SSAO TOP

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Summary
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The SSAO TOP performs Screen Space Ambient Occlusion on the output of a Render TOP or Render Pass TOP. Because this technique requires access to the Depth Buffer, no other TOP can be in between the Render/RenderPass TOP and the SSAO TOP. Screen Space Ambient Occlusion is a real-time rendering trick that creates an approximation of ambient occlusion by using the Depth Buffer of the rendered scene. It is done as 2D post-processes, so the complexity of the scene has no bearing on how expensive it is. This is in comparison to true ambient occlusion which becomes more expensive with each new object that is rendered. There are two parts to a SSAO technique. First a SSAO pass is done that determines how much ambient occlusion each pixel is affected by. This result tends to be very noisy. A blur operation is then performed to even out this noise.

PythonIcon.pngssaoTOP_Class


Parameters - SSAO Page

Quality quality - - Determines the visual quality of the results. The higher the quality, the more computationally expensive it is.

  • Low low -
  • Medium medium -

Sample Directions sampledirs - For each pixel, rays are sent out in random directions to see if there is a surface nearby that would occlude the ambient light to this pixel. This parameter controls how many rays are sent out per pixel.

Sample Steps samplesteps - Since this is a 2D pixel-based operation, the rays need to sample multiple neighboring pixels along its path to check for points of interest. This parameter controls how many of these samples each ray does.

Surface Avoid Angle surfaceavoid - This parameter biases the angle of the rays so they don't travel too close to the plane that the starting point lays on (as determined by the point's normal).  

SSAO Pass Resolution ssaopassres - - The SSAO pass can be set to Full, Half, or Quarter the resolution of the input image.

  • Full full -
  • Half half -
  • Quarter quarter -

SSAO Radius ssaoradius - The distance it searches from the current point for occluders (in object space units).  

Contrast contrast - Controls the contrast of the SSAO contribution.  

Attenuation attenuation - Controls the attenuation of the ambient lighting.  

Edge Threshold edgethresh - To avoid the ambient occlusion from bleeding across the edges of objects onto other objects, an edge detect is done using the depth buffer to figure where one object ends and the next one begins. This parameter controls how sensitive the edge detection is.  

Blur Radius blurradius - The amount of blur in pixels.  

Blur Sharpness blursharpness - Controls the sharpness of the blur operation.  

Combine with Color combinewithcolor - By default the final ambient occlusion result will be multiplied by the color output of the Render TOP. You can just output the ambient occlusion results by turning this parameter off.


Parameters - Common Page

Output Resolution outputresolution - - quickly change the resolution of the TOP's data.

  • Use Input useinput - Uses the input's resolution.
  • Eighth eighth - Multiply the input's resolution by that amount.
  • Quarter quarter - Multiply the input's resolution by that amount.
  • Half half - Multiply the input's resolution by that amount.
  • 2X 2x - Multiply the input's resolution by that amount.
  • 4X 4x - Multiply the input's resolution by that amount.
  • 8X 8x - Multiply the input's resolution by that amount.
  • Fit Resolution fit - Multiply the input's resolution by that amount.
  • Limit Resolution limit - Multiply the input's resolution by that amount.
  • Custom Resolution custom - Enables the Resolution parameter below, giving direct control over width and height.

Resolution resolution - Enabled only when the Resolution parameter is set to Custom Resolution. Some Generators like Constant and Ramp do not use inputs and only use this field to determine their size. The drop down menu on the right provides some commonly used resolutions.

Resolution Menu resmenu -

Use Global Res Multiplier resmult - Uses the Global Resolution Multiplier found in Edit>Preferences>TOPs. This multiplies all the TOPs resolutions by the set amount. This is handy when working on computers with different hardware specifications. If a project is designed on a desktop workstation with lots of graphics memory, a user on a laptop with only 64MB VRAM can set the Global Resolution Multiplier to a value of half or quarter so it runs at an acceptable speed. By checking this checkbox on, this TOP is affected by the global multiplier.

