Moires patterns despite using mipmaps

Question

I am working on Silverlight app. I am trying to render floor covered with tiles. Although I am using mip maps I am still getting awful Moire patterns, when trying to render big area.

What I am doing is creating cuboid and then cover it with single tile:

In my pixel shader I am multiplying texture coordinates in order to create tiled floor (otherwise I would get one tile stretched over my cuboid). Pixel shader code:

float Width                 : register(c3);                  //Width of cuboid
float Height                : register(c4);                  //Height of cuboid

texture texTexture;
sampler textureSampler  : register(s0) = sampler_state {
    Texture = (texTexture);
};

struct VsOutput
{
    float4 position : POSITION;
    float3 dirLightPosition : COLOR;
    float2 texCoord : TEXCOORD0;
    float3 normal   : TEXCOORD1;
    float3 view : TEXCOORD2;
};

float4 main(VsOutput IN) : COLOR
{
    float2 texCoord = float2(IN.texCoord.x * Width / 4.0f, 
                             IN.texCoord.y * Height / 4.0f); //multiplying texture coordinates


    float4 texColor = tex2D(textureSampler, texCoord);

    return float4(color.r, color.g, color.b, 1.0f);
}

My output is:

What else can I do to prevent from creating Moires patterns on texture?

Answer 1

Two things come to mind:

1. When generating your smaller mip map levels try to avoid using a simple 2x2 box filter because, though cheap and cheerful, they do a really poor job of removing high frequency information (that exceeds the Nyquist limit) as well as over filtering some of the lower frequency information you need to keep. (Also, as an aside, you need to perform the MIP map generation in linear space. If your source data is sRGB, you thus need to map to and from linear). FWIW, In Williams' original paper on MIP mapping, he said he used a "box (Fourier) window" to generate the prefiltered levels, which would be a sinc function in image space.

2. Standard Trilinear filtering will also over- and under-filter parts of the texture. If you don't like the aliasing you may have to a) adjust the bias to increase the filtering (which will increase blurring) and/or b) try using anisotropic filtering.

Answer 2

SOLUTION

I managed to solve my problem by increacing size of texture 2048x2048px so there would be generated more mipmaps. Also it seems like changing my SamplerState form anisotropic to something like that helped:

SamplerState MirrorTexCoord = new SamplerState()
        {
            AddressU = TextureAddressMode.Mirror,
            AddressV = TextureAddressMode.Mirror,
            .
            .
            .
        };

Actually I don' t know what is TextureAdressMode.Mirror, but it helped a lot, now it looks like this: