What is the problem addressed by the paper? How to represent smooth shapes? How to smooth surfaces? How to process rangescanned meshes? How to improv normal and boundary continuity? image credit Alexa, et al. What is the approach used to resolve the problem? In differential geometry, a smooth surface is characterized by the existence of smooth…
[Summary] The One Hundred Year Study on Artificial Intelligence: An Enduring Study on AI and its Influence on People and Society
Today, technical fellow and director at Microsoft, Dr. Horvitz gave a lecture on The One Hundred Year Study on Artificial Intelligence: An Enduring Study on AI and its Influence on People and Society; I am also fortunate to have a lunch together with Eric. He has presented an update on the One Hundred Year Study on AI, described…
FisherYates Shuffle
The correct way to do a shuffle is to choose a random other index to fill in the current index, which is uniform:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 
function getRandom(floor, ceiling) { return Math.floor(Math.random() * (ceiling  floor + 1)) + floor; } function shuffle(theArray) { // if it's 1 or 0 items, just return if (theArray.length <= 1) return; // walk through from beginning to end for (var indexWeAreChoosingFor = 0; indexWeAreChoosingFor < theArray.length; indexWeAreChoosingFor++) { // choose a random notyetplaced item to place there // (could also be the item currently in that spot) // must be an item AFTER the current item, because the stuff // before has all already been placed var randomChoiceIndex = getRandom(indexWeAreChoosingFor, theArray.length  1); // place our random choice in the spot by swapping var valueAtIndexWeChoseFor = theArray[indexWeAreChoosingFor]; theArray[indexWeAreChoosingFor] = theArray[randomChoiceIndex]; theArray[randomChoiceIndex] = valueAtIndexWeChoseFor; } } 
Also, you may need a uniform random generator in C++:
1 2 3 4 5 6 7 
#include <random> std::random_device rd; std::mt19937 mt(rd()); std::uniform_real_distribution<double> uniform_random(0.0, 1.0); // use as sample = uniform_random(mt); 
Protected: Optimization Using SumtoProduct Identities
There is no excerpt because this is a protected post.
Likert Scale and Paired TTest Are Not Good Friends
Nonparametric Tests Unfortunately, it’s the first time that I learnt that Likert scale cannot be used together with ttest. According to my favorite Stat Wiki by Prof. Koji Yatani, Roughly speaking, there are two cases in which you want to use nonparametric test: Ordinal data: If your data are ordinal (like the results from Likertscale…
What are PCA and FLA / LDA?
PCA The main idea of PCA is to seek the most accurate data representation in a lower dimensional space. For a formal definition, according to Wikipedia, Principal component analysis (PCA) is a statistical procedure that uses an orthogonal transformation to convert a set of observations of possibly correlated variables into a set of values of…
What is P value?
P value is the probability that you are wrong if you reject the null hypothesis. or P value is the probability that you get equal or worse result if your experiment is right… or according to Wikipedia: For example, if you propose a hypothesis that Trump has more positive tweets than Hillary has, the your…
N Queens Problem Revisit using Bit Operations
Finally, I have some time to revisit the N queens problem using bit operations. The following functions could solve 11 queens in 1 second:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 
class Solution { public: vector<vector<string>> solveNQueens(int n) { NQresult.clear(); NQpath.clear(); NQn = n; NQtotal = 0; bitNQueens(0, 0, 0); cout << NQtotal << endl; return NQresult; } private: /** [Q..... row = 101010 ..Q... ld = 100100 ....Q. rd = 000111 ......] or = 101111 pos = 010000 => p = (010000) & (110000) = 010000 => pos = 0; [Q..... row = 111010 ..Q... ld = 011000 ....Q. rd = 000111 .Q....] **/ vector<vector<string>> NQresult; vector<int> NQpath; int NQtotal; int NQn; void addNQueenSolution() { vector<string> v; for (int i = 0; i < NQn; ++i) v.push_back(string(NQn, '.')); for (int i = 0; i < NQn; ++i) { v[i][NQpath[i]] = 'Q'; //cout << v[i] << endl; } //cout << endl; NQresult.push_back(v); } // col: whether this col is occupied // ld: left diagnal for the current row // rd: right diagnal for the current row void bitNQueens(int col, int ld, int rd) { int allOccupied = (1 << NQn)  1; if (col == allOccupied) { ++NQtotal; addNQueenSolution(); return; } int pos = allOccupied & (~(col  ld  rd)); while (pos != 0) { int p = pos & (pos); // which way to go pos = pos  p; // get the rightmost 1 of position position NQpath.push_back(p == 1 ? 0 : (int)round(log(p) / log(2))); bitNQueens(col + p, (ld + p) << 1, (rd + p) >> 1); NQpath.pop_back(); } } }; 
So far to me, this is the most efficient algorithm for N queens. The code is mostly selfexplenary. Please comment if anything cannot be understood.
1 2 3 
// col: whether this col is occupied // ld: left diagnal for the current row // rd: right diagnal for the current row 
Simplest and Fatest GLSL Edge Detection using Fwidth
GLSL Edge Detection Yesterday, I read 834144373’s ShaderToy code which did GLSL Edge Detection in 97 chars, it was really simple and fast:
1 2 3 4 
void mainImage(out vec4 o, vec2 u) { o = o  length(fwidth(texture2D(iChannel0,u/iResolution.xy)))*3.; } 
Meanwhile, the rendering result is astonishingly awesome: However, there are some noise from the GLSL edge detection. Thus, I have made a little improvement on this algorithm and produced cleaner edges in this ShaderToy…
Testing GPUs Computational Power
Have you think of how many summation & multiply operations can you do within forloops in GPU fragment shader? I irrigorously tested the following fragment shader on ShaderToy, which gives me 100,000 operations at 22 FPS on a GTX 1080, for 25, 000 operations, it runs smoothly at 60 FPS. So, what’s the limitation of…
Clock
World
Random Posts
Share
Slideshow

Recent Posts
 [Talk Summary] HandSight: A TouchBased Wearable System to Increase Information Accessibility for People with Visual Impairments
 [Talk Summary] A largescale analysis of YouTube videos depicting everyday thermal camera use
 [Summary] Google I/O and Microsoft Build 2018
 [Summary] StackGAN: Text to Photorealistic Image Synthesis
 [Summary] Omnipresence 3D for Multiview Mixed Reality
Twitter
My TweetsRecent Comments
 Mr Zhu (@834144373zhu) on Tutorial of Ray Casting, Ray Tracing, Path Tracing and Ray Marching
 サンプリングレンダリングの解説記事 – Tech masuk on Tutorial of Ray Casting, Ray Tracing, Path Tracing and Ray Marching
 starea on Estimated Cost of Per Atom Function in Realtime Shaders on the GPU
 Ben Parry on Estimated Cost of Per Atom Function in Realtime Shaders on the GPU
 starea on My Chatbot in WeChat Platform
Archives
 August 2018
 May 2018
 April 2018
 March 2018
 November 2017
 October 2017
 August 2017
 July 2017
 April 2017
 March 2017
 February 2017
 January 2017
 December 2016
 November 2016
 October 2016
 September 2016
 June 2016
 April 2016
 March 2016
 February 2016
 December 2015
 November 2015
 October 2015
 September 2015
 August 2015
 July 2015
 June 2015
 May 2015
 September 2014
 September 2012
 October 2010
 May 2010
 July 2008
Categories
Meta