Output Aspect outputaspect - - Sets the image aspect ratio allowing any textures to be viewed in any size. Watch for unexpected results when compositing TOPs with different aspect ratios. (You can define images with non-square pixels using xres, yres, aspectx, aspecty where xres/yres != aspectx/aspecty.)

  • Use Input useinput - Uses the input's aspect ratio.
  • Resolution resolution - Uses the aspect of the image's defined resolution (ie 512x256 would be 2:1), whereby each pixel is square.
  • Custom Aspect custom - Lets you explicitly define a custom aspect ratio in the Aspect parameter below.

Aspect aspect- - Use when Output Aspect parameter is set to Custom Aspect.

Aspect1 aspect1 -


Aspect2 aspect2 -

Aspect Menu armenu -

Input Smoothness inputfiltertype - - This controls pixel filtering on the input image of the TOP.

  • Nearest Pixel nearest - Uses nearest pixel or accurate image representation. Images will look jaggy when viewing at any zoom level other than Native Resolution.
  • Interpolate Pixels linear - Uses linear filtering between pixels. This is how you get TOP images in viewers to look good at various zoom levels, especially useful when using any Fill Viewer setting other than Native Resolution.
  • Mipmap Pixels mipmap - Uses mipmap filtering when scaling images. This can be used to reduce artifacts and sparkling in moving/scaling images that have lots of detail.

Fill Viewer fillmode - - Determine how the TOP image is displayed in the viewer. NOTE:To get an understanding of how TOPs work with images, you will want to set this to Native Resolution as you lay down TOPs when starting out. This will let you see what is actually happening without any automatic viewer resizing.

  • Use Input useinput - Uses the same Fill Viewer settings as it's input.
  • Fill fill - Stretches the image to fit the edges of the viewer.
  • Fit Horizontal width - Stretches image to fit viewer horizontally.
  • Fit Vertical height - Stretches image to fit viewer vertically.
  • Fit Best best - Stretches or squashes image so no part of image is cropped.
  • Fit Outside outside - Stretches or squashes image so image fills viewer while constraining it's proportions. This often leads to part of image getting cropped by viewer.
  • Native Resolution nativeres - Displays the native resolution of the image in the viewer.

Viewer Smoothness filtertype - - This controls pixel filtering in the viewers.

  • Nearest Pixel nearest - Uses nearest pixel or accurate image representation. Images will look jaggy when viewing at any zoom level other than Native Resolution.
  • Interpolate Pixels linear - Uses linear filtering between pixels. Use this to get TOP images in viewers to look good at various zoom levels, especially useful when using any Fill Viewer setting other than Native Resolution.
  • Mipmap Pixels mipmap - Uses mipmap filtering when scaling images. This can be used to reduce artifacts and sparkling in moving/scaling images that have lots of detail.

Passes npasses - Duplicates the operation of the TOP the specified number of times. Making this larger than 1 is essentially the same as taking the output from each pass, and passing it into the first input of the node and repeating the process. Other inputs and parameters remain the same for each pass.

Channel Mask chanmask - Allows you to choose which channels (R, G, B, or A) the TOP will operate on. All channels are selected by default.

Pixel Format format - - Format used to store data for each channel in the image (ie. R, G, B, and A). Refer to Pixel Formats for more information.

