396 questions
0
votes
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answers
64
views
how to apply backward warp (pytorch's grid_sample) with forward optical flow?
I have been working on optical flow algorithms recently and have been using pytorch to apply the optical flow field.
I have noticed that most libraries have implemented only the backward warp function ...
- 1
0
votes
0
answers
35
views
Horizontal Opicalflow
I can get the X-axis (horizontal) flow through the following:
flow = cv2.calcOpticalFlowFarneback(
self.prev_gray, curr_gray, None,
pyr_scale=0.5, levels=8, winsize=3,
...
1
vote
1
answer
147
views
How to Extract Optical Flow from Videos with Indistinguishable Features?
Problem: I have videos from which I want to extract the optical flow, even though they do not have clear features to track.
Details:
I have a small channel through which I flow water. I add tracer ...
- 55
0
votes
1
answer
115
views
Lucas-Kanade optical flow - gradient calculation
I have implemented Lucas-Kanade method (per pixel version, not the one for features that is in OpenCV). However, I have a question regarding calculating gradients (dx, dy, dt). In a few ...
- 9,537
2
votes
1
answer
531
views
Issue with Hierarchical Lucas-Kanade method on Optical Flow
Issue with Hierarchical Lucas-Kanade method on optical flow
I am implementing the hierarchical Lucas-Kanade method in Python based on
this tutorial. However, when
applying the method to a rotating ...
- 2,025
1
vote
1
answer
494
views
NVIDIA optical flow algorithm producing vectors with unreasonably large magnitudes/directions
I made a simple test movie to play with the optical flow SDK. The movie is two textured rectangles, one stationary, the other moving from left to right and back.
Working on 8 bit greyscale, after ...
- 10.1k
-3
votes
1
answer
149
views
short2, 10 bit integer, 5 bit fraction, one sign bit
NVIDIA's Optical Flow library documentation states the flow vectors are "represented by a 32-bit value with each horizontal and vertical compoment being 16-bit value. The lowest 5 bits holding ...
- 10.1k
0
votes
0
answers
389
views
Farneback's optical flow implementation
I want to integrate Farneback's optical flow in my framework and I started with a Python prototype.
I tried to follow the steps described in this paper and I compared to OpenCV's output, but I get far ...
- 762
0
votes
0
answers
104
views
Opencv remap returns squeezed image rather than slightly offsetted
I have a "distort.png" image in which the "R,G" Channels holding motion vectors (Original Position offsetted by 10 pixels) I'm using remap to transform the image into the new ...
- 25.3k
0
votes
0
answers
43
views
How is it handled if the neighborhood of the image is outside the image?
when using cv.calcOpticalFlowFarneback, how is it handled if the neighborhood of the image is outside the image? Maybe, I think that is padding, which is correct? Also Where can I refer to understand ...
- 33
2
votes
0
answers
377
views
In Lucas-Kanade Optical Flow Method, what can be the maximum Euclidean Distance between tracked point pairs?
I am using Lucas-Kanade Optical Flow Method to track the points from one image to the next one. In OpenCV, there is an easy to use function:
void cv::calcOpticalFlowPyrLK (
InputArray ...
- 2,037
0
votes
0
answers
74
views
On computation of pyramidal optical flow
I have a question regarding the pyramid approach used in optical flow algorithms. Actually, the size of my memory does not allow me to store all the images in the pyramid, and I cannot average the ...
- 3
0
votes
1
answer
346
views
Is there a way to do background substraction on video of moving cameras? based on optical flow mainly?
My problem is: Now i can get the dense optical flow for the video. The object and background are moving at the same time due to the rotation of the camera, therefore both the target and backgroud have ...
- 11
1
vote
1
answer
926
views
I have calculated a flow field in Pytorch. How do I generate a remapped image using this?
I have used the RAFT model in pytorch to calculate optical flow between two frames. Here is the code for that:
noise_img = noise_img.to(device)
clean_img = clean_img.to(device)
...
- 180
1
vote
1
answer
421
views
How to find a threshold number in Optical Flow in Python OpenCV [closed]
Using optical flow, I am trying to detect the motion of a coil attached to a motor. When the motor starts, coil runs smoothly but sometimes it starts to vibrate. I need to detect this vibration. I am ...
- 7,436