19
votes
Accepted
OpenGL - Detection of edges
Generally edge detection boils down to detect areas of the image with high gradient value.
In our case we can crudely see the gradient as the derivative of the image function, therefore the ...
- 2,518
11
votes
Accepted
OpenGL GLSL - Sobel Edge Detection Filter
The best results strongly depend on your use case. They also depend on what effect you want to achieve. Sobel is just an edge detection filter: the edges will depend on the input signal, choosing that ...
- 4,380
4
votes
Accepted
Which method for detecting edges of white object on white background?
It's quite difficult. There is so little contrast, even the JPEG compression artifacts have more contrast than the object on the background.
You would require a highly specialized deblock filter to ...
- 176
4
votes
Accepted
How would I create a virtual cabling system?
The shape you’re trying to draw is called a catenary: it’s the shape that a cable/cord of constant density takes when supported at each end. You’ll have to do some research to find a parametric ...
- 2,122
4
votes
Accepted
Controlling Sobel edge thickness
I've done this 2 different ways in the past:
Apply a pre-blur to the image before running the Sobel operator on it. This will have the side effect of getting rid of any noise that's smaller than the ...
- 3,391
4
votes
OpenGL - Detection of edges
Just in case anyone elso also needs to detect edges:
Here is a nice article how to display a wireframe and this article explains how to show only the edges.
- 601
3
votes
Accepted
How to crop with edge-detection using imagemagick
Try -trim instead of -shave:
convert original.png -trim trimmed.png
See the docs for this ...
- 724
3
votes
Accepted
How can I detect edges between different colours of the same brightness?
I think you can convert from the RGB space to the HSV one, or whatever color space has the HUE in a single channel.
Take the HUE channel, and make the edge detection on that one.
Here a simple ...
- 610
2
votes
How can I detect edges between different colours of the same brightness?
Color difference is a difference in brightness, in some color channel. So while the sum of individual channels stay the same, there is a intensity difference if there is a color difference.
Now the ...
- 8,367
2
votes
Rounding a corner formed by Arc and Line
I suppose you want an arc of C0 and C1 continuity between the line and an arc.
As illustrated above, you already have a vertex A which is the intersection of an edge and an arc of which the center ...
- 27
2
votes
Accepted
Is it better to blur the input or output of an edge detection shader for noise reduction?
Standard blur removes high frequency content from the signal, whereas edge detection usually look into high frequency to detect edges. Be careful on how much blurring to apply to ensure that you don't ...
- 371
2
votes
GLSL - Merge two textures
The simplest solution would be just a multiplication, which would give black edges:
combinedColor = sceneColor * edgeRGB.r;
For more control I would suggest ...
- 4,380
1
vote
HalfEdge: How to get list of all faces from one face
Observe that you can construct another graph by connecting the centroids of faces with centroids of adjacent faces. This is known as the dual. The edges of the graph between the centroids can be ...
- 1,089
1
vote
Half-Edge Data Structure with holes
The cube-like mesh shown in the images is a non-manifold mesh. Officially half edge data structures do not support such a topology. However, this case can be supported by continuing the boundary half ...
- 1,089
1
vote
Sobel edge detection line thickness
The edge between the sphere and the background is actually the one that is incorrect; you need to initialize your normal texture with a unit normal to get correct results.
The two pixels thickness is ...
- 4,380
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