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[…]

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[…]

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[…]

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[…]

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[…]

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[…]