I try to implement the Halton sequence with this simple code:

def Halton(base,ix):
    r = 0
    f = 1.0 / base
    i = ix
    while(i > 0):
        r += f * (i%base)
        f /= base
        i /= base
    return r

i thought the output values are limited to [0..1] but sometimes i get values like "1.01953125" or "1.1861979166666667", why is that and how can i limit the Halton sequence to the given interval?

I try to implement the Halton sequence with this simple code:

def Halton(base,ix):
    r = 0
    f = 1.0 / base
    i = ix
    while(i > 0):
        r += f * (i%base)
        f /= base
        i /= base
    return r

i thought the output values are limited to [0..1] but sometimes i get values like "1.01953125" or "1.1861979166666667", why is that and how can i limit the Halton sequence to the given interval?

Try changing the line "i /= base" to something like "i = math.floor(i / base)". ( https://en.wikipedia.org/wiki/Halton_sequence if you look at the pseudocode, it has the floor operation too. )

Thanks the floor function fixed it. I am wondering how i could use the halton sequence to sample a pixel? Would it be better to store the precalculated values in an array and choose the value according to the current samples / pixel? For example if i am in the 2nd sample i would choose the 2nd value of the 2- and 3-base halton series?

I implemented a new class called "Sampler" which generates either random values, halton (2,3) values or sobol values and stores them before in an array before rendering. I tried every one and compared the results at 10 samples, and i am kind of disappointed by halton and sobol, they both look horrible, why is that?

This is my computeSamples(x,y)-function:

def computeSample(x,y):
    samplePoint = sampler.getSamplePoint(x,y)

    jitterX = samplePoint[0]
    jitterY = samplePoint[1]

    x += jitterX
    y += jitterY

    xdir = (x / width) * 2.0 - 1.0
    ydir = ((y / height) * 2.0 - 1.0) * aspect

    direction = Point3D(xdir,ydir,zdir).normalize()
    ray = Ray(camera,direction)

    return trace(ray,1)

And this is my "Sampler":

class Sampler:
    def __init__(self,type,width,height):
        self.type = type
        self.width = width
        self.height = height
        self.samplePoints = []
        self.counter = 0
        for x in range(width):
            for y in range(height):
                if(self.type is SampleType.Random):
                    self.samplePoints.append([random(),random()])
                elif(self.type is SampleType.Halton):
                    self.samplePoints.append([Halton(2,self.counter),Halton(3,self.counter)])
                elif(self.type is SampleType.Sobol):
                    sobolValue = i4_sobol(2,self.counter)
                    self.samplePoints.append([sobolValue[0][0],sobolValue[0][1]])
                elif(self.type is SampleType.NoneS):
                    self.samplePoints.append([0,0])
                self.counter += 1

    def getSamplePoint(self,x,y):
        return self.samplePoints[x*self.height+y]