From 99174e4e5fb4b7079da80b35a6dfd68f3fd56a1c Mon Sep 17 00:00:00 2001 From: lbavoil Date: Fri, 25 Mar 2016 13:01:54 +0100 Subject: GFSDK_HBAO+_distro_r3.0_cl20573789 --- doc/product.html | 403 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 403 insertions(+) create mode 100644 doc/product.html (limited to 'doc/product.html') diff --git a/doc/product.html b/doc/product.html new file mode 100644 index 0000000..09f3ff3 --- /dev/null +++ b/doc/product.html @@ -0,0 +1,403 @@ + + + + + + + + + NVIDIA HBAO+ 3.0. — NVIDIA HBAO+ 3.0. documentation + + + + + + + + + + + + + + + + + + + +
+
+ +
+
+
+
+
+

Table Of Contents

+ +

Previous topic

+

NVIDIA HBAO+

+

Next topic

+

Change Log

+ + +
+
+
+
+ +
+

NVIDIA HBAO+ 3.0.

+
+

Overview

+

HBAO+ is a SSAO algorithm designed to achieve high GPU efficiency. +The algorithm is based on HBAO [Bavoil and Sainz 2008], with the following differences:

+
    +
  1. To minimize cache trashing, HBAO+ does not use any randomization texture. Instead, the algorithm uses an Interleaved Rendering approach, generating the AO in multiple passes with a unique jitter value per pass [Bavoil and Jansen 2013].
    2. +
  2. To avoid over-occlusion artifacts, HBAO+ uses a simpler AO approximation than HBAO, similar to “Scalable Ambient Obscurance” [McGuire et al. 2012] [Bukowski et al. 2012].
    3. +
  3. To minimize flickering, the HBAO+ is always rendered in full resolution, from full-resolution depths.
    4. +
+_images/hbao-plus-in-tom-clancys-splinter-cell-blacklist-2.jpg +
+
+

Package

+

doc/—this documentation page.

+

lib/—header file, import libraries and DLLs, for Win32, Win64, Mac OS X and Linux.

+

samples/—source for sample applications demonstrating NVIDIA HBAO+.

+
+
+

Getting Started

+
    +

  1. INITIALIZE THE LIBRARY:

    +
    GFSDK_SSAO_CustomHeap CustomHeap;
+CustomHeap.new_ = ::operator new;
+CustomHeap.delete_ = ::operator delete;
+
+GFSDK_SSAO_Status status;
+GFSDK_SSAO_Context_D3D11* pAOContext;
+status = GFSDK_SSAO_CreateContext_D3D11(pD3D11Device, &pAOContext, &CustomHeap);
+assert(status == GFSDK_SSAO_OK); // HBAO+ requires feature level 11_0 or above
    +
    +
    2. +

  2. SET INPUT DEPTHS:

    +
    GFSDK_SSAO_InputData_D3D11 Input;
+Input.DepthData.DepthTextureType = GFSDK_SSAO_HARDWARE_DEPTHS;
+Input.DepthData.pFullResDepthTextureSRV = pDepthStencilTextureSRV;
+Input.DepthData.ProjectionMatrix.Data = GFSDK_SSAO_Float4x4(pProjectionMatrix);
+Input.DepthData.ProjectionMatrix.Layout = GFSDK_SSAO_ROW_MAJOR_ORDER;
+Input.DepthData.MetersToViewSpaceUnits = SceneScale;
    +
    +
    3. +

  3. SET AO PARAMETERS:

    +
    GFSDK_SSAO_Parameters_D3D11 Params;
+Params.Radius = 2.f;
+Params.Bias = 0.1f;
+Params.PowerExponent = 2.f;
+Params.Blur.Enable = true;
+Params.Blur.Radius = GFSDK_SSAO_BLUR_RADIUS_4;
+Params.Blur.Sharpness = 16.f;
    +
    +
    4. +

  4. SET RENDER TARGET:

    +
    GFSDK_SSAO_Output_D3D11 Output;
+Output.pRenderTargetView = pOutputColorRTV;
+Output.Blend.Mode = GFSDK_SSAO_OVERWRITE_RGB;
    +
    +
    5. +

  5. RENDER AO:

    +
    status = pAOContext->RenderAO(pD3D11Context, Input, Params, Output);
+assert(status == GFSDK_SSAO_OK);
    +
    +
    6. +
+
+
+

Data Flow

+
+

Input Requirements

+
    +
  • The library has entry points for D3D11, D3D12 and GL3.2+.
    • +
  • Requires a depth texture to be provided as input, along with associated projection info.
    • +
  • Optionally, can also take as input a GBuffer normal texture associated with the input depth texture:
      +
    • Can add normal-mapping details to the AO.
      • +
    • Can be used to fix normal reconstruction artifacts with dithered LOD dissolves.
      • +
    • But makes the integration more complex. We recommend starting with input normals disabled.
      • +
    +
    • +
  • Optionally, can also take as input a viewport rectangle associated with the input textures:
      +
    • Defines a sub-area of the input & output full-resolution textures to be sourced and rendered to.
      • +
    • The library re-allocates its internal render targets if the Viewport.Width or Viewport.Height changes for a given AO context.
      • +
    +
    • +
+
+
+

