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Merge pull request #20564 from AleksandrPanov:update_kalman_sample

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Update kalman sample

* updated view and comments, fixed dims

* updated view and comments, added statePost
This commit is contained in:
Alexander Panov 2021-08-20 13:57:05 +03:00 committed by GitHub
parent a9817e9127
commit d6306f8ccb
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2 changed files with 83 additions and 72 deletions
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58
samples/cpp/kalman.cpp
View File

@ -1,6 +1,6 @@
#include "opencv2/video/tracking.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/core/cvdef.h"
#include <stdio.h>
using namespace cv;
@ -14,15 +14,19 @@ static void help()
{
printf( "\nExample of c calls to OpenCV's Kalman filter.\n"
" Tracking of rotating point.\n"
" Rotation speed is constant.\n"
" Point moves in a circle and is characterized by a 1D state.\n"
" state_k+1 = state_k + speed + process_noise N(0, 1e-5)\n"
" The speed is constant.\n"
" Both state and measurements vectors are 1D (a point angle),\n"
" Measurement is the real point angle + gaussian noise.\n"
" The real and the estimated points are connected with yellow line segment,\n"
" the real and the measured points are connected with red line segment.\n"
" Measurement is the real state + gaussian noise N(0, 1e-1).\n"
" The real and the measured points are connected with red line segment,\n"
" the real and the estimated points are connected with yellow line segment,\n"
" the real and the corrected estimated points are connected with green line segment.\n"
" (if Kalman filter works correctly,\n"
" the yellow segment should be shorter than the red one).\n"
" the yellow segment should be shorter than the red one and\n"
" the green segment should be shorter than the yellow one)."
"\n"
" Pressing any key (except ESC) will reset the tracking with a different speed.\n"
" Pressing any key (except ESC) will reset the tracking.\n"
" Pressing ESC will stop the program.\n"
);
}
@ -39,7 +43,9 @@ int main(int, char**)
for(;;)
{
randn( state, Scalar::all(0), Scalar::all(0.1) );
img = Scalar::all(0);
state.at<float>(0) = 0.0f;
state.at<float>(1) = 2.f * (float)CV_PI / 6;
KF.transitionMatrix = (Mat_<float>(2, 2) << 1, 1, 0, 1);
setIdentity(KF.measurementMatrix);
@ -60,36 +66,40 @@ int main(int, char**)
double predictAngle = prediction.at<float>(0);
Point predictPt = calcPoint(center, R, predictAngle);
randn( measurement, Scalar::all(0), Scalar::all(KF.measurementNoiseCov.at<float>(0)));
// generate measurement
randn( measurement, Scalar::all(0), Scalar::all(KF.measurementNoiseCov.at<float>(0)));
measurement += KF.measurementMatrix*state;
double measAngle = measurement.at<float>(0);
Point measPt = calcPoint(center, R, measAngle);
// correct the state estimates based on measurements
// updates statePost & errorCovPost
KF.correct(measurement);
double improvedAngle = KF.statePost.at<float>(0);
Point improvedPt = calcPoint(center, R, improvedAngle);
// plot points
#define drawCross( center, color, d ) \
line( img, Point( center.x - d, center.y - d ), \
Point( center.x + d, center.y + d ), color, 1, LINE_AA, 0); \
line( img, Point( center.x + d, center.y - d ), \
Point( center.x - d, center.y + d ), color, 1, LINE_AA, 0 )
img = img * 0.2;
drawMarker(img, measPt, Scalar(0, 0, 255), cv::MARKER_SQUARE, 5, 2);
drawMarker(img, predictPt, Scalar(0, 255, 255), cv::MARKER_SQUARE, 5, 2);
drawMarker(img, improvedPt, Scalar(0, 255, 0), cv::MARKER_SQUARE, 5, 2);
drawMarker(img, statePt, Scalar(255, 255, 255), cv::MARKER_STAR, 10, 1);
// forecast one step
Mat test = Mat(KF.transitionMatrix*KF.statePost);
drawMarker(img, calcPoint(center, R, Mat(KF.transitionMatrix*KF.statePost).at<float>(0)),
Scalar(255, 255, 0), cv::MARKER_SQUARE, 12, 1);
img = Scalar::all(0);
drawCross( statePt, Scalar(255,255,255), 3 );
drawCross( measPt, Scalar(0,0,255), 3 );
drawCross( predictPt, Scalar(0,255,0), 3 );
line( img, statePt, measPt, Scalar(0,0,255), 3, LINE_AA, 0 );
line( img, statePt, predictPt, Scalar(0,255,255), 3, LINE_AA, 0 );
line( img, statePt, measPt, Scalar(0,0,255), 1, LINE_AA, 0 );
line( img, statePt, predictPt, Scalar(0,255,255), 1, LINE_AA, 0 );
line( img, statePt, improvedPt, Scalar(0,255,0), 1, LINE_AA, 0 );
if(theRNG().uniform(0,4) != 0)
KF.correct(measurement);
randn( processNoise, Scalar(0), Scalar::all(sqrt(KF.processNoiseCov.at<float>(0, 0))));
state = KF.transitionMatrix*state + processNoise;
imshow( "Kalman", img );
code = (char)waitKey(100);
code = (char)waitKey(1000);
if( code > 0 )
break;

