4x4_1000
4x4_1000 holds 1000 markers of
4×4 bits. In OpenCV it is
cv2.aruco.DICT_4X4_1000.
The numbers
| OpenCV name | cv2.aruco.DICT_4X4_1000 |
| Bits in a marker | 4 × 4 = 16 |
| Markers available | 1000, with IDs 0 to 999 |
| Printed width | 6 cells, border included |
| Bits the decoder repairs | 0 |
| Cell size on a 100 mm marker | 16.7 mm |
| Pixels wanted in the image | 72 (floor 24) |
| Range for a 100 mm marker | about 2.3 m |
Range assumes a camera 1920 px wide, 60 degree horizontal field of view, which is a focal length of about 1663 pixels, and a marker seen straight on.
No error correction
OpenCV reports a repair budget of zero bits for 4x4_1000. One misread cell cannot be recovered, so the marker is dropped or read as another ID. Use a dictionary with fewer markers, or one with more bits.
When to use it
Four bit markers have the widest cells at any printed size, so they read from the greatest distance and survive the most blur. They carry the least redundancy, so they are the easiest to misread. With 1000 markers it covers a large fleet of tagged objects, at the cost of a smaller repair budget.