Trace Sets - Samples and tutorial
Posted: Thu Jul 31, 2025 10:50 pm
Trace Sets
(available from version 2026.1 Alpha3 - 26.01)
ref:
viewtopic.php?t=84311
Trace sets allow geometry to be made invisible to other geometry. For example, an object’s reflection can be hidden in another reflective object, or an object can be prevented from casting shadows on another object.
Trace sets are set up via object layer nodes (with Octane Geometry modifier) and apply to the geometry that belongs to the object layer. Object layers can belong to zero or more trace sets (currently limited to 31) and different object layers can belong to the same trace set.
Each object layer can use any number of trace set exclusion rules, which can apply to reflection, refraction, diffuse and shadow ray bounce types
and can optionally apply to multiple bounces rather than just the next one. The combination of these two makes this feature quite powerful and versatile.
Current limitations:
Trace sets are ignored for dirt, round edges, post volume and Gaussian splats
Visibility rules on volumes are not applied (but volumes themselves can still be excluded).
Trace sets in 3dsMax
Trace sets are enabled by adding an Octane Geometry modifier to the objects.
2 new textures (in Maps / Octane / Geometry / Utility) are used to define the rules to apply:
A 'Trace set visibility group' texture, that contains 1 or more rules.
A 'Trace set visibility rule' texture
---------------------------
Samples
TraceSet_Sample1_Reflection.max
You can see how the red sphere is excluded from reflections in the mirror while the rest of objects are still displayed.
Sphere001 has an Octane Geometry modifier with Trace Sets set to the keyword 'red'
mirror01 has an Octane Geometry modifier with a Trace Set Group texture 'Map #0' (a 'Trace set visibility group' texture)
'Map #0' has a single rule : Map #1 (a 'Trace set visibility rule' texture)
'Map #1' has the 'red' keyword, matching the keyword of Sphere001
All the bounce types are enabled, but in this case, the Reflection is the one that prevents the rays from the sphere to be reflected in the mirror.
TraceSet_Sample2_CastShadow.max
The Teapot002 has a modifier with the keyword 'blue'
The Box001 has a modifier with a rule (group Map #7, rule Map #8) that exclude 'blue'.
All the bounce types are enabled, but in this case, the Shadow is the one that prevents the shadow rays from the teapot to be cast by the box.
TraceSet_Sample3_light.max
OctaneLight_001 (emitting a red color) has a modifier with the keyword 'oLight1'
The sphere on the right, Sphere001, has a rule (group Map #5, rule Map #6) that exclude 'oLight1'
All the bounce types are enabled, but in this case, the Shadow is the one that prevents the red color from OctaneLight_001 to be received by the sphere.
Sphere001 only receive light from the blue light (OctaneLight_002)
Sphere002 has no visibility rule, and receive both blue and red lights.
(available from version 2026.1 Alpha3 - 26.01)
ref:
viewtopic.php?t=84311
Trace sets allow geometry to be made invisible to other geometry. For example, an object’s reflection can be hidden in another reflective object, or an object can be prevented from casting shadows on another object.
Trace sets are set up via object layer nodes (with Octane Geometry modifier) and apply to the geometry that belongs to the object layer. Object layers can belong to zero or more trace sets (currently limited to 31) and different object layers can belong to the same trace set.
Each object layer can use any number of trace set exclusion rules, which can apply to reflection, refraction, diffuse and shadow ray bounce types
and can optionally apply to multiple bounces rather than just the next one. The combination of these two makes this feature quite powerful and versatile.
Current limitations:
Trace sets are ignored for dirt, round edges, post volume and Gaussian splats
Visibility rules on volumes are not applied (but volumes themselves can still be excluded).
Trace sets in 3dsMax
Trace sets are enabled by adding an Octane Geometry modifier to the objects.
2 new textures (in Maps / Octane / Geometry / Utility) are used to define the rules to apply:
A 'Trace set visibility group' texture, that contains 1 or more rules.
A 'Trace set visibility rule' texture
---------------------------
Samples
TraceSet_Sample1_Reflection.max
Sphere001 has an Octane Geometry modifier with Trace Sets set to the keyword 'red'
mirror01 has an Octane Geometry modifier with a Trace Set Group texture 'Map #0' (a 'Trace set visibility group' texture)
'Map #0' has a single rule : Map #1 (a 'Trace set visibility rule' texture)
'Map #1' has the 'red' keyword, matching the keyword of Sphere001
All the bounce types are enabled, but in this case, the Reflection is the one that prevents the rays from the sphere to be reflected in the mirror.
- Trace set - visibility rule.jpg (11.44 KiB) Viewed 28 times
TraceSet_Sample2_CastShadow.max
The Box001 has a modifier with a rule (group Map #7, rule Map #8) that exclude 'blue'.
All the bounce types are enabled, but in this case, the Shadow is the one that prevents the shadow rays from the teapot to be cast by the box.
TraceSet_Sample3_light.max
The sphere on the right, Sphere001, has a rule (group Map #5, rule Map #6) that exclude 'oLight1'
All the bounce types are enabled, but in this case, the Shadow is the one that prevents the red color from OctaneLight_001 to be received by the sphere.
Sphere001 only receive light from the blue light (OctaneLight_002)
Sphere002 has no visibility rule, and receive both blue and red lights.