97
samples/python/kalman.py
View File

@ -1,14 +1,18 @@
#!/usr/bin/env python
"""
Tracking of rotating point.
Rotation speed is constant.
Point moves in a circle and is characterized by a 1D state.
state_k+1 = state_k + speed + process_noise N(0, 1e-5)
The speed is constant.
Both state and measurements vectors are 1D (a point angle),
Measurement is the real point angle + gaussian noise.
The real and the estimated points are connected with yellow line segment,
the real and the measured points are connected with red line segment.
Measurement is the real state + gaussian noise N(0, 1e-1).
The real and the measured points are connected with red line segment,
the real and the estimated points are connected with yellow line segment,
the real and the corrected estimated points are connected with green line segment.
(if Kalman filter works correctly,
the yellow segment should be shorter than the red one).
Pressing any key (except ESC) will reset the tracking with a different speed.
the yellow segment should be shorter than the red one and
the green segment should be shorter than the yellow one).
Pressing any key (except ESC) will reset the tracking.
Pressing ESC will stop the program.
"""
# Python 2/3 compatibility
@ -21,8 +25,7 @@ if PY3:
import numpy as np
import cv2 as cv
from math import cos, sin, sqrt
import numpy as np
from math import cos, sin, sqrt, pi
def main():
img_height = 500
@ -30,64 +33,62 @@ def main():
kalman = cv.KalmanFilter(2, 1, 0)
code = long(-1)
cv.namedWindow("Kalman")
num_circle_steps = 12
while True:
state = 0.1 * np.random.randn(2, 1)
kalman.transitionMatrix = np.array([[1., 1.], [0., 1.]])
kalman.measurementMatrix = 1. * np.ones((1, 2))
kalman.processNoiseCov = 1e-5 * np.eye(2)
kalman.measurementNoiseCov = 1e-1 * np.ones((1, 1))
kalman.errorCovPost = 1. * np.ones((2, 2))
kalman.statePost = 0.1 * np.random.randn(2, 1)
img = np.zeros((img_height, img_width, 3), np.uint8)
state = np.array([[0.0],[(2 * pi) / num_circle_steps]]) # start state
kalman.transitionMatrix = np.array([[1., 1.], [0., 1.]]) # F. input
kalman.measurementMatrix = 1. * np.eye(1, 2) # H. input
kalman.processNoiseCov = 1e-5 * np.eye(2) # Q. input
kalman.measurementNoiseCov = 1e-1 * np.ones((1, 1)) # R. input
kalman.errorCovPost = 1. * np.eye(2, 2) # P._k|k KF state var
kalman.statePost = 0.1 * np.random.randn(2, 1) # x^_k|k KF state var
while True:
def calc_point(angle):
return (np.around(img_width/2 + img_width/3*cos(angle), 0).astype(int),
np.around(img_height/2 - img_width/3*sin(angle), 1).astype(int))
return (np.around(img_width / 2. + img_width / 3.0 * cos(angle), 0).astype(int),
np.around(img_height / 2. - img_width / 3.0 * sin(angle), 1).astype(int))