  • Use Input useinput - Uses the input's pixel format.
  • 8-bit fixed (RGBA) rgba8fixed - Uses 8-bit integer values for each channel.
  • sRGB 8-bit fixed (RGBA) srgba8fixed - Uses 8-bit integer values for each channel and stores color in sRGB colorspace.
  • 16-bit float (RGBA) rgba16float - Uses 16-bits per color channel, 64-bits per pixel.
  • 32-bit float (RGBA) rgba32float - Uses 32-bits per color channel, 128-bits per pixels.
  • 10-bit RGB, 2-bit Alpha, fixed (RGBA) rgb10a2fixed - Uses 10-bits per color channel and 2-bits for alpha, 32-bits total per pixel.
  • 16-bit fixed (RGBA) rgba16fixed - Uses 16-bits per color channel, 64-bits total per pixel.
  • 11-bit float (RGB), Positive Values Only rgba11float - A RGB floating point format that has 11 bits for the Red and Green channels, and 10-bits for the Blue Channel, 32-bits total per pixel (therefore the same memory usage as 8-bit RGBA). The Alpha channel in this format will always be 1. Values can go above one, but can't be negative. ie. the range is [0, infinite).
  • 16-bit float (RGB) rgb16float -
  • 32-bit float (RGB) rgb32float -
  • 8-bit fixed (Mono) mono8fixed - Single channel, where RGB will all have the same value, and Alpha will be 1.0. 8-bits per pixel.
  • 16-bit fixed (Mono) mono16fixed - Single channel, where RGB will all have the same value, and Alpha will be 1.0. 16-bits per pixel.
  • 16-bit float (Mono) mono16float - Single channel, where RGB will all have the same value, and Alpha will be 1.0. 16-bits per pixel.
  • 32-bit float (Mono) mono32float - Single channel, where RGB will all have the same value, and Alpha will be 1.0. 32-bits per pixel.
  • 8-bit fixed (RG) rg8fixed - A 2 channel format, R and G have values, while B is 0 always and Alpha is 1.0. 8-bits per channel, 16-bits total per pixel.
  • 16-bit fixed (RG) rg16fixed - A 2 channel format, R and G have values, while B is 0 always and Alpha is 1.0. 16-bits per channel, 32-bits total per pixel.
  • 16-bit float (RG) rg16float - A 2 channel format, R and G have values, while B is 0 always and Alpha is 1.0. 16-bits per channel, 32-bits total per pixel.
  • 32-bit float (RG) rg32float - A 2 channel format, R and G have values, while B is 0 always and Alpha is 1.0. 32-bits per channel, 64-bits total per pixel.
  • 8-bit fixed (A) a8fixed - An Alpha only format that has 8-bits per channel, 8-bits per pixel.
  • 16-bit fixed (A) a16fixed - An Alpha only format that has 16-bits per channel, 16-bits per pixel.
  • 16-bit float (A) a16float - An Alpha only format that has 16-bits per channel, 16-bits per pixel.
  • 32-bit float (A) a32float - An Alpha only format that has 32-bits per channel, 32-bits per pixel.
  • 8-bit fixed (Mono+Alpha) monoalpha8fixed - A 2 channel format, one value for RGB and one value for Alpha. 8-bits per channel, 16-bits per pixel.
  • 16-bit fixed (Mono+Alpha) monoalpha16fixed - A 2 channel format, one value for RGB and one value for Alpha. 16-bits per channel, 32-bits per pixel.
  • 16-bit float (Mono+Alpha) monoalpha16float - A 2 channel format, one value for RGB and one value for Alpha. 16-bits per channel, 32-bits per pixel.
  • 32-bit float (Mono+Alpha) monoalpha32float - A 2 channel format, one value for RGB and one value for Alpha. 32-bits per channel, 64-bits per pixel.


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An Operator Family that creates, composites and modifies images, and reads/writes images and movies to/from files and the network. TOPs run on the graphics card's GPU.

The width and height of an image in pixels. Most TOPs, like the Movie File In TOP can set the image resolution. See Aspect Ratio for the width/height ratio of an image, taking into account non-square pixels.

The viewer of a node can be (1) the interior of a node (the Node Viewer), (2) a floating window (RMB->View... on node), or (3) a Pane that graphically shows the results of an operator.

A CHOP outputs one or more channels, where a channel is simply a sequence of numbers, representing motion, audio, etc. Channels are passed between CHOPs in TouchDesigner networks. See also Export.