Chaos in Harmony

A Stroll Through the Blinding Lights of Cyber City

Rendered with NeoTracer, by Kshitij and Arihant.

Story

Our scene showcases a glimpse of a cyberpunk-inspired city, populated with high-rise buildings, with neon lights breathing life into it. Our city lies amidst dense fog, which adds to the eerie vibe of our scene. The harmonious combination of the neon signs and buildings while showering in the ominous, chaotic fog looming over the city encapsulates the theme of this rendering competition. A person residing within the scene might have their visual sensors chaotically overstimulated, but couldn't get enough of the eye-candy which our scene has to offer.
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Scene

Allowed adding texture details on meshes without additional complication

Rough Dielectric

Provided photorealism by adding frosting to glass dielectric as shown below

Area Lights

Not only did it light up the scene in a more photorealistic fashion, but also reduced the overall noise as shown

Improved Area Lights

Simply changing the PDF sampling schema to subtended cone sampling reduced the noise further

MIS Path Tracer

We show our results from a test case by Eric Veach. This demonstrates improved sampling along the areal emissions

Homogeneous Fog Tracer

Respecting our overall cyberpunk theme, we added fog to our scene with a volume tracer that allows for handling homogeneous participating media

Image Denoising

Using Open Image Denoise Library (OIDN) from Intel, we reduce the noise further from our scene

Postprocessing

Adding bloom at the end makes light emissions and reflections even more realistic

Statistics

Key metrics and performance data for the renderer.

Render Time

4 hours 17 minutes

Light Sources

6

Samples per Pixel

512

Resolution

2565x1440 pixels

Hardware

Ryzen 7 7840HS 16GB RAM

Meshes

2.79 Million

Assets

External assets and resources used to create the scenes.

Enormous26

Gumroad

Neon lights

CGTrader

More neon lights

Kitbash3D

Obtained tall building assets

CGTrader

Urban trash set

Polyhaven

Ground asphalt

Challenges

One of the key challeges we faced was to get volume path tracing for homogeneous media to work. As opposed to PBRT's implementation of attaching medium property to the ray, we took an instance-centric approach where our scene lies in a cube having medium property associated with it. We explicitly track and maintain number of bounces in the cube instance to determine entry and exit from the media. Since we do not use localized homogeneous media, this hack suffices for our use case.
We also faced minor issues with getting improved area light sampling to work alongside MIS path tracer. We had to ensure that PDFs were computed and returned in the right domain, specifically conversions between spatial and angular domains.

Credits

We would like to thank the course instructors for equipping us with the knowledge to write out a ray tracer from scratch. We would also like to thank our tutors for their invaluable support and assisting us through the assignments and the rendering competition. Lastly, we provide references for the links that were used as additional resources for scene creation:

PBRT

Additional literature

Scratchapixel

Additional literature

CG1 2024

Lecture notes

Microfacet

Microfacet Models

For dielectric BSDFs

Akalin

Sphere sampling

For improved area light sampling

RIS

RIS 2024

For MIS path tracer

VolPT

For volume path tracing