How to compute mean/std?

[DMCNerooo]

Hello, thanks for your interesting work! I wonder how to compute mean/std in the data folder, i.e. are they some statistics on training set? Looking forward to your reply!

[zhangboshen]

Sorry that I just see your comments yet.
And yes, we compute mean/std on training set, specifically, we first crop the original depth maps according to center points, which give us a hand-centered sub-image, then we compute the mean/std of all of these images.

[zhangboshen]

def findMean(center):
    trainingImageDir = './train_nyu/'
    mean_D = 0
    for i in tqdm(range(72757)):    #72757
        D_ = scio.loadmat(trainingImageDir + str(i+1) + '.mat')['depth']
        D_ = np.array(D_,dtype=np.float)
        new_Xmin = center[i][0][0] - cropHandWidth//2 
        new_Ymin = center[i][0][1] - cropHandHeight//2 
        new_Xmax = center[i][0][0] + cropHandWidth//2 
        new_Ymax = center[i][0][1] + cropHandHeight//2 

        D = D_[int(new_Ymin):int(new_Ymax), int(new_Xmin):int(new_Xmax)]
        D[np.where(D >= center[i][0][2] + 200)] = center[i][0][2]
        D[np.where(D <= center[i][0][2] - 200)] = center[i][0][2]
        D -= center[i][0][2]
                   
        
        mean_D_ = D.mean(0).mean(0)
        mean_D += mean_D_
#        print(i)
        
    mean_D /= 72757
    
    return mean_D

I hope this helps.

[DMCNerooo]

Yes it really helps and I have understood. Thanks for your kind explanation! I will close this issue

[canuck6ix]

Hello @zhangboshen, I tried to reproduce this but don't get the same results as yours. I believe it is the cropHandWidth and cropHandHeight. What values do you use for the above?

@DMCNerooo does yours match mean = -0.66877532 and std= 28.32958208

[DMCNerooo]

Hello @canuck6ix , I just want to understand the computation of mean/std in the data folder, but don't re-compute it. I use the value provided by the author. I think you can try to utilize above code "findMean" to get mean and then std, maybe there is little difference with author's but doesn't matter.
By the way, both cropHandWidth and cropHandHeight are set to 176 in this paper and project. Good luck!

[canuck6ix]

@DMCNerooo Thanks for confirming width and height. I did utilize the code above and they are a bit different from the pre-computed ones. Here are the two for comparison:
autor's: mean = -0.67 std = 28.33
mine: mean = -3.86 std = 21.13

[zhangboshen]

@DMCNerooo Thanks for confirming width and height. I did utilize the code above and they are a bit different from the pre-computed ones. Here are the two for comparison:
autor's: mean = -0.67 std = 28.33
mine: mean = -3.86 std = 21.13

@canuck6ix , I am sorry I just see your discuss now. And you can use your mean/std, I think you can also get a resonable result.