With SSAO, even when drawing nothing, I get 50 fps. I think this is because of depth buffer overdraw.

The author in the book sets depth state to equal to prevent overdraw:

void Direct3D::DrawScene()
{
 
m_Smap->BindDsvAndSetNullRenderTarget(pDeviceContext);
 
DrawInstancedModelsToShadowMap();
 
DrawModelsToShadowMap();
 
//m_Land.DrawShadowMap(m_Cam);
 
pDeviceContext->RSSetState(0);
 
pDeviceContext->ClearDepthStencilView(m_DepthStencilView, D3D11_CLEAR_DEPTH|D3D11_CLEAR_STENCIL, 1.0f, 0);
pDeviceContext->RSSetViewports(1, &m_ViewPort);
m_Ssao->SetNormalDepthRenderTarget(m_DepthStencilView);
 
DrawModelsToSsaoMap();
 
//
// Now compute the ambient occlusion.
//
 
m_Ssao->ComputeSsao(m_Cam);
m_Ssao->BlurAmbientMap(4);
 
RestoreRenderTarget();
 
pDeviceContext->ClearRenderTargetView(m_RenderTargetView, reinterpret_cast<const float*>(&Colors::Silver));
//pDeviceContext->ClearDepthStencilView(m_DepthStencilView, D3D11_CLEAR_DEPTH|D3D11_CLEAR_STENCIL, 1.0f, 0);
 
 
m_Land.Draw(pDeviceContext, m_Cam, mDirLights);
 
// We already laid down scene depth to the depth buffer in the Normal/Depth map pass,
// so we can set the depth comparison test to “EQUALS.”  This prevents any overdraw
// in this rendering pass, as only the nearest visible pixels will pass this depth
// comparison test.
 
pDeviceContext->OMSetDepthStencilState(RenderStates::EqualsDSS, 0);
 
if (GetAsyncKeyState('1'))
pDeviceContext->RSSetState(RenderStates::WireframeRS);
 
DrawInstancedModels();
 
DrawModels();
//....
}

But with this

void Direct3D::DrawScene()
{
 
m_Smap->BindDsvAndSetNullRenderTarget(pDeviceContext);
 
DrawInstancedModelsToShadowMap();
 
DrawModelsToShadowMap();
 
//m_Land.DrawShadowMap(m_Cam);
 
pDeviceContext->RSSetState(0);
 
pDeviceContext->ClearDepthStencilView(m_DepthStencilView, D3D11_CLEAR_DEPTH|D3D11_CLEAR_STENCIL, 1.0f, 0);
pDeviceContext->RSSetViewports(1, &m_ViewPort);
m_Ssao->SetNormalDepthRenderTarget(m_DepthStencilView);
 
DrawModelsToSsaoMap();
 
//
// Now compute the ambient occlusion.
//
 
m_Ssao->ComputeSsao(m_Cam);
m_Ssao->BlurAmbientMap(4);
 
RestoreRenderTarget();
 
pDeviceContext->ClearRenderTargetView(m_RenderTargetView, reinterpret_cast<const float*>(&Colors::Silver));
//pDeviceContext->ClearDepthStencilView(m_DepthStencilView, D3D11_CLEAR_DEPTH|D3D11_CLEAR_STENCIL, 1.0f, 0);
 
 
m_Land.Draw(pDeviceContext, m_Cam, mDirLights);
 
// We already laid down scene depth to the depth buffer in the Normal/Depth map pass,
// so we can set the depth comparison test to “EQUALS.”  This prevents any overdraw
// in this rendering pass, as only the nearest visible pixels will pass this depth
// comparison test.
 
//pDeviceContext->OMSetDepthStencilState(RenderStates::EqualsDSS, 0);
 
if (GetAsyncKeyState('1'))
pDeviceContext->RSSetState(RenderStates::WireframeRS);
 
DrawInstancedModels();
 
DrawModels(); //..........

It works well.

Only the problem is performance.

