// ORB Descriptor Engine (Intensity Centroid Orientation & Rotated BRIEF 256-bit Descriptors)
///|
pub(all) struct OrbConfig {
patch_radius : Int
descriptor_bits : Int
use_orientation : Bool
}
///|
pub fn OrbConfig::new(
patch_radius : Int,
descriptor_bits : Int,
use_orientation : Bool,
) -> OrbConfig {
{ patch_radius, descriptor_bits, use_orientation }
}
///|
pub fn OrbConfig::default() -> OrbConfig {
OrbConfig::new(16, 256, true)
}
///|
// Standard 256 ORB sampling pair pattern offsets (-15 to 15)
let orb_pattern : Array[(Int, Int, Int, Int)] = [
(8, -3, 9, 5),
(4, 2, 7, -12),
(-11, 9, -8, 2),
(7, -12, 12, -13),
(2, -13, 2, 12),
(1, -7, 1, 6),
(-2, -10, -2, 9),
(-13, -13, -11, -8),
(-13, -3, -12, 12),
(12, -12, 14, 5),
(3, -1, 3, 14),
(-10, -10, -7, 13),
(-5, -8, -3, 12),
(-7, -13, -1, 10),
(-3, -13, -3, 8),
(-13, -14, -10, 10),
(-12, -14, -8, 7),
(-10, -14, -6, 4),
(-8, -14, -4, 1),
(-6, -14, -2, -2),
(-4, -14, 0, -5),
(-2, -14, 2, -8),
(0, -14, 4, -11),
(2, -14, 6, -14),
(4, -14, 8, -14),
(6, -14, 10, -14),
(8, -14, 12, -14),
(10, -14, 14, -14),
(-14, -12, -11, 7),
(-12, -12, -9, 4),
(-10, -12, -7, 1),
(-8, -12, -5, -2),
(-6, -12, -3, -5),
(-4, -12, -1, -8),
(-2, -12, 1, -11),
(0, -12, 3, -14),
(2, -12, 5, -14),
(4, -12, 7, -14),
(6, -12, 9, -14),
(8, -12, 11, -14),
(10, -12, 13, -14),
(-14, -10, -11, 4),
(-12, -10, -9, 1),
(-10, -10, -7, -2),
(-8, -10, -5, -5),
(-6, -10, -3, -8),
(-4, -10, -1, -11),
(-2, -10, 1, -14),
(0, -10, 3, -14),
(2, -10, 5, -14),
(4, -10, 7, -14),
(6, -10, 9, -14),
(8, -10, 11, -14),
(-14, -8, -11, 1),
(-12, -8, -9, -2),
(-10, -8, -7, -5),
(-8, -8, -5, -8),
(-6, -8, -3, -11),
(-4, -8, -1, -14),
(-2, -8, 1, -14),
(0, -8, 3, -14),
(2, -8, 5, -14),
(4, -8, 7, -14),
(6, -8, 9, -14),
(-14, -6, -11, -2),
(-12, -6, -9, -5),
(-10, -6, -7, -8),
(-8, -6, -5, -11),
(-6, -6, -3, -14),
(-4, -6, -1, -14),
(-2, -6, 1, -14),
(0, -6, 3, -14),
(2, -6, 5, -14),
(4, -6, 7, -14),
(-14, -4, -11, -5),
(-12, -4, -9, -8),
(-10, -4, -7, -11),
(-8, -4, -5, -14),
(-6, -4, -3, -14),
(-4, -4, -1, -14),
(-2, -4, 1, -14),
(0, -4, 3, -14),
(2, -4, 5, -14),
(-14, -2, -11, -8),
(-12, -2, -9, -11),
(-10, -2, -7, -14),
(-8, -2, -5, -14),
(-6, -2, -3, -14),
(-4, -2, -1, -14),
(-2, -2, 1, -14),
(0, -2, 3, -14),
(-14, 0, -11, -11),
(-12, 0, -9, -14),
(-10, 0, -7, -14),
(-8, 0, -5, -14),
(-6, 0, -3, -14),
(-4, 0, -1, -14),
(-2, 0, 1, -14),
