helperTrackLocalMap error with Monocular SLAM

조회 수: 7 (최근 30일)
Sashamaru John
Sashamaru John 2020년 5월 15일
편집: cui,xingxing 2022년 11월 29일
Hi everyone,
I have run the Monocular SLAM (https://www.mathworks.com/help/vision/examples/monocular-visual-simultaneous-localization-and-mapping.html.) with Matlab 2020a, and I have tried some datasets, e.g., the TUM dataset in the tutorial and the Kitti dataset. How, I have got the following error.
Error using worldToImage
Expected worldPoints to be nonempty.
Error in worldToImage (line 83)
validateattributes(worldPoints, {'double', 'single'}, ...
Error in helperTrackLocalMap (line 63)
projectedPoints = worldToImage(intrinsics, R, t, localMapPoints);
Error in main (line 218)
helperTrackLocalMap(mapPointSet, vSetKeyFrames, mapPointsIdx, ...
I have found that this error is due to few keypoints. I did not change anything of the tutorial except changing the name of the helper function helperSURFFeatureExtractorFunction to helperExtractorFunction (helperExtractorFunction ). I was wondering if anyone else can run the tutorial successfully. Any help would be appreciated.
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Qu Cao
Qu Cao 2020년 5월 20일
Sashamaru, great to hear that tuning the parameter works!
Could you let me know which parameter of the two you changed?
Sashamaru John
Sashamaru John 2020년 5월 21일
Both work for me. Changing the first seems to be better than the second.

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답변 (1개)

Qu Cao
Qu Cao 2020년 8월 19일
Answer pasted from comments:
Please try tunning the parameters to see if it helps improve the robustness:
  • In helperIsKeyFrame, set the minimum number of tracked map points to a larger value, say 90;
  • In helperCreateNewMapPoints, change 'MaxRatio' to a smaller value, say 0.7
  댓글 수: 2
jose daniel hoyos giraldo
jose daniel hoyos giraldo 2021년 12월 27일
hello. Can you give me a hand improving the robustness, because I'm using a low resolution camera. Do you suggest change the line (in helperIsKeyFrame):
tooFewMapPoints = numel(mapPointsIndices) < 100;
for
tooFewMapPoints = numel(mapPointsIndices) < 500;
and the line:
tooFewTrackedPoints = numel(mapPointsIndices) < 0.9 * numPointsRefKeyFrame;
for
tooFewTrackedPoints = numel(mapPointsIndices) < 0.95 * numPointsRefKeyFrame;
Or similar?
On the other hand, in helperCreateNewMapPoints, u suggest use a smaller value of 'MaxRatio', but at mathworks it says "Use the max ratio for rejecting ambiguous matches. Increase this value to return more matches." (https://la.mathworks.com/help/vision/ref/matchfeatures.html).Then, if we have poor image quality and issues with a low number of points, why do you suggest decrease this value?.
Thanks for your help!
cui,xingxing
cui,xingxing 2022년 11월 29일
편집: cui,xingxing 2022년 11월 29일
I think this is more of an empirical threshold that is dynamically adjusted to your own images @jose daniel hoyos giraldo ,You can refer to the thresholds designed in the latest version of R2022b for the exact TUM dataset

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