Also what output debug messages say:

D3D11: ERROR: ID3D11DeviceContext::OMSetRenderTargets: The RenderTargetView at slot 0 is not compatable with the DepthStencilView. DepthStencilViews may only be used with RenderTargetViews if the effective dimensions of the Views are equal, as well as the Resource types, multisample count, and multisample quality. The RenderTargetView at slot 0 has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:1,mq:0). The DepthStencilView has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:4,mq:0). D3D11_RESOURCE_MISC_TEXTURECUBE factors into the Resource type, unless GetFeatureLevel() returns D3D_FEATURE_LEVEL_10_1 or greater. [ STATE_SETTING ERROR #388: OMSETRENDERTARGETS_INVALIDVIEW ]
D3D11: ERROR: ID3D11DeviceContext::OMSetRenderTargets: The RenderTargetView at slot 0 is not compatable with the DepthStencilView. DepthStencilViews may only be used with RenderTargetViews if the effective dimensions of the Views are equal, as well as the Resource types, multisample count, and multisample quality. The RenderTargetView at slot 0 has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:1,mq:0). The DepthStencilView has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:4,mq:0). D3D11_RESOURCE_MISC_TEXTURECUBE factors into the Resource type, unless GetFeatureLevel() returns D3D_FEATURE_LEVEL_10_1 or greater. [ STATE_SETTING ERROR #388: OMSETRENDERTARGETS_INVALIDVIEW ]
D3D11: ERROR: ID3D11DeviceContext::OMSetRenderTargets: The RenderTargetView at slot 0 is not compatable with the DepthStencilView. DepthStencilViews may only be used with RenderTargetViews if the effective dimensions of the Views are equal, as well as the Resource types, multisample count, and multisample quality. The RenderTargetView at slot 0 has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:1,mq:0). The DepthStencilView has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:4,mq:0). D3D11_RESOURCE_MISC_TEXTURECUBE factors into the Resource type, unless GetFeatureLevel() returns D3D_FEATURE_LEVEL_10_1 or greater. [ STATE_SETTING ERROR #388: OMSETRENDERTARGETS_INVALIDVIEW ]
D3D11: ERROR: ID3D11DeviceContext::OMSetRenderTargets: The RenderTargetView at slot 0 is not compatable with the DepthStencilView. DepthStencilViews may only be used with RenderTargetViews if the effective dimensions of the Views are equal, as well as the Resource types, multisample count, and multisample quality. The RenderTargetView at slot 0 has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:1,mq:0). The DepthStencilView has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:4,mq:0). D3D11_RESOURCE_MISC_TEXTURECUBE factors into the Resource type, unless GetFeatureLevel() returns D3D_FEATURE_LEVEL_10_1 or greater. [ STATE_SETTING ERROR #388: OMSETRENDERTARGETS_INVALIDVIEW ]
D3D11: ERROR: ID3D11DeviceContext::OMSetRenderTargets: The RenderTargetView at slot 0 is not compatable with the DepthStencilView. DepthStencilViews may only be used with RenderTargetViews if the effective dimensions of the Views are equal, as well as the Resource types, multisample count, and multisample quality. The RenderTargetView at slot 0 has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:1,mq:0). The DepthStencilView has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:4,mq:0). D3D11_RESOURCE_MISC_TEXTURECUBE factors into the Resource type, unless GetFeatureLevel() returns D3D_FEATURE_LEVEL_10_1 or greater. [ STATE_SETTING ERROR #388: OMSETRENDERTARGETS_INVALIDVIEW ]
D3D11: ERROR: ID3D11DeviceContext::OMSetRenderTargets: The RenderTargetView at slot 0 is not compatable with the DepthStencilView. DepthStencilViews may only be used with RenderTargetViews if the effective dimensions of the Views are equal, as well as the Resource types, multisample count, and multisample quality. The RenderTargetView at slot 0 has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:1,mq:0). The DepthStencilView has (w:492,h:473,as:1), while the Resource is a Texture2D with (mc:4,mq:0). D3D11_RESOURCE_MISC_TEXTURECUBE factors into the Resource type, unless GetFeatureLevel() returns D3D_FEATURE_LEVEL_10_1 or greater. [ STATE_SETTING ERROR #388: OMSETRENDERTARGETS_INVALIDVIEW ]

EDIT : When I viewed texture for debugging, it was empty i.e models are not getting drawn to SSAO map.

EDIT : When I viewed texture for debugging, it was empty i.e models are not getting drawn to SSAO map.

Just as the debug output messages say, I can barely rephrase it: The render target view is not compatible with the depth stencil view. In detail, your render target texture does not match the depth stencil buffer. They have to equal in size, multisamplecount, etc... otherwise nothing gets rendered.

