#?USAGE
#?python?object_size.py?--image?images/example_01.png?--width?0.955
#?python?object_size.py?--image?images/example_02.png?--width?0.955
#?python?object_size.py?--image?images/example_03.png?--width?3.5

#?import?the?necessary?packages
from?scipy.spatial?import?distance?as?dist
from?imutils?import?perspective
from?imutils?import?contours
import?numpy?as?np
import?argparse
import?imutils
import?cv2

def?midpoint（ptA?ptB）:
	return?（（ptA[0]?+?ptB[0]）?*?0.5?（ptA[1]?+?ptB[1]）?*?0.5）

#?construct?the?argument?parse?and?parse?the?arguments
ap?=?argparse.ArgumentParser（）
ap.add_argument（“-i“?“--image“?required=True
	help=“path?to?the?input?image“）
ap.add_argument（“-w“?“--width“?type=float?required=True
	help=“width?of?the?left-most?object?in?the?image?（in?inches）“）
args?=?vars（ap.parse_args（））

#?load?the?image?convert?it?to?grayscale?and?blur?it?slightly
image?=?cv2.imread（args[“image“]）
gray?=?cv2.cvtColor（image?cv2.COLOR_BGR2GRAY）
gray?=?cv2.GaussianBlur（gray?（7?7）?0）

#?perform?edge?detection?then?perform?a?dilation?+?erosion?to
#?close?gaps?in?between?object?edges
edged?=?cv2.Canny（gray?50?100）
edged?=?cv2.dilate（edged?None?iterations=1）
edged?=?cv2.erode（edged?None?iterations=1）

#?find?contours?in?the?edge?map
cnts?=?cv2.findContours（edged.copy（）?cv2.RETR_EXTERNAL
	cv2.CHAIN_APPROX_SIMPLE）
cnts?=?cnts[0]?if?imutils.is_cv2（）?else?cnts[1]

#?sort?the?contours?from?left-to-right?and?initialize?the
#?‘pixels?per?metric‘?calibration?variable
（cnts?_）?=?contours.sort_contours（cnts）
pixelsPerMetric?=?None

#?loop?over?the?contours?individually
for?c?in?cnts:
	#?if?the?contour?is?not?sufficiently?large?ignore?it
	if?cv2.contourArea（c）?		continue

	#?compute?the?rotated?bounding?box?of?the?contour
	orig?=?image.copy（）
	box?=?cv2.minAreaRect（c）
	box?=?cv2.cv.BoxPoints（box）?if?imutils.is_cv2（）?else?cv2.boxPoints（box）
	box?=?np.array（box?dtype=“int“）

	#?order?the?points?in?the?contour?such?that?they?appear
	#?in?top-left?top-right?bottom-right?and?bottom-left
	#?order?then?draw?the?outline?of?the?rotated?bounding
	#?box
	box?=?perspective.order_points（box）
	cv2.drawContours（orig?[box.astype（“int“）]?-1?（0?255?0）?2）

	#?loop?over?the?original?points?and?draw?them
	for?（x?y）?in?box:
		cv2.circle（orig?（int（x）?int（y））?5?（0?0?255）?-1）

	#?unpack?the?ordered?bounding?box?then?compute?the?midpoint
	#?between?the?top-left?and?top-right?coordinates?followed?by
	#?the?midpoint?between?bottom-left?and?bottom-right?coordinates
	（tl?tr?br?bl）?=?box
	（tltrX?tltrY）?=?midpoint（tl?tr）
	（blbrX?blbrY）?=?midpoint（bl?br）

	#?compute?the?midpoint?between?the?top-left?and?top-right?points
	#?followed?by?the?midpoint?between?the?top-righ?and?bottom-right
	（tlblX?tlblY）?=?midpoint（tl?bl）
	（trbrX?trbrY）?=?midpoint（tr?br）

	#?draw?the?midpoints?on?the?image
	cv2.circle（orig?（int（tltrX）?int（tltrY））?5?（255?0?0）?-1）
	cv2.circle（orig?（int（blbrX）?int（blbrY））?5?（255?0?0）?-1）
	cv2.circle（orig?（int（tlblX）?