img = img * 1e-3
state_angle = state[0, 0]
state_pt = calc_point(state_angle)
# advance Kalman filter to next timestep
# updates statePre, statePost, errorCovPre, errorCovPost
# k-> k+1, x'(k) = A*x(k)
# P'(k) = temp1*At + Q
prediction = kalman.predict()
predict_angle = prediction[0, 0]
predict_pt = calc_point(predict_angle)
measurement = kalman.measurementNoiseCov * np.random.randn(1, 1)
predict_pt = calc_point(prediction[0, 0]) # equivalent to calc_point(kalman.statePre[0,0])
# generate measurement
measurement = kalman.measurementNoiseCov * np.random.randn(1, 1)
measurement = np.dot(kalman.measurementMatrix, state) + measurement
measurement_angle = measurement[0, 0]
measurement_pt = calc_point(measurement_angle)
# plot points
def draw_cross(center, color, d):
cv.line(img,
(center[0] - d, center[1] - d), (center[0] + d, center[1] + d),
color, 1, cv.LINE_AA, 0)
cv.line(img,
(center[0] + d, center[1] - d), (center[0] - d, center[1] + d),
color, 1, cv.LINE_AA, 0)
img = np.zeros((img_height, img_width, 3), np.uint8)
draw_cross(np.int32(state_pt), (255, 255, 255), 3)
draw_cross(np.int32(measurement_pt), (0, 0, 255), 3)
draw_cross(np.int32(predict_pt), (0, 255, 0), 3)
cv.line(img, state_pt, measurement_pt, (0, 0, 255), 3, cv.LINE_AA, 0)
cv.line(img, state_pt, predict_pt, (0, 255, 255), 3, cv.LINE_AA, 0)
# correct the state estimates based on measurements
# updates statePost & errorCovPost
kalman.correct(measurement)
improved_pt = calc_point(kalman.statePost[0, 0])
process_noise = sqrt(kalman.processNoiseCov[0,0]) * np.random.randn(2, 1)
state = np.dot(kalman.transitionMatrix, state) + process_noise
# plot points
cv.drawMarker(img, measurement_pt, (0, 0, 255), cv.MARKER_SQUARE, 5, 2)
cv.drawMarker(img, predict_pt, (0, 255, 255), cv.MARKER_SQUARE, 5, 2)
cv.drawMarker(img, improved_pt, (0, 255, 0), cv.MARKER_SQUARE, 5, 2)
cv.drawMarker(img, state_pt, (255, 255, 255), cv.MARKER_STAR, 10, 1)
# forecast one step
cv.drawMarker(img, calc_point(np.dot(kalman.transitionMatrix, kalman.statePost)[0, 0]),
(255, 255, 0), cv.MARKER_SQUARE, 12, 1)
cv.line(img, state_pt, measurement_pt, (0, 0, 255), 1, cv.LINE_AA, 0) # red measurement error
cv.line(img, state_pt, predict_pt, (0, 255, 255), 1, cv.LINE_AA, 0) # yellow pre-meas error
cv.line(img, state_pt, improved_pt, (0, 255, 0), 1, cv.LINE_AA, 0) # green post-meas error
# update the real process
process_noise = sqrt(kalman.processNoiseCov[0, 0]) * np.random.randn(2, 1)
state = np.dot(kalman.transitionMatrix, state) + process_noise # x_k+1 = F x_k + w_k
cv.imshow("Kalman", img)
code = cv.waitKey(100)
code = cv.waitKey(1000)
if code != -1:
break