issues with circle collisions. I am getting the following error:
"AttributeError: 'pygame.Rect' object has no attribute 'rect'"
Here is the particular code I am having issues with below:
if pygame.sprite.collide_circle(hero_circle, enemy_circle):
gameover()
Use pygame.mask to create a collision mesh for your objects and use the mesh to do collision detections.
In more detail:
Create an image file for both of your circles and set the bg color to something you will not use anywhere else.
Set that color to "transparent" in your image editor.
Import the images.
Create a mesh for them with pygame.mask and set it to make transparent pixels non-collidable.
Use the generated mask as your collision detection mesh.
PROFIT
(Technically this is just doing collision detection of a circle shaped area on a rectangle, but who cares!)
pygame.draw.rect()
draw a rectangle shape
rect(Surface, color, Rect, width=0) -> Rect
Draws a rectangular shape on the Surface. The given Rect is the area of the rectangle. The width argument is the thickness to draw the outer edge. If width is zero then the rectangle will be filled.
Keep in mind the Surface.fill() method works just as well for drawing filled rectangles. In fact the Surface.fill() can be hardware accelerated on some platforms with both software and hardware display modes.
The best way I've found to check circle collision detection is to calculate the distance between the center points of two circles. If the distance is less than the sum of the two circle's radii, then you've collided.
Just like how gmk said it but if your are using circles instead of rectangles, you should use this pygame function :
pygame.draw.circle(surface, color, center_point, radius, width)
This draws a circle on your surface (which would go in the surface area). Clearly the color requires a list of numbers (RGB anyone?). Your center_point decides the location of your circle since it will be the location of the center of your circle. The radius will need a number to set the radius of the circle (using the number like 25 will set your radius at 25 pixels/diameter at 50 pixels). the width section is optional as it sets the thickness of the perimeter of your circle (having 0 will have none at all). If you are not using circles, you should change your title... But anyways, I hope this helps you!
I am trying to draw a tilted ellipse in image draw. However, I am not sure how to define it, since while the scheme below would move the points, I think this would just squish the ellipse, not rotate it (also I think there is something slightly wrong with the transformation in any case). I am feeding the output of this function into the ellipse command and adding it to an existing picture, so any methods that would rotate the entire image are no good. OD is just a square offset to the coordinate center I am using.
def ellipsebound(major, minor, tilt=0, offset=0, angle=0):
#creates a bound for an ellispe, defined with tilt meaning to rotate the orthogonal axis and angle corresponds to rotating the ellipse position
angle = radians(angle)
tilt = radians(tilt)
box=(
1 + int(ceil((OD+offset*cos(angle)+(major*cos(tilt)+minor*sin(tilt)))/conv)),
1 + int(ceil((OD+offset*sin(angle)+(major*sin(tilt)-minor*cos(tilt)))/conv)),
int(ceil((2*OD-(OD-offset*cos(angle)-(major*cos(tilt)+minor*sin(tilt)))/conv))),
int(ceil((2*OD-(OD-offset*sin(angle)-(major*sin(tilt)-minor*cos(tilt)))/conv)))
) #create bounding box
return box
Does anyone know how to accomplish this?
It looks like the 'box' that is being used to draw the ellipse has no rotation associated with it. It is simply defined by the (left, top, right, bottom) extents.
One possible workaround (depending on what you need to do) is to draw the ellipse (sized correctly, but without the rotation) onto an intermediary image, use the image.rotate() method, and then paste it into your target image.
I hope that helps.