EDIT: Also, concerning performance, we need to see your SSAO-shader.

Thanks, I changed my multi-sample quality to match depth buffer of render target view 0 and it worked.

There is now another problem.
Why is this happening?

EDIT: Also here is the SSAO shader

//=============================================================================
// Ssao.fx by Frank Luna (C) 2011 All Rights Reserved.
//
// Computes SSAO map.
//=============================================================================
 
cbuffer cbPerFrame
{
float4x4 gViewToTexSpace; // Proj*Texture
float4   gOffsetVectors[14];
float4   gFrustumCorners[4];
 
// Coordinates given in view space.
float    gOcclusionRadius    = 0.5f;
float    gOcclusionFadeStart = 0.2f;
float    gOcclusionFadeEnd   = 2.0f;
float    gSurfaceEpsilon     = 0.05f;
};
 
// Nonnumeric values cannot be added to a cbuffer.
Texture2D gNormalDepthMap;
Texture2D gRandomVecMap;
 
SamplerState samNormalDepth
{
Filter = MIN_MAG_LINEAR_MIP_POINT;
 
// Set a very far depth value if sampling outside of the NormalDepth map
// so we do not get false occlusions.
AddressU = BORDER;
AddressV = BORDER;
BorderColor = float4(0.0f, 0.0f, 0.0f, 1e5f);
};
 
SamplerState samRandomVec
{
Filter = MIN_MAG_LINEAR_MIP_POINT;
AddressU  = WRAP;
    AddressV  = WRAP;
};
 
struct VertexIn
{
float3 PosL            : POSITION;
float3 ToFarPlaneIndex : NORMAL;
float2 Tex             : TEXCOORD;
};
 
struct VertexOut
{
    float4 PosH       : SV_POSITION;
    float3 ToFarPlane : TEXCOORD0;
float2 Tex        : TEXCOORD1;
};
 
VertexOut VS(VertexIn vin)
{
VertexOut vout;
 
// Already in NDC space.
vout.PosH = float4(vin.PosL, 1.0f);
 
// We store the index to the frustum corner in the normal x-coord slot.
vout.ToFarPlane = gFrustumCorners[vin.ToFarPlaneIndex.x].xyz;
 
// Pass onto pixel shader.
vout.Tex = vin.Tex;
 
    return vout;
}
 
// Determines how much the sample point q occludes the point p as a function
// of distZ.
float OcclusionFunction(float distZ)
{
//
// If depth(q) is "behind" depth(p), then q cannot occlude p.  Moreover, if 
// depth(q) and depth(p) are sufficiently close, then we also assume q cannot
// occlude p because q needs to be in front of p by Epsilon to occlude p.
//
// We use the following function to determine the occlusion.  
// 
//
//       1.0     -------------\
//               |           |  \
//               |           |    \
//               |           |      \ 
//               |           |        \
//               |           |          \
//               |           |            \
//  ------|------|-----------|-------------|---------|--> zv
//        0     Eps          z0            z1        
//
 
float occlusion = 0.0f;
if(distZ > gSurfaceEpsilon)
{
float fadeLength = gOcclusionFadeEnd - gOcclusionFadeStart;
 
// Linearly decrease occlusion from 1 to 0 as distZ goes 
// from gOcclusionFadeStart to gOcclusionFadeEnd. 
occlusion = saturate( (gOcclusionFadeEnd-distZ)/fadeLength );
}
 
return occlusion; 
}
 
float4 PS(VertexOut pin, uniform int gSampleCount) : SV_Target
{
// p -- the point we are computing the ambient occlusion for.
// n -- normal vector at p.
// q -- a random offset from p.
// r -- a potential occluder that might occlude p.
 
// Get viewspace normal and z-coord of this pixel.  The tex-coords for
// the fullscreen quad we drew are already in uv-space.
float4 normalDepth = gNormalDepthMap.SampleLevel(samNormalDepth, pin.Tex, 0.0f);
 
float3 n = normalDepth.xyz;
float pz = normalDepth.w;
 
//
// Reconstruct full view space position (x,y,z).
// Find t such that p = t*pin.ToFarPlane.
// p.z = t*pin.ToFarPlane.z
// t = p.z / pin.ToFarPlane.z
//
float3 p = (pz/pin.ToFarPlane.z)*pin.ToFarPlane;
 
