Update v1.4 is fully dedicated to random walk subsurface scattering. We added many new features with an overall speedup and a dedicated workflow for indirect rays. Briefly :  Rayleigh scattering Mie Scattering Similarity theory Albedo remapping Diffuse contrast Indirect sampling Continuation rays Overall speedup Added new demo scenes to test updated features and subsurface scattering.[…]

We’ve implemented new exciting features for the SSS random walk shaders. In the while there have also been many optimizations on how sampling is used regard direct vs indirect lighting. We’ve discovered that for the majority of cases we don’t need the extra complexity we introduce with guided (Dwivedi) sampling for indirect sampling/lighting, resulting in[…]

With v1.3 update, we’ve refined rombo reflection shaders : added a new bump mode to romboReflectGeneralized we called ‘Symmetrical’ previous ‘Analitycal’ bump mode has been renamed ‘Tangent’ added a new param ‘Rough IOR’ to romboReflectGeneralized fixed some rare NANs with romboReflect shaders sped up some internal computations Added a new utility node, romboWIFLoader. Added romboTonemapper,[…]

WIF loader is a companion shader for our romboFabricWoven material. Because sometimes we may want to use external nodes to further model things, we’ve added a romboWIFLoader utility that matches romboFabricWoven patterns for increased flexibility in modeling bumps and displacements for example. It can also be used standalone for pattern modelling and general WIF (Weaving[…]

We implemented various tonemap operators for the shader graph so they can be used for color correction or any other task that involves colors, textures and procedurals where they can be applied selectively to single image textures or a bunch of procedural nodes. They work great with HDR inputs like sunsky and environment maps and[…]

With v1.2 update, we are introducing a first batch of exciting new utility shaders :  romboTileBlender romboTriplanarMapper romboTextureBlurrer romboThickness All with a single point update ! 😉 These new utilities are under Texture/Utilities folders in your DCC apz of choice. Minor updates for C4D shader structure: romboTransparency is now in the Refract folder (was before in[…]

Rombotools tile blender shader is a powerful stochastic texture synthetizer. It fully preserves texture characteristics and features. Basically it allows to have a texture as input and produce an infinite, non-repeating render-time texture from that. Effectively as soon we start increasing UV repetitions on our texture what we get back is some awful tile artifacts.[…]

This is an advanced utility able to blur both bitmap textures and whole procedural shading graphs. This is useful for visual stuff where you may want to blur accordling to match some renditions you have in mind and/or to improve antialiasing with procedurals nodes.  All we have to do is to put it on the[…]

A thickness shader is a type of shader used to simulate the thickness or volume of an object in a 3D scene. It allows for the creation of more realistic and detailed models by adding depth and dimension to otherwise flat or thin objects. The thickness shader works by calculating the distance between the surface[…]

With latest v1.1 update, we added : a full new shading node, romboReflectRetro full PBR support to the Glints node custom map support for the Glints node automatic fix for bad inverted normals for SSS-RW a new multiple scattering mode to ReflectMultiScatter a re-work of some internal code to be overally faster a new batch[…]

Retroreflection is an optical phenomenon where light scatters back to its source along the inverted incident direction. Materials with retroreflection properties are used for safety garments to help enhance visibility in low-light conditions like roads at night when illuminated by car headlights. Traffic signs and pavement markings also use materials with such properties to ensure[…]

In our quest for an improved diffuse model we already seen a principled implementation and a super smooth lambertian sphere model. We’ll briefly see here a ‘microfacet’ lambertian model that comes with the DiffuseRough shading node. As before we don’t really need to fully understand all of this but a general understading is still better[…]

SkinLayers material is a three layers SSS dipole implementation in the style of the old alSurface material with added features like ‘peach fuzz’ reflections and ad-hoc params to better control overall sss appearance. Works great for anything releated to subsurface scattering and remains super easy and intuitive to use. Here for this Judge Dredd’s caricature[…]

