what is bella?

Bella is a state of the art spectral renderer, built from the ground up to achieve unmatched realism.

By adhering to a physics-based approach, it not only produces truly photographic images, but does so with a predictability that both simplifies use, and enhances productivity.

Through its flexible node system, and its intuitive physically-based material and camera models, Bella seeks to help you unlock your true potential as a digital artist & photographer.

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Spectral Rendering

Bella works in spectral space, allowing effects such as BSDF wavelength dependency, diffraction, or atmosphere to be modeled far more accurately than in color space.

Complex Caustics

Bella is capable of solving caustics through specular surfaces, for accurate rendering of swimming-pool caustics, caustics seen through windows, emitters enclosed in glass, etc.

Customer-first Licensing

Bella's licensing is uncommonly -- and deliberately -- customer-centric. Both licenses (seat and node) are floating, permanent, and designed to be trouble-free.

Layered Materials

Bella's materials provide real layers with inner subsurface scattering. Light interacts physically with the substrate, the layer, and thin films, in a very efficient way.

Thin Film

The Thin Film node, which may be applied to a material layer or substrate, simulates a nanometer-scale film, providing physically-accurate iridescence.

Nested Dielectrics

The nested priority feature in Bella materials allows correct and convenient rendering of intersecting dielectric (i.e. glass, liquid) volumes.

Complex IOR

The Complex Material provides a simple way of using measured spectral refractive index data. Use of external IOR files or data is optional.

PBR & Smart Materials

Bella's Smart Materials provide a quick and easy way to create materials with just a few simple parameters. Its PBR, Principled, and Uber materials allow use of PBR textures which ranges from a single-click, to full customization.


Like everything else, textures in Bella are node-based, allowing an output from one texture to be used as an input to another.

Pervasive Instancing

Bella provides extensive support for instancing -- indeed, everything that can be seen in a Bella scene is inherently an instance.

Physical Sky & Sun

Bella's physical sun and sky model may be controlled by date/time and location, or by specifying direction explicitly.

Procedural Lights

Bella provides several types of built-in procedural lights, including point, spot, area, and directional.

Thin & Thick Lens

In addition to its standard thin lens, Bella also provides a unique thick lens, which simulates complex effects like chromatic aberration.

Sensor Bloom

The Bella camera supports simulation of sensor bloom: when a pixel is saturated beyond its capacity, it bleeds energy into adjacent pixels.


When light passes through the aperture of a diaphragm or grating filter, it diffracts, producing characteristic light patterns in the sensor.

Cooperative & Resume

Cooperative rendering allows you to render in several computers and merge result. This also allows resuming of a render after it has been stopped.

Intel Denoiser

Bella incorporates Intel's excellentOpen Image Denoise library, for both IPR and production rendering.

Industry Standards

Bella makes use of several industry-standard libraries, for seamless compatibility with a wide range of formats and standards.

Render Passes

In addition to production beauty pass, Bella also provides passes such as alpha, shadow, material & object ID, normal, etc.

Geometry Import

The Bella GUI supports import of several common formats including OBJ, FBX, DAE, 3DS, and STL.

Scene Transport

Through its .BSZ format, Bella provides for easy single-file transport of scenes and their dependencies.
Continue reading "Features"



Thanks to ThomasAn. of Rayflectar Graphics for allowing us to include these images.



Bella has been created to be the type of software that we, ourselves, prefer to use, not only in how the software itself is designed, but also in how it is offered as a product, and in how it is licensed.


We believe in offering a clear and simple product -- therefore, the only Bella offerings are the seat license, which includes all Bella software and plugins, and the node license (reduced cost, for CLI rendering only), neither of which is locked to any particular machine or operating system.


We do not believe in forcing our honest customers to pay the price (in terms of the inconvenience, and inevitable failure of draconian licensing schemes) to protect Bella from unauthorized use -- therefore, the Bella license is implemented as a simple text file.


We believe strongly in respecting your right to privacy -- therefore, Bella neither requires contacting any remote server to validate or register a license, nor does the software attempt to establish any remote connections, at all, during use.

About Us

Bella is developed by Diffuse Logic, a Barcelona-based software company with decades of cumulative experience in the fields of physical simulation and rendering, as well as user-interface design and plugin integration.

Óscar Cano & Albert Martinez

Responsible for our core rendering tech, Óscar and Albert are experts in modeling the complex optical physics involved in simulating the behavior of light, and pioneers in the practical implementation of physically-based rendering..

Jeremy Hill

Jeremy is responsible for our APIs, for developing our applications and plugins, and for creating the systems we use for building and deploying our software.