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Fix initial guess for Cal3Bundler calibrate #775

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merged 6 commits into from
Jun 4, 2021
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Merged

Fix initial guess for Cal3Bundler calibrate #775

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9930952
Add Akshay's Cal3Bundler test
varunagrawal May 30, 2021
c252937
account for radial distortion in initial guess for `calibrate`
varunagrawal May 30, 2021
c2f4cc8
initialize with intrinsic coordinates which has radial distortion mod…
varunagrawal Jun 2, 2021
fb784ee
add all of Akshay's tests for default model
varunagrawal Jun 2, 2021
b844026
addressed comments and added an additional test
varunagrawal Jun 3, 2021
2d739dd
make rr and g as const
varunagrawal Jun 3, 2021
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10 changes: 4 additions & 6 deletions gtsam/geometry/Cal3Bundler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -96,19 +96,17 @@ Point2 Cal3Bundler::calibrate(const Point2& pi, OptionalJacobian<2, 3> Dcal,
OptionalJacobian<2, 2> Dp) const {
// Copied from Cal3DS2
// but specialized with k1, k2 non-zero only and fx=fy and s=0
double x = (pi.x() - u0_) / fx_, y = (pi.y() - v0_) / fx_;
const Point2 invKPi(x, y);

double px = (pi.x() - u0_) / fx_, py = (pi.y() - v0_) / fx_;
const Point2 invKPi(px, py);
Point2 pn;
double px = pi.x(), py = pi.y();

// iterate until the uncalibrate is close to the actual pixel coordinate
const int maxIterations = 10;
int iteration = 0;
do {
// initialize pn with distortion included
double rr = (px * px) + (py * py);
double g = (1 + k1_ * rr + k2_ * rr * rr);
const double rr = (px * px) + (py * py);
const double g = (1 + k1_ * rr + k2_ * rr * rr);
pn = invKPi / g;

if (distance2(uncalibrate(pn), pi) <= tol_) break;
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27 changes: 27 additions & 0 deletions gtsam/geometry/tests/testCal3Bundler.cpp
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Expand Up @@ -89,6 +89,33 @@ TEST(Cal3Bundler, DcalibrateDefault) {
CHECK(assert_equal(numerical2, Dp, 1e-5));
}

/* ************************************************************************* */
TEST(Cal3Bundler, DuncalibratePrincipalPoint) {
Cal3Bundler K(5, 0, 0, 2, 2);
Matrix Dcal, Dp;
Point2 actual = K.uncalibrate(p, Dcal, Dp);
Point2 expected(12, 17);
CHECK(assert_equal(expected, actual, 1e-7));
Matrix numerical1 = numericalDerivative21(uncalibrate_, K, p);
Matrix numerical2 = numericalDerivative22(uncalibrate_, K, p);
CHECK(assert_equal(numerical1, Dcal, 1e-7));
CHECK(assert_equal(numerical2, Dp, 1e-7));
}

/* ************************************************************************* */
TEST(Cal3Bundler, DcalibratePrincipalPoint) {
Cal3Bundler K(2, 0, 0, 2, 2);
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There’s also a global static variable by name K, just FYI in case you missed that. I don’t think it should cause any issues though.

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Yeah I know about that. The local scope will take precedence so it's all good.

Matrix Dcal, Dp;
Point2 pn(0.5, 0.5);
Point2 pi = K.uncalibrate(pn);
Point2 actual = K.calibrate(pi, Dcal, Dp);
CHECK(assert_equal(pn, actual, 1e-7));
Matrix numerical1 = numericalDerivative21(calibrate_, K, pi);
Matrix numerical2 = numericalDerivative22(calibrate_, K, pi);
CHECK(assert_equal(numerical1, Dcal, 1e-5));
CHECK(assert_equal(numerical2, Dp, 1e-5));
}

/* ************************************************************************* */
TEST(Cal3Bundler, Duncalibrate) {
Matrix Dcal, Dp;
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