dictionary = aruco.getPredefinedDictionary(aruco.DICT_5X5_100)
5X5 and 100 in aruco.DICT_5X5_100 represent:
- 5X5: Indicates that the ArUco mark is composed of a square grid with a size of 5x5 pixels.
- 100: Indicates that this dictionary contains 100 different ArUco tags. The aruco code dictionary contains multiple different binary markers. Each marker consists of a series of 0s and 1s and corresponds to a unique ID.
DICT_5X5_100 means that the dictionary uses 5x5 pixel markers, and there are a total of 100 markers with different IDs. So when we use aruco.getPredefinedDictionary(aruco.DICT_5X5_100), we get a predefined dictionary containing 100 IDs and each marker is 5x5 pixels in size. Other commonly used dictionaries include: - DICT_4X4_50: 4x4 pixels, 50 markers
- DICT_4X4_100: 4x4 pixels, 100 markers
- DICT_4X4_250: 4x4 pixels, 250 markers -
DICT_4X4_1000: 4x4 pixels, 1000 markers
- DICT_5X5_250: 5x5 pixels, 250 markers
- DICT_5X5_1000: 5x5 pixels, 1000 markers By specifying different dictionaries, we can generate and detect ArUco markers of different sizes and numbers.
The "number times several" in the aruco code represents the size of the square grid in each marker. For example, 5X5 in DICT_5X5_100 means: - Each ArUco marker is composed of 5x5 small square grids
- Each small grid is a pixel
- So the total size of each marker is 5 pixels x 5 pixels, that is, 5x5 pixels, for example For example, a 5x5 marker looks like this:
1 0 1 0 0 0 0 0 0 1 1 0 0 1 0 1 0 1 0 0 0 1 0 0 1
There are 5 rows and 5 columns here, a total of 5x5=25 grids (pixels). Similar: - The marker size in DICT_4X4_100 is 4 x 4 pixels
- The marker size in DICT_6X6_250 is 6 x 6 pixels so multiplied by several means that the marker is composed of a width and height of several pixels. This size will affect the size of the image space occupied by the marker, as well as the detection distance and accuracy. Generally speaking, the larger the size, the farther the detection distance is, but the larger the space it takes up. Therefore, it is necessary to choose an appropriate dictionary according to the actual situation.
The so-called multiplication of pixels is actually, for example, pixels 6*6, that is, except for the outer circle of black grids, there are 6*6 grids inside like a QR code, and the next 250 is how many IDs are included in the dictionary.