计算机视觉——增强现实(Augmented Reality)
文章目录
一、增强现实原理及介绍
1、增强现实介绍
增强现实,是将物体和相应信息放置在图像数据上的一系列操作的总称。事实上,增强现实在我们生活中的应用已经相当广泛了。比如任天堂的pokeman go,这个产品可以使你看到皮卡丘,杰尼龟出现在现实世界的场景里, 并捕捉他们,这个应该是无数90后小时候的梦想,AR使它变成了现实。
2、增强现实原理介绍
对于背景场景,我们需要首先给定标记,通过计算,获得自己计算机的标定信息,使用获取信息,放置目标模型的图像,获得我们需要的增强现实结果。
二、增强现实应用
1、应用背景介绍
应用目的是将一个茶杯图像放置到一段视频里,下面我们将进行计算机标定,以及目标合成。
2、AR应用
2.1、相机矩阵标定
下面这张是用来进行相机矩阵标定的图片
首先,相机到目标物体的距离d为500mm,计算出书的边长fX,fY。以及相片里书的边长fx,fy
利用
Px=fx/fX∗d
fy=fy/fY∗d
计算出相机的焦距。
2.2、作为目标背景的图片
2.3、代码部分
import math
import pickle
from pylab import *
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
import pygame, pygame.image
from pygame.locals import *
from PCV.geometry import homography, camera
from PCV.localdescriptors import sift
def cube_points(c, wid):
""" Creates a list of points for plotting
a cube with plot. (the first 5 points are
the bottom square, some sides repeated). """
p = []
# bottom
p.append([c[0]-wid, c[1]-wid, c[2]-wid])
p.append([c[0]-wid, c[1]+wid, c[2]-wid])
p.append([c[0]+wid, c[1]+wid, c[2]-wid])
p.append([c[0]+wid, c[1]-wid, c[2]-wid])
p.append([c[0]-wid, c[1]-wid, c[2]-wid]) #same as first to close plot
# top
p.append([c[0]-wid, c[1]-wid, c[2]+wid])
p.append([c[0]-wid, c[1]+wid, c[2]+wid])
p.append([c[0]+wid, c[1]+wid, c[2]+wid])
p.append([c[0]+wid, c[1]-wid, c[2]+wid])
p.append([c[0]-wid, c[1]-wid, c[2]+wid]) #same as first to close plot
# vertical sides
p.append([c[0]-wid, c[1]-wid, c[2]+wid])
p.append([c[0]-wid, c[1]+wid, c[2]+wid])
p.append([c[0]-wid, c[1]+wid, c[2]-wid])
p.append([c[0]+wid, c[1]+wid, c[2]-wid])
p.append([c[0]+wid, c[1]+wid, c[2]+wid])
p.append([c[0]+wid, c[1]-wid, c[2]+wid])
p.append([c[0]+wid, c[1]-wid, c[2]-wid])
return array(p).T
def my_calibration(sz):
row, col = sz
fx = 2245*col/3120
fy = 2173*row/4160
K = diag([fx, fy, 1])
K[0, 2] = 0.5*col
K[1, 2] = 0.5*row
return K
def set_projection_from_camera(K):
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
fx = K[0,0]
fy = K[1,1]
fovy = 2*math.atan(0.5*height/fy)*180/math.pi
aspect = (width*fy)/(height*fx)
near = 0.1
far = 100.0
gluPerspective(fovy,aspect,near,far)
glViewport(0,0,width,height)
def set_modelview_from_camera(Rt):
glMatrixMode(GL_MODELVIEW)
glLoadIdentity()
Rx = np.array([[1,0,0],[0,0,-1],[0,1,0]])
R = Rt[:,:3]
U,S,V = np.linalg.svd(R)
R = np.dot(U,V)
R[0,:] = -R[0,:]
t = Rt[:,3]
M = np.eye(4)
M[:3,:3] = np.dot(R,Rx)
M[:3,3] = t
M = M.T
m = M.flatten()
glLoadMatrixf(m)
def draw_background(imname):
bg_image = pygame.image.load(imname).convert()
bg_data = pygame.image.tostring(bg_image,"RGBX",1)
glMatrixMode(GL_MODELVIEW)
glLoadIdentity()
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glEnable(GL_TEXTURE_2D)
glBindTexture(GL_TEXTURE_2D,glGenTextures(1))
glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,width,height,0,GL_RGBA,GL_UNSIGNED_BYTE,bg_data)
glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST)
glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST)
glBegin(GL_QUADS)
glTexCoord2f(0.0,0.0); glVertex3f(-1.0,-1.0,-1.0)
glTexCoord2f(1.0,0.0); glVertex3f( 1.0,-1.0,-1.0)
glTexCoord2f(1.0,1.0); glVertex3f( 1.0, 1.0,-1.0)
glTexCoord2f(0.0,1.0); glVertex3f(-1.0, 1.0,-1.0)
glEnd()
glDeleteTextures(1)
def draw_teapot(size):
glEnable(GL_LIGHTING)
glEnable(GL_LIGHT0)
glEnable(GL_DEPTH_TEST)
glClear(GL_DEPTH_BUFFER_BIT)
glMaterialfv(GL_FRONT,GL_AMBIENT,[0,0,0,0])
glMaterialfv(GL_FRONT,GL_DIFFUSE,[0.5,0.0,0.0,0.0])
glMaterialfv(GL_FRONT,GL_SPECULAR,[0.7,0.6,0.6,0.0])
glMaterialf(GL_FRONT,GL_SHININESS,0.25*128.0)
glutSolidTeapot(size)
width,height = 1000,747
def setup():
pygame.init()
pygame.display.set_mode((width,height),OPENGL | DOUBLEBUF)
pygame.display.set_caption("OpenGL AR demo")
# compute features
sift.process_image('book_frontal.JPG', 'im0.sift')
l0, d0 = sift.read_features_from_file('im0.sift')
sift.process_image('book_perspective.JPG', 'im1.sift')
l1, d1 = sift.read_features_from_file('im1.sift')
# match features and estimate homography
matches = sift.match_twosided(d0, d1)
ndx = matches.nonzero()[0]
fp = homography.make_homog(l0[ndx, :2].T)
ndx2 = [int(matches[i]) for i in ndx]
tp = homography.make_homog(l1[ndx2, :2].T)
model = homography.RansacModel()
H, inliers = homography.H_from_ransac(fp, tp, model)
K = my_calibration((747, 1000))
cam1 = camera.Camera(hstack((K, dot(K, array([[0], [0], [-1]])))))
box = cube_points([0, 0, 0.1], 0.1)
box_cam1 = cam1.project(homography.make_homog(box[:, :5]))
box_trans = homography.normalize(dot(H,box_cam1))
cam2 = camera.Camera(dot(H, cam1.P))
A = dot(linalg.inv(K), cam2.P[:, :3])
A = array([A[:, 0], A[:, 1], cross(A[:, 0], A[:, 1])]).T
cam2.P[:, :3] = dot(K, A)
Rt=dot(linalg.inv(K),cam2.P)
setup()
draw_background("book_perspective.bmp")
set_projection_from_camera(K)
set_modelview_from_camera(Rt)
draw_teapot(0.05)
pygame.display.flip()
while True:
for event in pygame.event.get():
if event.type==pygame.QUIT:
sys.exit()