Fiducial detection system
View Patent ↗A new fiducial design allows having thousands of different codes. These fiducials are printed on a standard black-and-white (or color) printer and easily could be mounted on a walls, ceiling and objects in a room. The design includes “solid” outside mono-color ring and 2-D dense inside coding scheme. Image processing algorithms are implemented in Smart Camera with a built-in DSP to run all required image-processing tasks. A tracking system implementation includes an inertial measurement unit and one outward-looking wide-angle Smart Camera with possible extensions to number of stationary inward-looking cameras. The system operates in various real-world lighting conditions without any user intervention due to homomorphic image processing processes for extracting fiducials in the presence of very non-uniform lighting.
1. A fiducial mark for detection by a camera comprising:
a circular outer perimeter; and
a pattern of contrasting regions on an inside of the outer perimeter that is not symmetrical about a central point of the fiducial mark, and that identifies an identity code.
2. The fiducial mark of claim 1 further comprising a two dimensional (2D) array of encoding areas, each of the encoding areas having a color selected from a set of N colors, and having approximately equal sizes.
3. The fiducial mark of claim 2 further comprising features for establishing a reference frame for reading the patterns.
4. The fiducial mark of claim 3 in which the features comprise:
a feature used to establish an origin; and
features used to establish an x-axis and y-axis positioning.
5. The fiducial mark of claim 2 in which the perimeter is a single color.
6. The fiducial mark of claim 5 in which the color is black.
7. The fiducial mark of claim 6 in which the encoding areas inside the circular outer perimeter are contiguous with the circular outer ring to segment as one large blob.
8. The fiducial mark of claim 7 further comprising one or more small blobs inside the circular outer perimeter designated as indexing features.
9. The fiducial mark of claim 1 in which the perimeter and the patterns have contrasting colors.
10. A method for finding a centroid of an outer rim of a fiducial comprising:
capturing an image of the fiducial;
filling an interior of the fiducial image to match a color of the outer rim resulting in one solid ellipse-like shape; and
calculating the centroid of the one solid ellipse-like shape.
11. The method of claim 10 in which capturing the image further comprises using a logarithm of the image for contrast enhancement.
12. A method comprising:
determining a centroid of a framing object and all interior objects of a fiducial image; and
calculating a centroid of a virtual filled object using a formula for the centroid of a combination object.
13. A method of detecting fiducial marks comprising:
capturing an image of a fiducial mark, the fiducial mark comprising a circular outer perimeter, a pattern of contrasting regions on an inside of the outer perimeter that is not symmetrical about a central point of the fiducial mark, and that identifies an identity code, a two dimensional (2D) array of encoding areas, each of the encoding areas having a color selected from a set of N colors, and having approximately equal sizes and features for establishing a reference frame for reading the patterns;
determining an origin of the image from a first feature; and
determining an x-axis and a y-axis position of the image from second features.
14. The method of claim 13 in which capturing further comprises using a logarithm of the image for contrast enhancement.
15. A hybrid tracking system comprising:
a camera for capturing an image;
an inertial measurement unit; and
a sensor fusion core including a means for detecting a fiducial within the image.
16. The system of claim 15 in which the fiducial comprises:
a circular outer perimeter;
patterns on an inside of the outer perimeter for reading an identity code including higher information density per area than a pattern of concentric rings,
a two dimensional (2D) array of encoding areas, each of the encoding areas having a color selected from a set of N colors, and having approximately equal sizes; and
features for establishing a reference frame for reading the patterns.
17. The system of claim 16 in which the means for detecting the fiducial comprises:
determining an origin of the fiducial from a first feature; and
determining an x-axis position of the fiducial from second features.
18. The system of claim 15 further comprising a cluster of cameras.
19. A two-dimensional (2D) fiducial for image processing comprising:
an outer ring of 1 u width;
two data rings, each data ring having a 1 u width; and
an inner ring with 1 u width, wherein u is one length unit.
20. The fiducial of claim 19 in which the outer ring is colored black.
21. The fiducial of claim 19 in which the inner ring comprises a black circle with a white eye in a center.
22. The fiducial of claim 21 in which the white eye has a diameter of ⅜ u.
23. The fiducial of claim 19 in which each of the data rings comprises eight sectors with 45° degrees for each sector.
24. The fiducial of claim 23 in which the eight sectors comprise:
five sectors containing data cells;
two sectors colored white with a ⅜ u black eye inside; and
one sector colored black, the black colored sector positioned between the two white sectors and guaranteeing connectivity of all black color into a single blob.
25. The fiducial of claim 24 in which the two sectors are located 1⅞ u from the center.
26. An image processing target comprising:
a black colored outer ring of 1 u width;
two data rings, each data ring having a 1 u width and including eight sectors with 45° for each sector; and
an inner ring of 1 u width comprising a black circle with a white eye in a center.
27. The target of claim 26 in which the eight sectors comprise:
five sectors containing data cells;
two sectors colored white with a ⅜ u black eye inside; and
one sector colored black, the black colored sector positioned between the two white sectors and guaranteeing connectivity of all black color into a single blob.
28. An image processing system for a wearable vision-inertial self tracker comprising:
an inertial measurement unit (IMU);
a sensor fusion core (SFC) including means for acquiring, tracking and tracquisitioning a two-dimensional (2D) bar-code fiducial; and
a smart camera device.
29. The system of claim 28 further comprising a link from the sensor fusion core to a augmented reality (AR) system.
30. The system of claim 28 further comprising a link from the sensor fusion core to a robot.
31. A two dimensional (2D) fiducial design for image processing comprising:
a sequence of concentric rings, each of the rings including a plurality of mono-colored information sectors, each sector being of approximately a same size such that inner rings have less sectors than outer rings.
32. The design of claim 31 in which a subset of the sectors is reserved for connectivity of all black areas in a blob.
33. The design of claim 31 in which a subset of the sectors is reserved for positional information.