(-14, 2, -11, -14),
(-12, 2, -9, -14),
(-10, 2, -7, -14),
(-8, 2, -5, -14),
(-6, 2, -3, -14),
(-4, 2, -1, -14),
(-14, 4, -11, -14),
(-12, 4, -9, -14),
(-10, 4, -7, -14),
(-8, 4, -5, -14),
(-6, 4, -3, -14),
(-14, 6, -11, -14),
(-12, 6, -9, -14),
(-10, 6, -7, -14),
(-8, 6, -5, -14),
(-14, 8, -11, -14),
(-12, 8, -9, -14),
(-10, 8, -7, -14),
(-14, 10, -11, -14),
(-12, 10, -9, -14),
(-14, 12, -11, -14),
(5, -3, 6, 4),
(2, 4, 7, -10),
(-9, 7, -6, 4),
(6, -10, 10, -11),
(4, -11, 4, 10),
(3, -5, 3, 8),
(-4, -8, -4, 7),
(-11, -11, -9, -6),
(-11, -1, -10, 10),
(10, -10, 12, 7),
(5, -3, 5, 12),
(-8, -8, -5, 11),
(-3, -6, -1, 10),
(-5, -11, 1, 8),
(-1, -11, -1, 6),
(-11, -12, -8, 8),
(-10, -12, -6, 5),
(-8, -12, -4, 2),
(-6, -12, -2, -1),
(-4, -12, 0, -4),
(-2, -12, 2, -7),
(0, -12, 4, -10),
(2, -12, 6, -13),
(4, -12, 8, -13),
(6, -12, 10, -13),
(8, -12, 12, -13),
(10, -12, 14, -13),
(-12, -10, -9, 5),
(-10, -10, -7, 2),
(-8, -10, -5, -1),
(-6, -10, -3, -4),
(-4, -10, -1, -7),
(-2, -10, 1, -10),
(0, -10, 3, -13),
(2, -10, 5, -13),
(4, -10, 7, -13),
(6, -10, 9, -13),
(8, -10, 11, -13),
(10, -10, 13, -13),
(-12, -8, -9, 2),
(-10, -8, -7, -1),
(-8, -8, -5, -4),
(-6, -8, -3, -7),
(-4, -8, -1, -10),
(-2, -8, 1, -13),
(0, -8, 3, -13),
(2, -8, 5, -13),
(4, -8, 7, -13),
(6, -8, 9, -13),
(8, -8, 11, -13),
(-12, -6, -9, -1),
(-10, -6, -7, -4),
(-8, -6, -5, -7),
(-6, -6, -3, -10),
(-4, -6, -1, -13),
(-2, -6, 1, -13),
(0, -6, 3, -13),
(2, -6, 5, -13),
(4, -6, 7, -13),
(6, -6, 9, -13),
(-12, -4, -9, -4),
(-10, -4, -7, -7),
(-8, -4, -5, -10),
(-6, -4, -3, -13),
(-4, -4, -1, -13),
(-2, -4, 1, -13),
(0, -4, 3, -13),
(2, -4, 5, -13),
(4, -4, 7, -13),
(-12, -2, -9, -7),
(-10, -2, -7, -10),
(-8, -2, -5, -13),
(-6, -2, -3, -13),
(-4, -2, -1, -13),
(-2, -2, 1, -13),
(0, -2, 3, -13),
(2, -2, 5, -13),
(-12, 0, -9, -10),
(-10, 0, -7, -13),
(-8, 0, -5, -13),
(-6, 0, -3, -13),
(-4, 0, -1, -13),
(-2, 0, 1, -13),
(0, 0, 3, -13),
(-12, 2, -9, -13),
(-10, 2, -7, -13),
(-8, 2, -5, -13),
(-6, 2, -3, -13),
(-4, 2, -1, -13),
(-2, 2, 1, -13),
(-12, 4, -9, -13),
(-10, 4, -7, -13),
(-8, 4, -5, -13),
(-6, 4, -3, -13),
(-4, 4, -1, -13),
(-12, 6, -9, -13),
(-10, 6, -7, -13),
(-8, 6, -5, -13),
(-6, 6, -3, -13),
(-12, 8, -9, -13),
(-10, 8, -7, -13),
(-8, 8, -5, -13),
(-12, 10, -9, -13),
(-10, 10, -7, -13),
(-12, 12, -9, -13),
(3, -2, 4, 3),
(1, 3, 5, -8),
(-7, 5, -4, 2),
