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I'm trying to detect the location of a fingertip from an image. I've been able to crop out a region in the image where it must have a fingertip, and extract the edges using Canny Edge Detector. However I'm stuck. Since my project description says I can't use the skin color for detection, I cannot find the exact contour of the finger, and will have to try to separate the fingertip with edges alone. Right now I'm thinking since the finger has a curved arch shape/letter U shape, maybe that could be used for detection. But since it has to be rotation/scale invariant, most algorithms I found so far are not up to it. Does anyone have an idea of how to do this? Thanks for anyone that responds!
This is the result I have now. I want to put a bounding box around the index fingertip, or the highest fingertip, whichever is the easiest.
You may view the tip of U as a corner, and try corner detection method such as the Foerstner Algorithm that will position of a corner with sub-pixel accuracy, and Haris corner detector which has implementation included in the feature2D class in opencv.
There is a very clear and straighforward lecture on Haris corner detector that I would like to share with you.
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I would like to know how can I approach my given problem: removing petiole from a leaf, with very little to none effects to the leaf.
From research, people tried using morphological operations like top-hat to enhance and remove the petiole afterwards, but in some cases this doesn't work so well, detecting in addition peaks from the leaf (example below).
I will try also segmentation based on HSV color space, but i will very much appreciate an idea for BGR space.
From left to right (input image, contour found, morphological applied with a kernel size structuring element which depends for every leaf species)
I am using OpenCV with C++.
example problem petiole detection
As mentioned in the comments I was curious to try this out myself.
And this is what I got:
I used the distance transform, but the final solution does not appear so perfect. I have the code in python if you would like.
CODE:
dist_transform = cv2.distanceTransform(thresh1,cv2.DIST_L2,5)
ret, stalk = cv2.threshold(dist_transform,0.095*dist_transform.max(),255,0)
stalk = np.uint8(stalk)
cv2.imshow('stalk_removed.jpg',stalk)
Where thresh1 is the binary image of the leaf.
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So my problem, as I said in the title is that I have an image that is in an perspective view and I to transform it into the orthographic view.
But as far as I can understand this example :
the distance from the camera to the NearClip plane and to the FarClip plane is required.
I was wondering if I'm going completly wrong and if there is a way to accomplish that without knowing those distances?
If yes, I Suppose it's something easy such as a matrix multiplication, but after few hours of research, I turn to you searchin any help that can come...
Thanks a lot!
Best regards!
EDIT : I will explain the context, maybe it can helps.
I have a Fish-eye camera that took a panoramic picture (like below, for example)
And my final goal is to create 6 cubics (6 image that corresponde to the up, the down, right, left, front and back of a cube if you're in the cube). So I tried to use the equirectangular projection to create a picture that contains the 6 cubics.
But the problem is that the fisheye take perspective view. So my 6 pictures are perspectives. And I want them to be ortho... :'(
No this is not possible without making several assumptions. Distances or object sizes..
Of course you don't have any informaton of what is behind your objects from your perspective. This information is not available even if you had the distances.
If that was possible there would be no need for 3d-imaging or telecentric lenses.
Of course you can also assume that your objects are spheres. Then you know what to add in your reconstruction but in general this is not viable.
This may be an old question, but the existing answer of "not possible" is not correct for pictures that are less extreme than the example. Photoshop has a Lens Correction tool, as does the free program Gimp. A tutorial for the Photoshop tool is at https://helpx.adobe.com/photoshop/using/correcting-image-distortion-noise.html#correct_lens_distortion_and_adjust_perspective showing it can be done through Choose Filter > Lens Correction. And though you would need to know specific measurements from the camera or scene to perfectly correct the image, you can get pretty close and use assumptions that some objects will have straight edges or certain lines will be parallel.
Gimp's tool is under Filters -> Distorts -> Lens Distortions, and some examples can be found at http://www.texturemate.com/content/how-easily-remove-lens-distortion-photos-using-gimp and there's a StackExchange answer for it at https://gamedev.stackexchange.com/questions/129415/converting-real-life-perspective-photos-into-orthographic-view-for-texture-creat
Neither of these may be extensive enough to un-distort an image from fisheye lenses, but these options are available to anyone who found this page and hopes to adjust an image with more common distortions.
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I have a landscape(generated via Perlin noise) and a ball. I want the ball to move along the geodesic(implementation of basic physics: gravitation, friction).
I thought to do raycast around the ball to the landscape, choose the lowest point and move the ball to this point, but it won't work in every case and it won't allow the ball to jump (with inertia).
So, what is the best way/algorithm to implement such feature?
P.S. I don't want to use any libraries.
It'll take some time, but it's not THAT hard, you need to calculate the ball's new position, ignoring the height field at all (only gravity & inertia) and then, after this step, you check for collisions (basic collision detection between sphere and triangle mesh), and if a collision is detected, generate the collision data and resolve it by applying an impulse OR force in the appropriate direction, using the motion direction and the collision normal direction. Now, if you never worked with collision detection before, it'll probably take you some extra time to learn the algorithms involved, like how to detect collision, how to generate the collision data (normal, penetration, etc).
You need to build your own physics library for this task which individual effort can take months. If you still don't want to export an external engine to your project, At least I suggest you to check open-source engines to see how they handle things.
I can suggest Bullet Physics for a start.
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Is it possible to create something like this in inkscape? I have been searching and trying for quite some time, but so far no results...
So what I am looking for is a gradient which follows the direction of the path it is applied to.
Gradient along a path http://coreldraw.com/cfs-filesystemfile.ashx/__key/CommunityServer.Components.PostAttachments/00.00.02.07.23/GradientBlend2.jpg
I am not aware of a solution that perfectly satisfies your needs however here is one approach to get close:
Draw a line, open the Fill and Stroke dialog and set the width of the stroke (Stroke style tab) to 50. Transform the stroke to a path (Path > Stroke to Path).
Fill the path with a linear gradient (Fill and Stroke dialog > Fill > Linear gradient) and choose any colours you like.
Select the node tool (F2) and a line will appear stretching the area of your shape (marked with an exclamation mark on the picture below). Adjusting this line may help you to fine tune the gradient (however, strictly speaking it will not follow the path but a rectangle defined by the start and end marker of the marked line)
This should work for simple shapes that do not reverse. Let me know if this is good enough or if you need more detailed instructions.
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I'm working on a graphics project trying to create an impossible cube in 3D. An impossible cube looks like that:
The trick behind this is two of the edges which are 'cut' and a picture taken from a specific angle to give the illusion of the impossibility.
Well I'm trying to make this but instead of a static image, I want to be able to animate it (rotate around) maintaining the impossible properties.
I have managed to make a cube in blender as you can see in the screenshot below:
I would like to hear your suggestions as to how I can achieve the desired effect. An idea would be to make transparent the portion of the edge that has an edge(or more) behind it, so that every time the camera angle changes, the transparent patch moves along.
It doesn't have to be done in Blender exclusively so any solutions in OpenGL etc are welcome.
To give you an idea of what the end result should be, this is a link to such an illustration:
3D Impossible Cube Illusion Animation
It's impossible (heh). Try to imagine rotating the cube so that the impossibly-in-front bit moves to the left. As soon as it would "cross" the current leftmost edge, the two properties of "it's in front" and "it's in the back" will not be possible to fulfill simultaneously.
If you have edge culling enabled, but clipping (depth-testing) disabled, and draw primitives in the right order, you should get the Escher cube without any need for cuts. This should be relatively easy to animate.