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non_gps: added feature matching and offset calculation #62

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182 changes: 182 additions & 0 deletions Common/Ubuntu/ap_camera_non_gps/feature_match.py
Original file line number Diff line number Diff line change
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import numpy as np
import cv2 as cv
from matplotlib import pyplot as plt
import subprocess
import pyexiv2, json
import math

x_offset = 0
y_offset = 0

MIN_MATCH_COUNT = 30

LOCATION_SCALING_FACTOR_INV = 89.83204953368922

inCMX = 0
inCMY = 0

focal = 476.7030836014194



def readExif(image):
with open(image, 'rb') as f:
with pyexiv2.ImageData(f.read()) as img:
data = img.read_exif()
print(data['Exif.Photo.UserComment'])
f.close()

def modifyExif(image,data=None):
with open(image, 'rb+') as f:
with pyexiv2.ImageData(f.read()) as img:
matadata = data
dict1 = {'Exif.Photo.UserComment': json.dumps(metadata)}
img.modify_exif(dict1)

f.seek(0)
f.truncate()
f.write(img.get_bytes())
f.seek(0)
with pyexiv2.ImageData(f.read()) as img:
result = img.read_exif()
#print(result)
f.close()


def compParam(img1,img2):
global inCMY, inCMX
global x_offset, y_offset
img1 = cv.imread(img1,0)
img2 = cv.imread(img2,0)
#img2 = cv.resize(img2, (1778,866))
sift = cv.SIFT_create(nfeatures = 10000)

kp1, des1 = sift.detectAndCompute(img1,None)
kp2, des2 = sift.detectAndCompute(img2,None)
FLANN_INDEX_KDTREE = 1
index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 5)
search_params = dict(checks = 50)
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If you plan to run this to run at a regular rate, it might be wise to iteratively adjust the checks over time to optimize the computation time against the desired output rate. It might depend if you want to run this algorithm on every frame, or skip frames in order to get higher checks.

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Understood sir! You mean it could be better to do frequent checks on image frames rather than continuous checks on frames, I'll make it to check for features at frequent intervals

flann = cv.FlannBasedMatcher(index_params, search_params)
matches = flann.knnMatch(des1,des2,k=2)

good = []
for m,n in matches:
if m.distance < 0.7*n.distance:
good.append(m)


if len(good)>MIN_MATCH_COUNT:
src_pts = np.float32([ kp1[m.queryIdx].pt for m in good ]).reshape(-1,1,2)
dst_pts = np.float32([ kp2[m.trainIdx].pt for m in good ]).reshape(-1,1,2)
M, mask = cv.findHomography(src_pts, dst_pts, cv.RANSAC,5.0)
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For finding homography, since the images are in quick succession and not arbitrarily different transforms, are there any algorithms that may be optimized based on an initial guess?

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@Ryanf55 I am not sure if it is what you are mentioning, but Iterative Closest Point algorithm can serve the purpose. If it is required, I'll add it in the main algorithm

matchesMask = mask.ravel().tolist()
h,w = img1.shape
pts = np.float32([ [0,0],[0,h-1],[w-1,h-1],[w-1,0] ]).reshape(-1,1,2)
dst = cv.perspectiveTransform(pts,M)
img2 = cv.polylines(img2,[np.int32(dst)],True,255,3, cv.LINE_AA)



#Orientation

diff = np.abs(dst - pts)
orientation_diff = np.arctan2(np.abs(dst[1][0][1] - dst[0][0][1]), np.abs(dst[1][0][0] - dst[0][0][0]))
print("Orientation difference: {:.2f} degrees".format(90 - np.degrees(orientation_diff)))


#x, y offset

h1, w1 = img1.shape[:2]
h, w = img2.shape

sr_pts = np.float32([kp1[m.queryIdx].pt for m in good]).reshape(-1, 1, 2)
ds_pts = np.float32([kp2[m.trainIdx].pt for m in good]).reshape(-1, 1, 2)
Mr, maskr = cv.findHomography(ds_pts, sr_pts, cv.RANSAC, 5.0)

corners = np.array([[0, 0], [0, h-1], [w-1, h-1], [w-1, 0]], dtype=np.float32).reshape(-1, 1, 2)
transformed_corners = cv.perspectiveTransform(corners, Mr)

x, y = np.mean(transformed_corners, axis=0).astype(int)[0]

print("Offset x, y: ",x-w1/2, y-h1/2)

inCMX = (x-w1/2) * (10) / focal
inCMY = (y-h1/2) * (10) / focal


#Zoom percentage -- Not complete

width = abs(transformed_corners[2][0][0]) - abs(transformed_corners[0][0][0])
height = abs(transformed_corners[2][0][1]) - abs(transformed_corners[0][0][1])

im2 = width * height
im1 = img1.shape[0] * img1.shape[1]

#print(transformed_corners)

print(f"Zoom percent: {im2/im1*100} %")

else:
print( "Not enough matches are found - {}/{}".format(len(good), MIN_MATCH_COUNT) )
matchesMask = None


draw_params = dict(matchColor = (0,255,0),
singlePointColor = (255,0,0),
matchesMask = matchesMask,
flags = 2)


binToBool= [True if n == 1 else False for n in matchesMask]
res = list(filter(lambda i: binToBool[i], range(len(binToBool))))
res_listQ = [src_pts[i].tolist() for i in res]
res_listT = [dst_pts[i].tolist() for i in res]


cv.namedWindow("img3", cv.WINDOW_NORMAL)
img3 = cv.drawMatches(img1,kp1,img2,kp2,good,None,**draw_params)

cv.imshow('img3', img3)

cv.waitKey(0)



def offset_latlng(lat,lng,ofs_north,ofs_east):
dlat = ofs_north * LOCATION_SCALING_FACTOR_INV
dlng = (ofs_east * LOCATION_SCALING_FACTOR_INV) / longitude_scale(lat+dlat/2)
lat += dlat
lat = limit_lattitude(lat)
lng = wrap_longitude(dlng+lng)
print("New Lat & Lng: ",lat,lng)

def MAX(one, two):
return one if one > two else two
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def longitude_scale(lat):
scale = math.cos(lat * (1.0e-7 * (math.pi/180)))
return MAX(scale, 0.01)


def limit_lattitude(lat):
if lat > 900000000:
lat = 1800000000 - lat
elif lat < -900000000:
lat = -(1800000000 + lat)
return lat


def wrap_longitude(lon):
if lon > 1800000000:
lon = int(lon-3600000000)
elif lon < -1800000000:
lon = int(lon+3600000000)
return int(lon)


if __name__ == '__main__':

compParam("test1.png",'test2.png') #To find the features and get orientation, offset and zoom

offset_latlng(-353632621,1491652378,-inCMX,inCMY) #Extract new lat and lng based upon pixel offset

5 changes: 5 additions & 0 deletions Common/Ubuntu/ap_camera_non_gps/requirements.txt
Original file line number Diff line number Diff line change
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numpy==1.24.1
opencv-python==4.7.0.68
opencv-contrib-python==4.7.0.68
matplotlib==3.6.2
pyexiv2==2.8.1
Binary file added Common/Ubuntu/ap_camera_non_gps/test1.png
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Binary file added Common/Ubuntu/ap_camera_non_gps/test2.png
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