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Equirectangular panorama to cube map (Python 3)
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| import sys | |
| from PIL import Image | |
| from math import pi,sin,cos,tan,atan2,hypot,floor | |
| from numpy import clip | |
| # get x,y,z coords from out image pixels coords | |
| # i,j are pixel coords | |
| # face is face number | |
| # edge is edge length | |
| def outImgToXYZ(i,j,face,edge): | |
| a = 2.0*float(i)/edge | |
| b = 2.0*float(j)/edge | |
| if face==0: # back | |
| (x,y,z) = (-1.0, 1.0-a, 3.0 - b) | |
| elif face==1: # left | |
| (x,y,z) = (a-3.0, -1.0, 3.0 - b) | |
| elif face==2: # front | |
| (x,y,z) = (1.0, a - 5.0, 3.0 - b) | |
| elif face==3: # right | |
| (x,y,z) = (7.0-a, 1.0, 3.0 - b) | |
| elif face==4: # top | |
| (x,y,z) = (b-1.0, a -5.0, 1.0) | |
| elif face==5: # bottom | |
| (x,y,z) = (5.0-b, a-5.0, -1.0) | |
| return (x,y,z) | |
| # convert using an inverse transformation | |
| def convertBack(imgIn,imgOut): | |
| inSize = imgIn.size | |
| outSize = imgOut.size | |
| inPix = imgIn.load() | |
| outPix = imgOut.load() | |
| edge = inSize[0]/4 # the length of each edge in pixels | |
| for i in range(outSize[0]): | |
| face = int(i/edge) # 0 - back, 1 - left 2 - front, 3 - right | |
| if face==2: | |
| rng = range(0,int(edge*3)) | |
| else: | |
| rng = range(int(edge), int(edge) * 2) | |
| for j in rng: | |
| if j<edge: | |
| face2 = 4 # top | |
| elif j>=2*edge: | |
| face2 = 5 # bottom | |
| else: | |
| face2 = face | |
| (x,y,z) = outImgToXYZ(i,j,face2,edge) | |
| theta = atan2(y,x) # range -pi to pi | |
| r = hypot(x,y) | |
| phi = atan2(z,r) # range -pi/2 to pi/2 | |
| # source img coords | |
| uf = ( 2.0*edge*(theta + pi)/pi ) | |
| vf = ( 2.0*edge * (pi/2 - phi)/pi) | |
| # Use bilinear interpolation between the four surrounding pixels | |
| ui = floor(uf) # coord of pixel to bottom left | |
| vi = floor(vf) | |
| u2 = ui+1 # coords of pixel to top right | |
| v2 = vi+1 | |
| mu = uf-ui # fraction of way across pixel | |
| nu = vf-vi | |
| # Pixel values of four corners | |
| # import sys | |
| # print('inPix ->', inPix) | |
| # print('ui ->', ui) | |
| # print('inSize[0]', inSize[0]) | |
| # bar = clip(vi,0,inSize[1]-1) | |
| # print('bar ->', bar, type(bar), int(bar)) | |
| # baz = ui % inSize[0] | |
| # print('baz ->', baz, type(baz)) | |
| # foo = inPix[ui % inSize[0], bar] | |
| # sys.exit(-1) | |
| A = inPix[ui % inSize[0],int(clip(vi,0,inSize[1]-1))] | |
| B = inPix[u2 % inSize[0],int(clip(vi,0,inSize[1]-1))] | |
| C = inPix[ui % inSize[0],int(clip(v2,0,inSize[1]-1))] | |
| D = inPix[u2 % inSize[0],int(clip(v2,0,inSize[1]-1))] | |
| # interpolate | |
| (r,g,b) = ( | |
| A[0]*(1-mu)*(1-nu) + B[0]*(mu)*(1-nu) + C[0]*(1-mu)*nu+D[0]*mu*nu, | |
| A[1]*(1-mu)*(1-nu) + B[1]*(mu)*(1-nu) + C[1]*(1-mu)*nu+D[1]*mu*nu, | |
| A[2]*(1-mu)*(1-nu) + B[2]*(mu)*(1-nu) + C[2]*(1-mu)*nu+D[2]*mu*nu ) | |
| outPix[i,j] = (int(round(r)),int(round(g)),int(round(b))) | |
| imgIn = Image.open(sys.argv[1]) | |
| inSize = imgIn.size | |
| i1 = inSize[0] | |
| imgOut = Image.new("RGB",(inSize[0],int(inSize[0]*3/4)),"black") | |
| convertBack(imgIn,imgOut) | |
| imgOut.save(sys.argv[1].split('.')[0]+"Out2.png") | |
| imgOut.show() |
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