// Extract random vector and map from [0,1] --> [-1, +1].
float3 randVec = 2.0f*gRandomVecMap.SampleLevel(samRandomVec, 4.0f*pin.Tex, 0.0f).rgb - 1.0f;
 
float occlusionSum = 0.0f;
 
// Sample neighboring points about p in the hemisphere oriented by n.
[unroll]
for(int i = 0; i < gSampleCount; ++i)
{
// Are offset vectors are fixed and uniformly distributed (so that our offset vectors
// do not clump in the same direction).  If we reflect them about a random vector
// then we get a random uniform distribution of offset vectors.
float3 offset = reflect(gOffsetVectors[i].xyz, randVec);
 
// Flip offset vector if it is behind the plane defined by (p, n).
float flip = sign( dot(offset, n) );
 
// Sample a point near p within the occlusion radius.
float3 q = p + flip * gOcclusionRadius * offset;
 
// Project q and generate projective tex-coords.  
float4 projQ = mul(float4(q, 1.0f), gViewToTexSpace);
projQ /= projQ.w;
 
// Find the nearest depth value along the ray from the eye to q (this is not
// the depth of q, as q is just an arbitrary point near p and might
// occupy empty space).  To find the nearest depth we look it up in the depthmap.
 
float rz = gNormalDepthMap.SampleLevel(samNormalDepth, projQ.xy, 0.0f).a;
 
// Reconstruct full view space position r = (rx,ry,rz).  We know r
// lies on the ray of q, so there exists a t such that r = t*q.
// r.z = t*q.z ==> t = r.z / q.z
 
float3 r = (rz / q.z) * q;
 
//
// Test whether r occludes p.
//   * The product dot(n, normalize(r - p)) measures how much in front
//     of the plane(p,n) the occluder point r is.  The more in front it is, the
//     more occlusion weight we give it.  This also prevents self shadowing where 
//     a point r on an angled plane (p,n) could give a false occlusion since they
//     have different depth values with respect to the eye.
//   * The weight of the occlusion is scaled based on how far the occluder is from
//     the point we are computing the occlusion of.  If the occluder r is far away
//     from p, then it does not occlude it.
// 
 
float distZ = p.z - r.z;
float dp = max(dot(n, normalize(r - p)), 0.0f);
float occlusion = dp * OcclusionFunction(distZ);
 
occlusionSum += occlusion;
}
 
occlusionSum /= gSampleCount;
 
float access = 1.0f - occlusionSum;
 
// Sharpen the contrast of the SSAO map to make the SSAO affect more dramatic.
return saturate(pow(access, 4.0f));
}
 
technique11 Ssao
{
    pass P0
    {
SetVertexShader( CompileShader( vs_4_0, VS() ) );
SetGeometryShader( NULL );
        SetPixelShader( CompileShader( ps_4_0, PS(14) ) );
    }
}

Here is how i draw:

void Model::RenderNormalDepthMap(CXMMATRIX World, CXMMATRIX ViewProj)
{
ID3DX11EffectTechnique* activeTech = Effects::SsaoNormalDepthFX->NormalDepthTech;;
 
pDeviceContext->IASetInputLayout(InputLayouts::Basic32);
pDeviceContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST); 
 
XMMATRIX view = d3d->m_Cam.View();
 
XMMATRIX world = World;
XMMATRIX worldInvTranspose = MathHelper::InverseTranspose(world);
XMMATRIX worldView   = world* view;
XMMATRIX worldInvTransposeView = worldInvTranspose*view;
XMMATRIX worldViewProj = world * ViewProj;
 
 
D3DX11_TECHNIQUE_DESC techDesc;
    activeTech->GetDesc(&techDesc);
 
float blendFactor[4] = {0.0f, 0.0f, 0.0f, 0.0f};
 
    for(UINT p = 0; p < techDesc.Passes; ++p)
    {
for (UINT i = 0; i < mModel.mSubsetCount; i++)
   {    
Effects::SsaoNormalDepthFX->SetWorldView(worldView);
       Effects::SsaoNormalDepthFX->SetWorldInvTransposeView(worldInvTransposeView);
       Effects::SsaoNormalDepthFX->SetWorldViewProj(worldViewProj);
       Effects::SsaoNormalDepthFX->SetTexTransform(XMMatrixIdentity());
 
   activeTech->GetPassByIndex(p)->Apply(0, pDeviceContext);
 
   mModel.Mesh.Draw(i);
 