MSAA Support

+
    +
  • Requirements
      +
    • The input depth & normal textures are required to have matching dimensions and MSAA sample count.
      • +
    • The output render target can have arbitrary dimensions and MSAA sample count.
      • +
    +
    • +
  • Per-Pixel AO Algorithm
      +
    • If the input textures are MSAA, only sample 0 is used to render the AO.
      • +
    • If the output render target is MSAA, a per-pixel AO value is written to all samples.
      • +
    • In practice, we have found this strategy to not cause any objectionable artifacts, even when using HBAO+ with TXAA.
      • +
    +
    • +
+
+
+

HBAO+ Pipeline

+_images/pipeline_without_input_normals.png +_images/pipeline_with_input_normals.png +
+
+

Occlusion Samples

+
    +
  • For each pixel, 32 occlusion samples are taken in a variable-radius disk, with a minimum of 4 full-resolution pixels between the center pixel and the sample coordinates.
    • +
  • The 8 nearest samples to the center pixel are weighted by the NearAO parameter.
    • +
  • The other samples are weighted by the FarAO parameter.
    • +
+
+
+
+

Parameters

+
+

AO Radius

+
+
Definition
+
For a given AO receiver point P and AO Radius R, sample point S is ignored if ||P-S|| > R
+
Impact on search area
+
The AO radius is a multiplier for the screen-space search radius, and the number of samples is fixed. So if the AO radius is too large, under-sampling artifacts may appear.
+
+_images/AO_Radius_1.png +_images/AO_Radius_4.png +
+
+

MetersToViewSpaceUnits

+

If you are not sure what to set this value to, you can:

+
    +
  • Set the AO Radius parameter to 1.0 and
    • +
  • Increase MetersToViewSpaceUnits until the AO looks like it’s being cast up to 1 meter away
    • +
+

MetersToViewSpaceUnits is used internally

+
    +
  • To convert the AO radius parameter from meters to view-space units
    • +
  • To adjust the blur sharpness parameter
    • +
+
+
+

Power Exponent

+
    +
  • The PowerExponent parameter controls the darkness of the final AO: FinalAO = pow(AO, PowerExponent).
    • +
  • Typical PowerExponent values are in the range [2.0, 3.0].
    • +
+
+
+

AO Bias

+
    +
  • The AO Bias parameter can be used to hide low-tessellation artifacts
    • +
  • Can also help reducing false-occlusion artifacts near screen borders
    • +
  • It weights the AO contributions more strongly for samples towards the normal direction
    • +
+_images/AOBias_0_0.png +_images/AOBias_0_3.png +
+
+

Foreground AO

+
    +
  • When this feature is enabled, the screen-space AO kernel radius is:
      +
    • inversely proportional to ViewDepth for ViewDepth > ForegroundViewDepth
      • +
    • uniform in screen-space for ViewDepth <= ForegroundViewDepth (instead of getting arbitrarily large)
      • +
    +
    • +
  • To tune the ForegroundViewDepth parameter
      +
    • Start with ForegroundViewDepth = 0.f
      • +
    • Increase the ForegroundViewDepth to get less closer-scale occlusion on the foreground objects.
      • +
    +
    • +
+_images/ForegroundAO_OFF.png +_images/ForegroundAO_ON.png +
+
+

Background AO

+
    +
  • When this feature is enabled, the screen-space AO kernel radius is:
      +
    • inversely proportional to ViewDepth for ViewDepth < BackgroundViewDepth
      • +
    • uniform in screen-space for ViewDepth >= BackgroundViewDepth (instead of falling off to zero).
      • +
    +
    • +
  • To tune the BackgroundViewDepth parameter
      +
    • Start from a very large BackgroundViewDepth value (e.g. the camera’s ZFar)
      • +
    • Decrease the BackgroundViewDepth to get larger-scale occlusion in the background.
      • +
    +
    • +
+_images/BackgroundAO_OFF.png +_images/BackgroundAO_ON.png +
+
+

AO Blur

+
    +
  • Optional cross-bilateral filter
      +
    • To remove jittered-sampling artifacts (noise)
      • +
    • To hide under-sampling artifacts (banding) & reduce jittering
      • +
    +
    • +
  • 3 Modes
      +
    • No Blur
      • +
    • Blur Radius 2
      • +
    • Blur Radius 4
      • +
    +
    • +
+_images/No_Blur.png +_images/Blur_Radius_4.png +
+
+

Blur Sharpness

+

The greater the sharpness parameter, the more the blur preserves edges

+_images/Blur_Sharpness_0.png +_images/Blur_Sharpness_8.png +
+
+
+

Integration Time Estimates

+
    +
  • Initial integration (for a rendering engineer)
      +
    • <1 man-day with no input normals
      • +
    • 1-2 man-days with input normals
      • +
    +
    • +
  • Initial parameter tuning
      +
    • <1 man-hour
      • +
    • Tuning the parameter should be quick once the input data are correctly fed into the library
      • +
    • The same HBAO+ parameters may be used globally across the whole game
      • +
    +
    • +
+
+ +
+ + +
+
+
+
+
+
+
+ +
+
+ + + + \ No newline at end of file -- cgit v1.2.3