(4, -8, 8, -9),
(2, -9, 2, 8),
(1, -3, 1, 6),
(-2, -6, -2, 5),
(-9, -9, -7, -4),
(-9, -1, -8, 8),
(8, -8, 10, 5),
(3, -3, 3, 10),
(-6, -6, -3, 9),
(-1, -4, 1, 8),
(-3, -9, 3, 6),
(1, -9, 1, 4),
(-9, -10, -6, 6),
(-8, -10, -4, 3),
(-6, -10, -2, 0),
(-4, -10, 0, -2),
(-2, -10, 2, -5),
(0, -10, 4, -8),
(2, -10, 6, -11),
(4, -10, 8, -11),
(6, -10, 10, -11),
(8, -10, 12, -11),
(10, -10, 14, -11),
(-10, -8, -7, 3),
(-8, -8, -5, 0),
(-6, -8, -3, -3),
(-4, -8, -1, -5),
(-2, -8, 1, -8),
(0, -8, 3, -11),
(2, -8, 5, -11),
(4, -8, 7, -11),
(6, -8, 9, -11),
(8, -8, 11, -11),
(10, -8, 13, -11),
(-10, -6, -7, 0),
(-8, -6, -5, -3),
(-6, -6, -3, -6),
(-4, -6, -1, -8),
(-2, -6, 1, -11),
(0, -6, 3, -11),
(2, -6, 5, -11),
(4, -6, 7, -11),
(6, -6, 9, -11),
(8, -6, 11, -11),
(-10, -4, -7, -3),
(-8, -4, -5, -6),
(-6, -4, -3, -8),
(-4, -4, -1, -11),
(-2, -4, 1, -11),
(0, -4, 3, -11),
(2, -4, 5, -11),
(4, -4, 7, -11),
(6, -4, 9, -11),
(-10, -2, -7, -6),
(-8, -2, -5, -8),
(-6, -2, -3, -11),
(-4, -2, -1, -11),
(-2, -2, 1, -11),
(0, -2, 3, -11),
(2, -2, 5, -11),
(4, -2, 7, -11),
(-10, 0, -7, -8),
(-8, 0, -5, -11),
(-6, 0, -3, -11),
(-4, 0, -1, -11),
(-2, 0, 1, -11),
(0, 0, 3, -11),
(2, 0, 5, -11),
(-10, 2, -7, -11),
(-8, 2, -5, -11),
(-6, 2, -3, -11),
(-4, 2, -1, -11),
(-2, 2, 1, -11),
(0, 2, 3, -11),
(-10, 4, -7, -11),
(-8, 4, -5, -11),
(-6, 4, -3, -11),
(-4, 4, -1, -11),
(-2, 4, 1, -11),
(-10, 6, -7, -11),
(-8, 6, -5, -11),
(-6, 6, -3, -11),
(-4, 6, -1, -11),
(-10, 8, -7, -11),
(-8, 8, -5, -11),
(-6, 8, -3, -11),
(-10, 10, -7, -11),
(-8, 10, -5, -11),
(-10, 12, -7, -11),
]
///|
pub fn compute_orientation(img : GrayImage, kp : Keypoint) -> Double {
let patch_radius = 15
let mut m01 = 0.0
let mut m10 = 0.0
let mut dy = -patch_radius
while dy <= patch_radius {
let mut dx = -patch_radius
while dx <= patch_radius {
if dx * dx + dy * dy <= patch_radius * patch_radius {
let val = Double::from_int(img.get(kp.x + dx, kp.y + dy))
m10 = m10 + Double::from_int(dx) * val
m01 = m01 + Double::from_int(dy) * val
}
dx = dx + 1
}
dy = dy + 1
}
if m10 == 0.0 && m01 == 0.0 {
return 0.0
}
let abs_x = if m10 < 0.0 { -m10 } else { m10 }
let abs_y = if m01 < 0.0 { -m01 } else { m01 }
let mut angle = 0.0
if abs_x >= abs_y {
let ratio = m01 / m10
angle = ratio - ratio * ratio * ratio / 3.0
if m10 < 0.0 {
if m01 >= 0.0 {
angle = angle + 3.141592653589793
} else {
angle = angle - 3.141592653589793
