From 8c8b266b74779d47a1cac25f490841df8a1841e7 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Rafael=20Mu=C3=B1oz=20Salinas?= Date: Tue, 19 May 2026 08:18:29 +0200 Subject: [PATCH] Merge pull request #29034 from rmsalinas:fix-arucodictionary objdetect(aruco): fix maxCorrectionBits in predefined dictionaries #29034 This PR fixes the bugs in the creation of some dictionaries and standarizes its construction. ## Bugs 1. **DICT_ARUCO_MIP_36h12_DATA** was incorrectly assigned `maxCorrectionBits=12`, which is the intermarker distance. This was causing a high rate of false positives during detection, which is a significant problem. 2. **APRILTAG** dictionaries were incorrectly created with `maxCorrectionBits=0`, making it impossible to do error correction. ## Solution Given a intermarker distance X, the correct `maxCorrectionBits = X/2 - 1`. Thus, standardize the construction of Dictionaries as such. --- .../objdetect/src/aruco/aruco_dictionary.cpp | 50 +++++++++++-------- 1 file changed, 28 insertions(+), 22 deletions(-) diff --git a/modules/objdetect/src/aruco/aruco_dictionary.cpp b/modules/objdetect/src/aruco/aruco_dictionary.cpp index abacd9e4d1..b8e478fc85 100644 --- a/modules/objdetect/src/aruco/aruco_dictionary.cpp +++ b/modules/objdetect/src/aruco/aruco_dictionary.cpp @@ -266,36 +266,42 @@ Mat Dictionary::getBitsFromByteList(const Mat &byteList, int markerSize, int rot Dictionary getPredefinedDictionary(PredefinedDictionaryType name) { + // The maximum number of bits that can be corrected is theoretically (d-1)/2, + // where d is the minimum Hamming distance between any two codes in the dictionary. + // However, we use a more conservative limit (d/2)-1 to reduce the probability + // of false positives during detection. This formula is equivalent to the + // theoretical limit for even distances and stricter for odd distances. + // DictionaryData constructors calls // moved out of globals so construted on first use, which allows lazy-loading of opencv dll - static const Dictionary DICT_ARUCO_DATA = Dictionary(Mat(1024, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_ARUCO_BYTES), 5, 0); + static const Dictionary DICT_ARUCO_DATA = Dictionary(Mat(1024, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_ARUCO_BYTES), 5, (3-1)/2); - static const Dictionary DICT_4X4_50_DATA = Dictionary(Mat(50, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_4X4_1000_BYTES), 4, 1); - static const Dictionary DICT_4X4_100_DATA = Dictionary(Mat(100, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_4X4_1000_BYTES), 4, 1); - static const Dictionary DICT_4X4_250_DATA = Dictionary(Mat(250, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_4X4_1000_BYTES), 4, 1); - static const Dictionary DICT_4X4_1000_DATA = Dictionary(Mat(1000, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_4X4_1000_BYTES), 4, 0); + static const Dictionary DICT_4X4_50_DATA = Dictionary(Mat(50, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_4X4_1000_BYTES), 4, (4-1)/2); + static const Dictionary DICT_4X4_100_DATA = Dictionary(Mat(100, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_4X4_1000_BYTES), 4, (3-1)/2); + static const Dictionary DICT_4X4_250_DATA = Dictionary(Mat(250, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_4X4_1000_BYTES), 4, (3-1)/2); + static const Dictionary DICT_4X4_1000_DATA = Dictionary(Mat(1000, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_4X4_1000_BYTES), 4, (2-1)/2); - static const Dictionary DICT_5X5_50_DATA = Dictionary(Mat(50, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_5X5_1000_BYTES), 5, 3); - static const Dictionary DICT_5X5_100_DATA = Dictionary(Mat(100, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_5X5_1000_BYTES), 5, 3); - static const Dictionary DICT_5X5_250_DATA = Dictionary(Mat(250, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_5X5_1000_BYTES), 5, 2); - static const Dictionary DICT_5X5_1000_DATA = Dictionary(Mat(1000, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_5X5_1000_BYTES), 5, 2); + static const Dictionary DICT_5X5_50_DATA = Dictionary(Mat(50, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_5X5_1000_BYTES), 5, (8-1)/2); + static const Dictionary DICT_5X5_100_DATA = Dictionary(Mat(100, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_5X5_1000_BYTES), 5, (7-1)/2); + static const Dictionary DICT_5X5_250_DATA = Dictionary(Mat(250, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_5X5_1000_BYTES), 5, (6-1)/2); + static const Dictionary DICT_5X5_1000_DATA = Dictionary(Mat(1000, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_5X5_1000_BYTES), 5, (5-1)/2); - static const Dictionary DICT_6X6_50_DATA = Dictionary(Mat(50, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_6X6_1000_BYTES), 6, 6); - static const Dictionary DICT_6X6_100_DATA = Dictionary(Mat(100, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_6X6_1000_BYTES), 6, 5); - static const Dictionary DICT_6X6_250_DATA = Dictionary(Mat(250, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_6X6_1000_BYTES), 6, 5); - static const Dictionary DICT_6X6_1000_DATA = Dictionary(Mat(1000, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_6X6_1000_BYTES), 6, 4); + static const Dictionary DICT_6X6_50_DATA = Dictionary(Mat(50, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_6X6_1000_BYTES), 6, (13-1)/2); + static const Dictionary DICT_6X6_100_DATA = Dictionary(Mat(100, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_6X6_1000_BYTES), 6, (12-1)/2); + static const Dictionary DICT_6X6_250_DATA = Dictionary(Mat(250, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_6X6_1000_BYTES), 6, (11-1)/2); + static const Dictionary DICT_6X6_1000_DATA = Dictionary(Mat(1000, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_6X6_1000_BYTES), 6, (9-1)/2); - static const Dictionary DICT_7X7_50_DATA = Dictionary(Mat(50, (7 * 7 + 7) / 8, CV_8UC4, (uchar*)DICT_7X7_1000_BYTES), 7, 9); - static const Dictionary DICT_7X7_100_DATA = Dictionary(Mat(100, (7 * 7 + 7) / 8, CV_8UC4, (uchar*)DICT_7X7_1000_BYTES), 7, 8); - static const Dictionary DICT_7X7_250_DATA = Dictionary(Mat(250, (7 * 7 + 7) / 8, CV_8UC4, (uchar*)DICT_7X7_1000_BYTES), 7, 8); - static const Dictionary DICT_7X7_1000_DATA = Dictionary(Mat(1000, (7 * 7 + 7) / 8, CV_8UC4, (uchar*)DICT_7X7_1000_BYTES), 7, 6); + static const Dictionary DICT_7X7_50_DATA = Dictionary(Mat(50, (7 * 7 + 7) / 8, CV_8UC4, (uchar*)DICT_7X7_1000_BYTES), 7, (19-1)/2); + static const Dictionary DICT_7X7_100_DATA = Dictionary(Mat(100, (7 * 7 + 7) / 8, CV_8UC4, (uchar*)DICT_7X7_1000_BYTES), 7, (18-1)/2); + static const Dictionary DICT_7X7_250_DATA = Dictionary(Mat(250, (7 * 7 + 7) / 8, CV_8UC4, (uchar*)DICT_7X7_1000_BYTES), 7, (17-1)/2); + static const Dictionary DICT_7X7_1000_DATA = Dictionary(Mat(1000, (7 * 7 + 7) / 8, CV_8UC4, (uchar*)DICT_7X7_1000_BYTES), 7, (14-1)/2); - static const Dictionary DICT_APRILTAG_16h5_DATA = Dictionary(Mat(30, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_APRILTAG_16h5_BYTES), 4, 0); - static const Dictionary DICT_APRILTAG_25h9_DATA = Dictionary(Mat(35, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_APRILTAG_25h9_BYTES), 5, 0); - static const Dictionary DICT_APRILTAG_36h10_DATA = Dictionary(Mat(2320, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_APRILTAG_36h10_BYTES), 6, 0); - static const Dictionary DICT_APRILTAG_36h11_DATA = Dictionary(Mat(587, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_APRILTAG_36h11_BYTES), 6, 0); + static const Dictionary DICT_APRILTAG_16h5_DATA = Dictionary(Mat(30, (4 * 4 + 7) / 8, CV_8UC4, (uchar*)DICT_APRILTAG_16h5_BYTES), 4, (5-1)/2); + static const Dictionary DICT_APRILTAG_25h9_DATA = Dictionary(Mat(35, (5 * 5 + 7) / 8, CV_8UC4, (uchar*)DICT_APRILTAG_25h9_BYTES), 5, (9-1)/2); + static const Dictionary DICT_APRILTAG_36h10_DATA = Dictionary(Mat(2320, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_APRILTAG_36h10_BYTES), 6, (10-1)/2); + static const Dictionary DICT_APRILTAG_36h11_DATA = Dictionary(Mat(587, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_APRILTAG_36h11_BYTES), 6, (11-1)/2); - static const Dictionary DICT_ARUCO_MIP_36h12_DATA = Dictionary(Mat(250, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_ARUCO_MIP_36h12_BYTES), 6, 12); + static const Dictionary DICT_ARUCO_MIP_36h12_DATA = Dictionary(Mat(250, (6 * 6 + 7) / 8, CV_8UC4, (uchar*)DICT_ARUCO_MIP_36h12_BYTES), 6, (12-1)/2); switch(name) {