The document provides instructions for installing and using Radeon ProRender (RPR) within Houdini. It discusses importing geometry and materials, assigning materials, setting render variables and settings, exporting for rendering, and using toon shading mode. The key steps are to install RPR, set the viewport to RPR, import geometry into a stage using SOP or scene import nodes, create materials in the material library, assign materials, add render variables and settings nodes, and export using the RPR export node.

1. Render Pool Manual
Radeon ProRender for Houdini

2. Radeon ProRender in Houdini - Contents
Installation
Viewing RPR in Houdini
SOP Import/ Scene Import
Object ID / Geometry Settings
Material Library / Assign Material
Material ID Properties
AOV / RPR Standard Render Vars
Render Settings
ToonTrace / Contour Mode
RPR Export
3
5
11
17
19
27
29
39
45
48
2

3. Installation
3

4. Installation – Automatic Installation
This is the easiest method
of installation, known as
the Automatic Method,
locate your Houdini Preference
directory and add the hdRpr package
that will point it to the
current directory.
When your hdrpr download is
complete, unpack the zip folder and
open the folder located inside.
Double-click on the
activateHoudiniPlugin executable.
A window should appear saying that
the plugin has been activated. Once
complete, open Houdini to confirm
that the installation was successful.
4

5. Viewing RPR in Houdini
5

6. Viewing RPR in Houdini
Radeon ProRender utilizes Houdini's Solaris Tools and
LOPS or Lighting Operator nodes, which work to
generate and modify Universal Scene Description
(USD) based scenes.
There are several workflows that allow you to use the
RPR plugin, but in each workflow, the viewport must
be set to the RPR perspective.
6

7. Viewing RPR in Houdini – Solaris desktop
Once you've opened Houdini, Houdini's desktop interface
is set to Build by default.
Go to Build in your 3D viewport and select the Solaris
desktop option.
This will change Houdini's desktop to the stage network,
as well as open the Scene Graph Tree and Scene Graph
Details panes.
In your 3D viewport's perspective
menu,
find and select the RPR option to
make it the active renderer.
BUILD > SOLARIS
7

8. Viewing RPR in Houdini – Stage Network View
Another way to utilize RPR's features is to simply switch
from the object network to the stage network from
the Network View pane.
Once again, setting the active renderer to RPR in the
perspective viewport.
NETWORK VIEW > Other Networks > Stage
8

9. Viewing RPR in Houdini – Perspective Viewport
If you have any issues with your viewport, you can always
select Restart Render in the perspective menu to
reset the stage.
Houdini GL Perspective
RPR Perspective
9

10. Viewing RPR in Houdini – LOP Network
LOP Network
You can also create a LOP Network node inside your
Object Network if you aren't working entirely in RPR to
create your scene.
Add the node and double click to enter the network.
Obj > TAB > LOP Network
10

11. SOP Import / Scene Import
11

12. SOP Import / Scene Import
SOP Import node
If your imported SOP data has subgroups to
separate the primitives for material assignment in
the Object Network, be sure to activate the
Subset Groups option in the Import Data sub
menu and list the geometry's group names with a
space in-between each.
The SOP import node imports geometry from the
Object network into a stage or LOP network.
find SOP Path and open the Operator chooser and
select the geometry you want.
SOP IMPORT > SOP Path >/obj/...
SOP IMPORT > Import Data > Subset
Groups
12

13. SOP Import / Scene Import
Scene Import node
The Scene import node is similar, but can also
import cameras and lights from the Object
network into the stage or LOP network.
SCENE IMPORT > Objects > /obj/...
To do the same for importing pre-
existing cameras and lights from the Object
network into the stage or LOP network, you can
select the Scene Import (Cameras) or (Lights)
nodes.
13

14. SOP Import / Scene Import - Merge
Merge LOP
The Merge node takes multiple inputs (in this
case, one or more USD layers) and merges them
into a stage containing one layer stack in the
output. This is useful when you want to combine
separate pieces of a scene graph, each authored
by a different chain of LOP nodes, into a unified
whole.
14

15. SOP Import / Scene Import - Sublayer
The Sublayer node imports from external USD and
USDA files or other LOP node chains into new
Stage or LOP network as sublayers or instances
that have already been made in other .hip files.
You can import USD elements separately or
import entire scenes using this layer.
Sublayer
SUBLAYER > Sublayer File > Desired File Path
15

