Render Engine review: Maxwell Render

Written by Luis Cruz on Monday, 15 August 2011. Posted in Academic Portfolio

Advanced Image Synthesis | CS 7490

Maxwell Render

This project for the Advanced Image Synthesis was the analysis and review of a Render Engine. I chose Maxwell Render because its realism. Maxwell render is a rendering engine based on the mathematical equations of light transport, meaning that lights, cameras, materials and emitters are derived from physically accurate models.

This render engine was released in 2004, and it was implemented on a Global Illumination algorithm based on a Metropolis Light Transport variation. Maxwell render is described as an "unbiased rendering" meaning that does not apply tricks to calculate the solutions.

Given the physical-model nature of this render engine, we get almost any feature from a sophisticated renderer with minimal tweaking such as Global Illumination, Radiosity, Final Gathering, Caustics, Reflections, Refractions, Ambient Occlusion, shadows among others.

cs7490 Maxwell Emitters cs7490 maxwell cam thumbThere are two important differences with other render engines: Camera and Lights. The camera in Maxwell is based on a real SLR camera, meaning that you have access to Film ISO, Shutter Speed, F-stop, Diaphragm, etc, just like if you were working on a real camera (See image). Maxwell does not have "abstracts" lights such as other engines, instead it uses any geometry as an emitter and they behave like real lights meaning that you can tweak Temperature, Power (watts), Luminance and others (See image). One very useful feature is Multilight, by using this option the user can tweak the Lights while rendering and see the results almost instantly without the need to re-render everytime you tweak the lights; on the Render UI image above, you can see the Multilight panel where each slider corresponds to the ISO level, Shutter, Environment and each Emitter material that is included in the scene.

Model/Scene Support

The standalone application which is Maxwell Studio is a full featured scene editor with a full 3D environment that can accept any 3D scene in the following formats: OBJ, STL, LWO, PLY, XC2, DXF, 3DS, FBX, Collada, MXS.

Maxwell is not only a standalone application but also has plug-ins for multiple 3D and CAD applications such as: Maya, 3DS Max, Cinema4D, Softimage, Modo, Lightwave and more. These plug-ins highly integrates with the host application; therefore allowing to render almost any type of surface that can be created in the host application. Here is the complete feature list.

Maxwell does not use any API or Shading Language. Instead it comes with a robust Material Editor to create Physical correct materials. It supports stacked layers, BSDF materials, Subsurface Scattering, Fresnel simulation, Spectral dispersion, anisotropy, Displacement, Bump and Normal mapping among other features.

Sample Scene

cs7490 Maxwell sample render 5min cs7490 Maxwell sample render 24min They include a sample scene for Maya that can be downloaded here. The 3D models do not have the materials applied, so I created some materials by using their own public library and also following the Maxwell Maya tutorial. I tried to apply different type of materials such as glass, plastic, porcelain and image textures in order to observe the capabilities of this renderer. Be aware that this scene does not have any lighting setup, everything is done by Image Based Lighting using an HDR file (you can see it in the background of the render). This IBL setup was easily applied by using the Maxwell Render setting in the Maya Plug-in. Other options for environment lighting include Physical Sky and Sky Dome. As for the render settings, be aware that nothing was tweaked besides the IBL setup. I made two renders; one that ran for 24 minutes and the other that ran for 5 minutes. Take a look at the pictures to see the difference. Note: These renders are straight out from Maxwell, there is no compositing/editing.

Maxwell render Sample 24 minutes

cs7490 maxwell render sample 24m

Complex Scene

For a more complex scene I have chosen a Sports Car 3D model based in a Digital Tutors tutorial. All materials are Maxwell materials. Everything was done in Autodesk Maya 2010, the 3D model has a combination of Polygons and Subdivisions. The illumination is entirely in IBL (HDR file) and I  added 3 light emitters (the 3 bulbs on the floor). The scene was easy to setup, but chosen good materials took some trial and error.

Maxwell BSDF There are 18 materials applied in this scene, and most of them are BSDF materials with textures, coating or multi-layer materials. The car paint if probably the most elaborated material in this scene, it has 3 BSDF layers including 1 coating layer; I have included a screenshot of all the BSDF panels for only 1 of the layer materials for the car paint. You can create your own materials, or also within the Host application (in this case Maya) you can browse for local material galleries or import materials from the Maxwell community. I rendered two scenes. The first one was let ran for 25 minutes, and the second one which is a night scene was let ran for 14 minutes. Note: These renders are straight out from Maxwell, there is no compositing/editing.

Maxwell Render 25 minutes

cs7490 maxwell car 25m


Maxwell Render 14 minutes

cs7490 maxwell car 14m


Conclusion

I have used the Maya Software Render and Mental Ray, and I can say that Maxwell is an excellent render and it is very easy to use. Here I list the Pros and Cons:

Pros:

  • Easy! Next-Limit advertises this product as "easy as taking a photo", and they are not lying. If you have applied the right materials and lights you can render with no tweaking or being an expert in render concepts such as Global Illumination, Photon Maps, Final Gathering, Filters, etc.
  • Not sure about the lighting setup? No problem, Maxwell features something they call Multilight. Multilight allow the user to tweak and Light emitter, ISO, and Shutter while rendering; therefore, you can change the color and intensity individually. Refer to the screenshot at the beginning of this review and you will see the Multilight panel.
  • Resources. There is good documentation, tutorials and more importantly, there is a community where you can download materials; at the moment of writing this review there are 3,794 materials.
  • Platform: Standalone and plug-ins available for almost every professional 3D and CAD application.
  • Quality. Very photo-realistic results.

Cons:

  • Slow. Although you can start getting very good results within a short time, it is definitely slower than other renderers. For still images is excellent, but for animation, you may want to start looking for other render engines such as Renderman or MentalRay.

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About the Author

Luis Cruz

I am pursuing my MS in Computer Science at Georgia Institute of Technology (GaTech) with emphasis in Computer Graphics. I received by BS in Computer Science at GaTech in 2009 with specialization in Software Engineering and Computer Graphics.

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