In our journey on diffuse shading we have seen how a diffuse principled implementation better suites modern workflows than the classical Oren-Nayar implementation. The main offender on the Oren-Nayar implementation (rombo DiffuseGeneralized, Arnold Std Material) is that it is based on single scattering and so it leaks energy (diffuse gets too dark with increasing roughness).[…]

Reflections are a complex matter. However we don’t need to fully understand them to be able to use them in a CG workflow, after all reflection slope for example is just a single parameter we may better grasp just looking at the different results we get while tweaking it. But we can still read the[…]

Because Rombo shading nodes are organized by lobes (diffuse, reflect, sss etc.) we need to choose the right one for the work we gonna do. When we have a metalness map for example we have 3 nodes we can choose from : ReflectGeneralized, ReflectMultiScatter and ReflectFlakes.  Being ‘reflect’ nodes the initial setup is of pure[…]

Generally diffuse and specular lobes are layered making use of the Fresnel reflectance at the interface. This simply means that the diffuse lobe is multiplied by 1-Fresnel while the specular lobe is added on top. Practically it means that when Fresnel is at max (at grazing angles) we have only reflections showing up. This ensure[…]

When we generally talk about ‘diffuse’, technically we intend the relationship between surface normals and light direction such that the diffuse model is : N.L. This reads, – N dot L. When we take the dot of two vectors we measure the scalar magnitude between them. Here that means we get the magnitude of the[…]

This shading node does refractions at boundary and then continue the ray into a volumetric medium with single scattering until it hits the back of the surface and it’s finalized into a new direction. This model is generally applicable to materials with low indices of refraction so that their translucent nature implies that a high[…]

This Metallic Paint uber shader is a powerful three layers material able to simulate the complete light transport that happens within the layers. The flakes which are in the middle layer, are multi-scale and BRDF-based (not pattern based) so that at distance they converge to a smooth reflection while at close views they act like[…]

Turns out that most computer graphics conductor materials (metals) don’t fit well with their measured real life counterparts. Looks like microfacet models (any reflection node you ever used..) can’t fully address the appearance of this kind of materials. Microfaceting theory models the appearance of a material at macroscopic level based on surface micro details. Situation[…]

This node basically does multiple scattering refractions. When with romboRefract (or Standard Material) we do engage Scatter in the Refract (transmission) rollout we are doing instead volumetric single scattering. Multiple scattering is slower but more expressive. We can’t really render a resin statuette like this one below with single scattering. Let’s see its main parameters[…]

The SSS Random Walk node is a state-of-the-art subsurface scattering shader. We employ a new sampling strategy for random walks that takes all previouses approaches and put them together for a more effective sampling with reduced render times and great solution quality. Basically what lately did put pathtraced SSS into production is the understanding that[…]

The SSS Dipole shader implements all the relevant dipole models for subsurface scattering available in computer graphics.. namely Standard, Better and Directional dipoles. They are of particular interest because they are better (at matching real life reference materials) than diffusion SSS and way faster than raytraced (random walk) SSS. Let’s see its GUI and main[…]

Microfacet-based normal mapping is an alternative way of faking geometric details without corrupting Monte Carlo based path tracing light transport and it’s available in ReflectMultiScatter and ReflectGeneralized. Theoretically it is well-defined, symmetric and fully energy conserving. On the other side it means that classic normal mapping has none of the properties above resulting in a[…]

Reflection hazying is actually an artifact. It happens due to micro imperfections which widen the actual reflection lobe making reflections appear less vivid and radiant, more milky and less contrasted. Hazing generally is due to poor industrial processes so that metals and other reflective surfaces have an inferior finish quality because of bad drying or[…]

This reflection node is a powerfull shader that supports both geometrical optics and wave optics glints, flakes, brushed patterns and scratches. Unlike in geometric optics, the contributions from different parts of the surface can sum non-linearly due to interference effects, to create the characteristic diffraction effects of wave optics.. ie. those colored patterns we see[…]

The yarn-based material has been updated with: sheen and reflection lobes build-in patterns with HSV controls an all new phase function for better controllable fiber scattering a roughness patch size to better control fiber roughness and specular pattern variations an indirect glossy versus indirect diffuse parameter to better approach some kind of textiles better overall[…]