16. SOP Import / Scene Import - Test Scenes
RPR for Houdini test scenes (including the scene
used in this tutorial) can be used for
comprehension and experimentation using basic
Houdini assets within a standard hdrpr
workflow. These test scenes can be found here:
Test Hdrpr Scenes
https://drive.google.com/file/d/1JrIgvimsk4siq
615nmJcA4ZAb8uVzTCu/view?usp=sharing
https://github.com/hshakula/hdRprDocs/tree/
master/asset/basicScene
Test Scene (Sphere Plane)
Test Scene (AMD Produced Basic Scene)
16

17. Object ID / Geometry Settings
17

18. Object ID / Geometry Settings
The Render Geometry Settings node
will apply renderer-specific geometry
settings to geometry in the scene
graph.
Having multiple objects in a scene will
require each of them to have this
node if you wish for each of them to
have separate Object IDs.
Setting the ID option in the RPR
Submenu will change the color of the
designated geometry randomly for
easy viewing.
Render Geometry Settings
PRIMITIVES > Desired object
path
ID > Desired Object ID Number
18

19. Material Library / Assign Material
19

20. Material Library/ Assign Material
Material Library
RPR Uber
RPR Toon
The Material Library node translates
shader VOP or Vector Operator nodes
into USD material primitives.
The RPR Uber Shader is a multi-purpose
shader intended for creating a wide range of real-
world materials.
It consolidates a number of components, or layers,
that group certain properties of physical materials.
The RPR Toon Shader is a shader intended for the
mimicry of cel-shaded color with sharp shadow
tones and highlights.
The USD UV Texture material can also be applied
to the color for mutliple materials. 20

21. Material Library/ Assign Material
Material Library
RPR Uber
OFF ON
• Color
Parameter for base RGB color
• Weight
Value for diffuse weight
• Roughness
Value for diffuse roughness
• Normal
Parameters for setting diffuse normal
The RPR Uber Shader is a multi-purpose shader and allows for reflective,
refractive, transparent, emissive and subsurface properties. The diffuse
is the default.
21

22. Material Library/ Assign Material
Material Library
RPR Toon
OFF ON
• Shadow Color
Parameter for Shadow base color
• Mid Level Mid Level Mix
Value between Mid and Shadow base
color
• Mid Color
Parameter for Mid base color
• HIghlight Level/ Highlight Level
Mix
Value between Mid and Highlight
base color
• HIghlight Color
Parameter for highlight base color
• Interpolation Mode
• Roughness
Value for Roughness parameter
The RPR Toon Shader does not allow for
special properties at this time.
22

23. Material Library/ Assign Material
Material Library Toon Shader Update
As of Hdrpr version 2.0.46, The RPR
Toon Shader has been updated to
include base RGB Color control
parameter.
23

24. Material Library/ Assign Material
Assign Material
/sphere3/ /sopimport1/
The Assign Material node will allow
you to take the Materials you've
setup in the Material Library and
apply their properties to your
primitives.
PRIMITIVES > Desired object
path
MATERIAL PATH > Desired
material path
24

25. Material Library/ Assign Material – Material Linker
Material Linker
/sphere3/ /rubbertoy1/
Similar to the Assign Material node,
the Material Linker node allows you
to assign materials to designated
geometry using rules you setup in the
node itself.
If the Material Linker is active, the
assignment should appear
automatically in the viewport.
MATERIALS > Drag Desired
Material > Desired geometry
path
25

26. Material Library/ Assign Material – MaterialX Library
RPR MaterialX Library Toon Shader Update
As of Hdrpr version 2.0.46, The RPR
Toon Shader has been updated to
include base RGB Color control
parameter.
The RPR Material Library is a
prebuilt directory with preset
materials that can be downloaded
from the Radeon ProRender
documentation website.
The Import Material function located
in the RPR dropdown menu will open
a new window will appear revealing
the library preset list, complete with
images showing each material's
characteristics.
26

27. Material ID Properties
27

28. Material ID Properties
RPR Material Properties
MATERIAL PATH > Desired
material path
The RPR Material Properties node will apply
renderer-specific material ID settings to the
designated Material path.
Having multiple materials in a scene will
require each of them to have this node if you
wish for each of them to have separate
Material IDs with separate numbers.
Setting the ID option will change the color of
the designated material randomly for easy
viewing.
ID > Desired Material ID Number
28