   }
}
}
 
void Model::Render(CXMMATRIX World, CXMMATRIX ViewProj)
{
ID3DX11EffectTechnique* activeTech;
 
pDeviceContext->IASetInputLayout(InputLayouts::Basic32);
pDeviceContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST); 
 
XMMATRIX W = World;
XMMATRIX worldInvTranspose = MathHelper::InverseTranspose(W);
XMMATRIX WorldViewProj = W * ViewProj;
XMMATRIX TexTransform = XMMatrixIdentity();
XMMATRIX ShadowTransform = W * XMLoadFloat4x4(&d3d->m_ShadowTransform);
 
// Transform NDC space [-1,+1]^2 to texture space [0,1]^2
XMMATRIX toTexSpace(
0.5f, 0.0f, 0.0f, 0.0f,
0.0f, -0.5f, 0.0f, 0.0f,
0.0f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.0f, 1.0f);
 
Effects::BasicFX->SetDirLights(Lights);
Effects::BasicFX->SetEyePosW(d3d->m_Cam.GetPosition());
 
if (mInfo.AlphaClip)
{
   if (mInfo.NumLights == 1)
   activeTech = Effects::BasicFX->Light1TexAlphaClipTech;
   else if (mInfo.NumLights == 2)
       activeTech = Effects::BasicFX->Light2TexAlphaClipTech;
   else if (mInfo.NumLights == 3)
   activeTech = Effects::BasicFX->Light3TexAlphaClipTech;
   else 
   activeTech = Effects::BasicFX->Light0TexAlphaClipTech;
}
else
{
if (mInfo.NumLights == 1)
   activeTech = Effects::BasicFX->Light1TexTech;
   else if (mInfo.NumLights == 2)
       activeTech = Effects::BasicFX->Light2TexTech;
   else if (mInfo.NumLights == 3)
   activeTech = Effects::BasicFX->Light3TexTech;
   else 
   activeTech = Effects::BasicFX->Light0TexTech;
 
}
 
if (!mInfo.BackfaceCulling)
pDeviceContext->RSSetState(RenderStates::NoCullRS);
 
 
Effects::BasicFX->SetShadowMap(d3d->GetShadowMap());
Effects::BasicFX->SetSsaoMap(d3d->m_Ssao->AmbientSRV());
Effects::BasicFX->SetWorld(W);
Effects::BasicFX->SetWorldInvTranspose(worldInvTranspose);
Effects::BasicFX->SetWorldViewProj(WorldViewProj);
Effects::BasicFX->SetWorldViewProjTex(WorldViewProj * toTexSpace);
Effects::BasicFX->SetTexTransform(TexTransform);
Effects::BasicFX->SetShadowTransform(ShadowTransform);
 
 
D3DX11_TECHNIQUE_DESC techDesc;
    activeTech->GetDesc(&techDesc);
 
float blendFactor[4] = {0.0f, 0.0f, 0.0f, 0.0f};
 
    for(UINT p = 0; p < techDesc.Passes; ++p)
    {
for (UINT i = 0; i < mModel.mSubsetCount; i++)
   {   
   Effects::BasicFX->SetMaterial(Materials[i]);
Effects::BasicFX->SetDiffuseMap(DiffuseMapSRV[i]);
 
if (mInfo.AlphaToCoverage)
pDeviceContext->OMSetBlendState(RenderStates::AlphaToCoverageBS, blendFactor, 0xffffffff);
 
   activeTech->GetPassByIndex(p)->Apply(0, pDeviceContext);
 
   mModel.Mesh.Draw(i);
 
if (mInfo.AlphaToCoverage)
   pDeviceContext->OMSetBlendState(0, blendFactor, 0xffffffff);
   }
}
 
if (!mInfo.BackfaceCulling)
   pDeviceContext->RSSetState(0);
}

I fixed the problem but SSAO is still bottleneck. (Performance problems.)

I reduced samples to 5 from 14 and blurring of image 2 times instead of 4 times + I'm skipping pixels that are too away from camera. ( if (p.z > 100) return 1.0f;) yet I only get 40 fps (at 1024x768 resoulution of screen and half of it for ssao map) when I'm very near to the model which uses SSAO.

We need to know the system specs as well. :)