Basic usage

Overview

Altus Denoiser uses information from two rendered images to generate a high quality denoised image. This guide will explain how to setup and render the inputs to Altus. There are two concepts that Altus uses to generate denoised outputs:

AOVs (Arbitrary Output Variables) provide a way to render any arbitrary shaded component into different images. Typically renderers will only produce a final color for each pixel of the image (known as the beauty pass, or RGB pass), but you can break out renders into their component parts such as indirect lighting, diffuse color, reflections, shadows, mattes, etc. and save them as files individually or layers as part of a multichannel/multilayer EXR. See Recommended AOVs for more information.

Two images (called buffers) must be generated for each image. It’s important that each buffer is rendered with a different sample seed so that they will have unique noise patterns. The variance between the two buffers is what Altus uses to remove noise. Without variance, there is not enough information to remove noise. See Buffers for more information.

For information on how to run Altus once the correct inputs have been created see Usage.

Youtube

Checkout our youtube page for videos, tutorials, and demo reels showing what Altus Denosier can do.

Guide

This guide will explain how to denoise a given scene and adjust some filter settings. Start by downloading the demo scene we will be using: <link>

Demo Contents

The demo scene zip contains two folders of images: b0 and b1. Each folder was rendered with a different seed to ensure that b0, b1 have different noise patterns. Each folder contains all the render passes (AOVs) recommended by Innobright: Recommended AOVs. We will be using these contents to denoise the beauty images.

One of the beauty render (b0):

../../../_images/b01.png

Denoise the Demo Scene:

To start lets denoise the demo scene using default Altus settings. First ensure that Altus has been setup properly.

Import images into Altus

Using the Import Wizard

This is the easiest way to import into Altus. Here you’ll select either “Import Folder” or “Import Images”. From there select the desired files you want to import for denoising. Once the files are selected hit “Open” and the files that were selected will be shown with their AOV’s. Organize the AOV’s so they match up correctly (this is indicated with a green check-mark over each pass). Once everything has the green check-mark you can then hit “Finished”.

Setting up the Config File

Another way to import images into Altus is by using a config file. Config files (.cfg) allow us to define the image paths along with any filter settings. In this guide we will be using a config file. For more info see Configuration Files.

First to define in a config file are the paths to the b0, b1 renders. Lets start with the beauty:

For example:

rgb-0=C:\Example\Files\Pass 1\animation_sequence_####.exr
rgb-1=C:\Example\Files\Pass 2\animation_sequence_####.exr

Now we can add the position pass and normals:

pos-0=C:\Example\Files\Pass 1\animation_sequence_####.exr
pos-1=C:\Example\Files\Pass 2\animation_sequence_####.exr

nrm-0=C:\Example\Files\Pass 1\animation_sequence_normals####.exr
nrm-1=C:\Example\Files\Pass 2\animation_sequence_normals####.exr

Finally, we rendered out an AOV for reflections. Lets add that as an extra AOV to Altus:

extra-0=C:\Example\Files\Pass 1\animation_sequence_normals####.exr
extra-1=C:\Example\Files\Pass 2\animation_sequence_normals####.exr

Now that we defined all the input images, we should specify where the output will be saved. There are a couple options for that, we will append ”–out-dir” to the config file:

out-dir=C:\tmp\output

All together the final config file should look like:

rgb-0=C:\Example\Files\Pass 1\animation_sequence_####.exr
rgb-1=C:\Example\Files\Pass 2\animation_sequence_####.exr
pos-0=C:\Example\Files\Pass 1\animation_sequence_####.exr
pos-1=C:\Example\Files\Pass 2\animation_sequence_####.exr
nrm-0=C:\Example\Files\Pass 1\animation_sequence_normals####.exr
nrm-1=C:\Example\Files\Pass 2\animation_sequence_normals####.exr
extra-0=C:\Example\Files\Pass 1\animation_sequence_normals####.exr
extra-1=C:\Example\Files\Pass 2\animation_sequence_normals####.exr
out-dir=C:\tmp\output

Running Altus

Now that we have a config file, we can use it to run Altus. To import a config file using Altus Studio: open the file drop down menu, select “Load” (Config file) and locate the desired config file you are wanting to import. Altus Studio will reconfigure to match the imported config file.

Denoise with Altus

To begin:: You have successfully uploaded your files and placed the AOV’s so they all have a green check-mark. The next step is to begin the process of denoising and this is achieved by locating the “Start Denoiser” button on the bottom right corner, click the button and Altus should begin to filter. Once it has completed the output image will be saved in the directory we specified with out-dir.

My denoised result:

../../../_images/altus1.png

Basic Filter Settings:

Once you are comfortable running Altus, you can experiment with the filter settings. See also Advanced usage for more options. The essential basic settings are as follows:

Window Radius

Specifies the dimension of the filtering window. The default of 10 means that the origin pixel, plus 10 pixels up, down, left, and right will be considered. That is, the filtering window will be a 21x21 box.

Decreasing the radius will result in faster denoising, but may leave more noise behind.

Increasing the radius will result in significantly slower denoising, possibly removing more noise at the risk of “over-smoothing” an image.

Generally, reducing the radius will be more noticeable visually than increasing it.

kc_1

This value scales how much color (beauty) will influence the small (detail) kernel blur. Low values will expose more detail at the risk of leaving noise behind.

kc_2

This value scales how much color (beauty) will influence the large (edge) kernel blur. Low values will expose more detail at the risk of leaving noise behind.

kc_3

This value is not used; it is present for legacy compatibility.

kc_4

Controls removal of residual noise.

kf

Controls the influence of feature AOVs (e.g. position, normals, etc) for all kernel sizes. Generally controls the trade-off between preserving edges and fine detail. Low values will expose more detail at the risk of leaving noise behind.

Denoise Again With Adjusted Filter Settings

Now that we understand the settings, lets try to change the settings on the image we denoised above. Still within the main interface, lets change the kc values and window radius on the input panel:

kc_1 = 0.25 kc_2 = 0.25 kf = 0.3 radius = 6

And the denoised output:

../../../_images/altus1.png

Final Notes

Congratulations on completing the basic usage tutorial for Altus Denoiser! If want to tweak Altus to perfection, see: Advanced usage.

Note

Explore our help site for more information on Altus and using Altus with third party software. Here are some places to get started:

For information on Altus Studio Animation.

For information on Altus Studio Output Options.

For information on Altus Command Line Denoiser (CLD) Basic usage.

To use Altus with other software see: Integration with Third Party Software.