With rombo Reflect shaders, – we’re introducing microfacet multiple-scattering in two forms: approximated and true random walk multiple scattering. The true multiple scattering is available only with the ReflectMultipleScatter node while the approximated stuff comes with any specular additional lobe attached to the Diffuse nodes; it is an option with the MultipleScatter node itself and[…]

So in the while also Autodesk has added an Adaptive Sampler to the Arnold renderer. It is very different from the one we first demo’ed here last year. The now build-in Arnold adaptive sampler is image based while ours is a multi-dimensional adaptive sampler. What’s the main difference ? A very simple and yet very[…]

While Arnold already uses a stochastic approach for transparency, it comes only as a ‘closure’. Which means that for custom shaders that do not use an all closure approach it is not available, so we had to add one ourselves. Stochastic transparency makes a huge impact on render times where bounces depth is high. Top[…]

Here a video showing the implementation of rombo denoiser with a full Maya GUI and AOVs support. One can simply add a new AOV and select Rombo.Denoiser as an Arnold driver and access the minimal parameters. We support also Maya render region for fast previews of final results.

Here we use a non-local sample-based approach together with feature-based filtering and adaptive sampling. A proof of concept on latest denoising tech plus some creative engineering that makes it working consistently for production. For example, with a little help from the camera and with Arnold in kinda ‘pathtrace’ mode (AA samples 4×4 while all others[…]

Yarn-based Cloth Shader : (aka) micro-fiber based BRDF : micro-fibers orientation returns correct physically-based macro specular highlights, suitable for both close-ups and distant views. Automagic color shifting, normal/bumps simulated with specular roughness for improved detail and consistency. Here we see also fiber fuzziness in action. Procedural weaving pattern support via WIFs (Weaving Information Files) files.[…]

We wanted to try our adaptive sampler on Arnold. We know Arnold is a ‘brute force’ renderer that relies mostly on importance and multiple importance based tecniques without the need for an adaptive sampler as the renderer itself is already faster than most renderer outthere that makes in a way or another use of adaptive[…]

First check you have the following Arnold core : >= 7.2.1.0 (tested on maya 2022, 2023 and 2024 both Win/Linux). Then with Maya we have to edit the Maya.env file for both Windows and Linux installations. MTOA_TEMPLATES_PATH = xxx\rtoa\DCCs\Maya\ae MAYA_CUSTOM_TEMPLATE_PATH = xxx\rtoa\DCCs\Maya\aexml ARNOLD_PLUGIN_PATH = xxx\rtoa\bin Just let the above maya vars point to the correct[…]

First check you have the following Arnold core : >= 7.2.1.0 (we tested rombotools on R25, R26, 2023 and 2024). Then simply set the ARNOLD_PLUGIN_PATH environment variable on Windows. On Windows 10/11 click the win button and start typing ‘env’ you should get an hint like ‘Edit the system environment variables’, clicking on that it[…]

With Houdini the installation is pretty simple and standard for Arnold custom shaders. All we have to do is to set the ARNOLD_PLUGIN_PATH environment variable on both Windows or Linux to rtoa/bin path. Before that however check you have the following Arnold core : >= 7.2.1.0 (tested with Houdini 19.5.xxx). In Windows 10/11 click the[…]

First check you have the following Arnold core : >= 7.2.1.0 (tested on 3dsMax 2022 and 2023). Then simply set the ARNOLD_PLUGIN_PATH environment variable to rtoa/bin path. In Windows 10/11 click the win button and start typing ‘env’ you should get an hint like ‘Edit the system environment variables’, clicking on that it will open ‘System Properties’ ..[…]

First check you have the following Arnold core : >= 7.2.1.0 (tested on Katana 5.0v.1) Then simply set the ARNOLD_PLUGIN_PATH environment variable to rtoa/bin path. In Windows 10/11 click the win button and start typing ‘env’ you should get an hint like ‘Edit the system environment variables’, clicking on that it will open ‘System Properties’ .. at the[…]