Ask Your Question
0

Difficulties getting projectPoints to work, returns weird values [closed]

asked 2018-05-24 01:30:30 -0600

ekuusi gravatar image

updated 2018-05-24 01:56:35 -0600

berak gravatar image

I'm having trouble getting projectPoints to work. I've calibrated the camera and used solvPNP as in this tutorial:

https://longervision.github.io/2017/0...

The images obtained from the video I recorded showed that the blob detection worked fine, so this part I'm pretty confident works as intended.

Then I got registered some coordinates from an image to their real world corresponding points. I would expect projectPoints should return the same imagePoints coordinates if I would use projectPoints with some of the reference points as inputs, but instead I'm getting output values that are wildly outside the image coordinates.

I wonder what I'm doing wrong? Any help is greatly appreciated! After this I'm also trying to figure out how to do this in inverse: input imagePoints and get out objectPoints with z=0

My input points for projectPoints are:

inPoints = np.zeros((3, 3))
inPoints[0]  = (0 , 137.16  , 0)
inPoints[1]  = (0 , 548.64 , 0)
inPoints[2]  = (548.64 , 548.64, 0)

Expected Output:

(326, 156)
(398, 154)
(406, 170)

What I'm actually getting:

(19748.51884776, 14658.66747407)
 (24693.12654318,  9023.29722927)
 (33225.96561506,  3969.11639187)

Inputs:

rvec = [[-0.06161642] [ 0.74999101] [ 0.78220654]]
tvec = [[-914.24171214] [-834.30392656] [1188.29684866]]
cameraMatrix = [[2.25545289e+03 0.00000000e+00 1.27534861e+03]
                [0.00000000e+00 2.32542640e+03 7.35878530e+02]
                [0.00000000e+00 0.00000000e+00 1.00000000e+00]]
distCoeffs = [[-3.18000851e-02  1.83258452e+00 -4.43437310e-03  5.27295127e-03 -1.12934335e+01]]

Full script (after calibration):

import numpy as np
import cv2
import glob
import sys
import yaml

with open('./calib/calibration.yaml') as f:
    loadeddict = yaml.load(f)
camera_matrix = loadeddict.get('camera_matrix')
dist_coeffs = loadeddict.get('dist_coeff')


tnsPoints = np.zeros((19, 3)) 
tnsPoints[0]  = (0 , 0  , 0)
tnsPoints[1]  = (0 , 137.16 , 0)
tnsPoints[2]  = (0 , 548.64, 0)
tnsPoints[3]  = (0 , 960.12, 0)
tnsPoints[4]  = (0 , 1097.28 , 0)
tnsPoints[5]  = (548.64, 137.16, 0)
tnsPoints[6]  = (548.64, 548.64, 0)
tnsPoints[7]  = (548.64, 960.12, 0)
tnsPoints[8]  = (1188.72 , 0, 0)
tnsPoints[9]  = (1188.72 , 137.16, 0)
tnsPoints[10]  = (1188.72 , 548.64, 0)
tnsPoints[11]  = (1188.72 , 960.12, 0)
tnsPoints[12]  = (1188.72 , 1097.28, 0)
tnsPoints[13]  = (1828.80 , 137.16, 0)
tnsPoints[14]  = (1828.80 , 548.64, 0)
tnsPoints[15]  = (1828.80 , 960.12, 0)
tnsPoints[16]  = (2377.44 , 0  , 0)
tnsPoints[17]  = (2377.44 , 137.16  , 0)
tnsPoints[18]  = (2377.44 , 548.64  , 0)
#tnsPoints[19]  = (2377.44 , 960.12  , 0)
#tnsPoints[20]  = (2377.44 , 1097.28  , 0)

imPoints = np.zeros((19,2))
imPoints[0] = (302,158)
imPoints[1] = (326, 156)
imPoints[2] = (398, 154)
imPoints[3] = (471, 150)
imPoints[4] = (494, 148)
imPoints[5] = (319, 172)
imPoints[6] = (406, 170)
imPoints[7] = (491, 167)
imPoints[8] = (270, 206)
imPoints[9] = (306, 206)
imPoints[10] = (421, 203)
imPoints[11] = (532, 197)
imPoints[12] = (570, 195)
imPoints[13] = (283, 266)
imPoints[14] = (446, 260)
imPoints[15] = (607, 252)
imPoints[16 ...
(more)
edit retag flag offensive reopen merge delete

Closed for the following reason the question is answered, right answer was accepted by ekuusi
close date 2018-05-28 02:32:27.608498

1 answer

Sort by ยป oldest newest most voted
1

answered 2018-05-28 02:32:18 -0600

ekuusi gravatar image

Turns out the calibration was out of whack, need to check the calibration code again as the camera matrix values weren't right.

Closing this.

edit flag offensive delete link more

Question Tools

1 follower

Stats

Asked: 2018-05-24 01:30:30 -0600

Seen: 551 times

Last updated: May 28 '18