29. AOVs / RPR Standard Render Vars
29

30. AOVs / RPR Standard Render Vars
RPR Standard Render Vars
Render Variables in Houdini are
referring to Arbitrary Output
Variables, or AOVs.
AOVs can be extremely useful for
examining various aspects of a scene
and can aid post-production
processes.
To use these, add the RPR Standard
Render Vars node.
You will see a checklist in
your parameters pane that includes
multiple AOV modes.
Below is a demonstration to what
each AOV may look like in the
viewport.
Beauty
Albedo
30

31. AOVs / RPR Standard Render Vars
Camera Normal Depth Direct Diffuse Direct Illumination
Direct Reflect Geometric Normal Indirect Diffuse Indirect Illumination 31

32. AOVs / RPR Standard Render Vars
Indirect Reflect Material ID Normal Opacity
Primitive ID Refract UV World Coordinate 32

33. AOVs / RPR Standard Render Vars
Primitive ID Mask Material ID Mask Velocity Variance (Adaptive Sampling)
Reflection Catcher
Shadow Catcher
Emission 33

34. AOVs / RPR Standard Render Vars
RPR1 and RPR2 for Houdini do not currently
support Cryptomatte.
RPR2 does not currently support Ambient
Occlusion. Full (Legacy) or RPR1 is necessary for
this variable to be visible in the viewport.
Heterogeneous Volume and volumetrics are also
not currently visible in viewports with Full set as the
viewport renderer.
Depth passes are not visible in viewport until
render. Level adjustment is potentially necessary.
RPR Toon shader is not visible in RPR1 viewport or
render.
Full (RPR 2) and Full (Legacy)
34

35. AOVs / RPR Standard Render Vars
AOVs RPR1 RPR2
Cryptomatte X O
Ambient Occlusion O X
Beauty O O
Albedo O O
Depth O O
Shading Normal O O
Camera Normal O O
Texture Coordinate O O
Direct Illumination O O
Indirect Illumination O O
Direct Diffuse O O
Indirect Diffuse O O
Direct Reflect O O
Indirect Reflect O O
AOVs RPR1 RPR2
Refract O O
Volume X X
Emission O O
Background O O
Shadow Catcher O O
Reflection Catcher O O
Geometric Normal O O
View Space Shading
Normal
X X
Variance (Adaptive
Sampling)
O O
Opacity O O
World Coordinate O O
Primitive ID O O
Material ID O O
AOVs RPR1 RPR2
Primitive ID Mask O O
Material ID Mask O O
Velocity O O
35

36. AOVs / RPR Standard Render Vars – Motion Blur
Though workflows may vary, achieving a Motion
Blur effect in RPR for Houdini is possible using any
node capable of changing a primitive's transform.
One example of a typical workflow that allows for
this is the Xform or Createxform node.
This node belongs to a class of nodes that create or
edit USD prims directly. This node operates in
Create mode or Edit mode.
Xform
Transform
Another example of a typical workflow to achieve a
Motion Blur effect is using the Transform
node. This node edit the transforms of USD
primitives.
36

37. AOVs / RPR Standard Render Vars – Motion Blur
Xform
Set the desired start frame using the Set Keyframe
option or the Keyframe button in the timeline.
Set your desired Translate parameter.
Set the desired end frame by scrubbing the
timeline or setting the Global Animation End
Frame.
Set your desired Translate parameter.
CREATEXFORM > Translate >
(x,y,z)
PRIMITIVE PATH > Desired geometry
After adding the Xform node, set the Primitive path to
the desired geometry.
37

38. AOVs / RPR Standard Render Vars – Motion Blur
Transform
Set the desired start frame using the Set Keyframe
option or the Keyframe button in the timeline.
Set your desired Translate parameter.
Set the desired end frame by scrubbing the
timeline or setting the Global Animation End
Frame.
Set your desired Translate parameter.
TRANSFORM > Translate > (x,y,z)
PRIMITIVES > Desired geometry/collection
Similar to the Createxform node process, after adding
the Transform node, set the Primitive path to the
desired geometry.
38

39. Render Settings
39

40. Render Settings
Render Product
Once you've set your RPR Render
Vars node, you'll need to add the
Render Product node.
The Render Product node sets your
variables, your camera and your
output resolution.
First, set your Ordered Render Vars
parameter by establishing the Render
Variables that correspond to the
AOVs you checked off in your Render
Vars node.
ORDERED RENDER VARS>
/Render/Products/Vars/*
40