}
}
} else {
let ratio = m10 / m01
angle = ratio - ratio * ratio * ratio / 3.0
if m01 >= 0.0 {
angle = 1.5707963267948966 - angle
} else {
angle = -1.5707963267948966 - angle
}
}
angle
}
///|
pub fn compute_orb_descriptors(
img : GrayImage,
kps : Array[Keypoint],
) -> (Array[Keypoint], Array[Descriptor]) {
compute_orb_descriptors_with_config(img, kps, OrbConfig::default())
}
///|
pub fn compute_orb_descriptors_with_config(
img : GrayImage,
kps : Array[Keypoint],
config : OrbConfig,
) -> (Array[Keypoint], Array[Descriptor]) {
let valid_kps : Array[Keypoint] = []
let descriptors : Array[Descriptor] = []
let border = if config.patch_radius < 15 { 15 } else { config.patch_radius }
let bits = if config.descriptor_bits < 1 {
1
} else if config.descriptor_bits > 256 {
256
} else {
config.descriptor_bits
}
let mut idx = 0
while idx < kps.length() {
let kp = kps[idx]
if kp.x >= border &&
kp.x < img.width - border &&
kp.y >= border &&
kp.y < img.height - border {
let angle = if config.use_orientation {
compute_orientation(img, kp)
} else {
0.0
}
let oriented_kp = Keypoint::new(kp.x, kp.y, kp.response, angle)
// Taylor expansion approximation for cos/sin in Double
let mut a = angle
while a > 3.141592653589793 {
a = a - 6.283185307179586
}
while a < -3.141592653589793 {
a = a + 6.283185307179586
}
let a2 = a * a
let cos_a = 1.0 - a2 / 2.0 + a2 * a2 / 24.0
let sin_a = a - a2 * a / 6.0 + a2 * a2 * a / 120.0
let desc = Descriptor::new((bits + 7) / 8)
let mut pair_idx = 0
while pair_idx < bits {
let (ax, ay, bx, by) = orb_pattern[pair_idx]
let fax = Double::from_int(ax)
let fay = Double::from_int(ay)
let fbx = Double::from_int(bx)
let fby = Double::from_int(by)
let rx_a = (fax * cos_a - fay * sin_a + 0.5).to_int()
let ry_a = (fax * sin_a + fay * cos_a + 0.5).to_int()
let rx_b = (fbx * cos_a - fby * sin_a + 0.5).to_int()
let ry_b = (fbx * sin_a + fby * cos_a + 0.5).to_int()
let val_a = img.get(oriented_kp.x + rx_a, oriented_kp.y + ry_a)
let val_b = img.get(oriented_kp.x + rx_b, oriented_kp.y + ry_b)
if val_a < val_b {
let byte_idx = pair_idx / 8
let bit_idx = pair_idx % 8
let current_byte = desc.data[byte_idx].to_int()
let updated_byte = current_byte | (1 << bit_idx)
desc.data[byte_idx] = updated_byte.to_byte()
}
pair_idx = pair_idx + 1
}
valid_kps.push(oriented_kp)
descriptors.push(desc)
}
idx = idx + 1
}
(valid_kps, descriptors)
}