41. Render Settings
Render Settings
The Render Settings node is what
ProRender looks at when it exports its file to be
rendered using Render Pool or your renderer of
choice.
It allows you to set the Render Quality and
Render Mode that will be displayed in the final
export.
In the Standard Submenu, set your camera and
your output resolution.
RENDER SETTINGS > RPR Submenu
41

42. Render Settings
Render Settings
Max Settings
Value of maximum number of
samples to render for each pixel
Max Ray Depth
Value of maximum Ray Depth in
viewport
Diffuse Ray Depth
Value of maximum number of time a
light ray can be bounced off diffuse
surfaces
Glossy Ray Depth
Value of the maximum number of ray
bounces from specular surfaces
By default, some settings are greyed out and set to
Do Nothing. To change a setting, set it to Set or
Create.
42

43. Render Settings
Render Settings
Refraction Ray Depth
Value of the maximum number
of times that a light ray can
be refracted by clear
transparent materials, such as glass
Glossy Refraction Ray Depth
Value of the maximum number
of times that a light ray can be
refracted by matte refractive
materials, such as semi-frosted glass
Shadow Ray Depth
Value of accuracy of shadows cast
by transparent objects
43

44. Render Settings
Render Settings
Ray Cast Epsilon
sets an offset used to move light
rays away from the geometry in
your scene. Used for ray-
surface intersection calculations
Clamp Fireflies
Radiance clamping to prevent noise
Radiance
Value of the maximum brightness
of samples in your scene
Interactive Resolution Downscale
Controls how much
rendering resolution is downscaled in
the viewport
44

45. ToonTrace / Contour Mode
45

46. ToonTrace / Contour Mode
Render Settings
To activate the ToonTrace mode in
the viewport, Go to the Render
Mode
in the RPR Submenu and switch from
Global Illumination to Contour.
RPR > Render Mode >
Contour
Contour OFF Contour ON
46

47. ToonTrace / Contour Mode
Render Settings
Once Contour mode is activated,
a ToonTrace (Contour Settings)
submenu will appear underneath the
Render Mode. Here is where you will
be able to turn on Antialiasing,
and change the Linewidth, Normal
Threshold, Primitive ID and Material
ID Linewidth.
Adjustment Examples
47

48. RPR Export
48

49. RPR Export
the RPR Export node is the last
node necessary to complete the node
tree.
First, enter a valid Export Path for the
.rpr output file in your directory of
your choice. Be sure to add the
.rpr suffix to the end of your output
filename.
Set your Render Settings to your
render settings path.
If you're animating a camera, or
running a simulation, be sure to set
the Valid Frame Range to
Render Specific Frame Range.
EXPORT PATH > Desired file name.rpr
If your exporting an animation, be sure to include .$F4 after
your file name and before the .rpr output format.
RENDER TO DISK > Begin RPR Export
49

50. RPR Export
Once rendering is complete, check
the folder you specified in your
Windows Explorer, and you should
see your completed exported files.
You should have and .RPR file, and
.JSON file and several .RPRSB files
located in the desired export folder.
RPR files are the geometry data per
frame.
RPRSB files refer to texture,
geometry, and material cache files.
.JSON files record all other
information, including your
designated Render Variables.
50

51. RPR Export
Internal rendering within Houdini is
also possible. The USD Render ROP
node writes the USD generated by a
LOP network to a temp file, then
launches an external process (by
default, HUSK) to render an image or
image sequence from the USD.
Similar to RPR Export, if you're animating
a camera, or running a simulation, be
sure
to set the Valid Frame Range to
Render Specific Frame Range.
USD Render ROP
Renderer > RPR
Set the desired Renderer to RPR before selecting your Render
Settings.
51

52. RPR Export
Set your Render Settings to your render settings path.
The Render command is automatically set to husk. There is
no need to change this.
USD Render ROP
If your exporting an animation, be sure to include .$F4
after your file name and before the output format.
OVERRIDE OUTPUT IMAGE > Desired file name. * (.png, .exr,…)
52

53. RPR Export
Saving your file to disk will render out your beauty
AOV as a single file or a sequence of files if you've set
your animation output correctly. Rendering to MPlay
allows you to view your image or sequence once
rendering is complete in the MPlay Viewer, a separate
render viewing window. You can also switch between
the designated Render Variables or AOVs and save
them individually.
USD Render ROP
When you are ready, you can select
Render to Disk or Render to MPlay.
MPlay Viewer
53