Trailing the lights


I got the inspiration for this scene from various sources. One such inspiration is from my trekking to Kyangin Gumba, Langtang . Upon witnessing the mountains up close, it's no wonder it would be a good idea to include it for the render. Only having mountains isn't enough to make the scene look beautiful. You would need to create some settings of life around it. The pastures in the mountain hills add greenery to the scene creating an amazing contrast. It's visible in the photograph above.

This scene from the movie "Brave" has a simple sketch to it, but it looks majestic when viewed from a certain angle, giving the impression of being able to communicate with the void. But that alone wouldn't do anything. Enter Lights. I wanted to add

Enter Lights. I wanted to add Aurora Borealis but it was a lot of work to do, therefore I went for the alternate route. Creating comet trails.

Unique Features

It's heartbreaking to mention that everything here is a Lambertian material. An ideal world. Another limitation includes exclusion of normal mapping. However, there are some pretty niche features worthy of highlighting.



Crystal Ball

A colored gas with isotropic material suspended above a colored glass to create a crystal ball and halo effect. Details in rt/primmod/volume.h



Comet trails

Created using motion blur and moving glass as well as moving gas. The gas glows to emit a light effect blending two different moving spheres. The spheres are carefully placed to create a notion of a comet shower. Details in rt/effects/motionblur.h




Every leaf blade in the scene is a billboard that uses image texture on a plane to create an illusion of 3D shape. Details in rt/primmod/transparent.h



Environment map

It was quite difficult for me to create a star as a light source. Therefore I went with an environment map to create the night sky that uses a skybox and FlatMaterial. rt/solids/worldbox.h and rt/coordmappers/environment.h

Common Features

Bounding Volume Hierarchy

With 58,385 faces, the scene would take very long to render a scene with 11 area lights. Therefore, BVH speeds up rendering significantly. Details in rt/groups/quickbvh.h.


Given the complexity of the scene, it would be impossible to make it with 58k faces only. Therefore, smoothing creates the illusion of a smooth scene, which overcomes the limitation of having low polygon within the scene. Details in rt/solids/striangle.h

Depth of Field

Adding depth enriches a 2D image, therefore there is implementation of depth of field. The details can be found in rt/effects/motionblur.h

About Scene

The entire scene takes around 18 minutes to render the thumbnail. The complete scene takes almost 4 hours to render. In both of the cases, the sampling is set to 200 samples.

This scene highlights the depth of field. The original render has a depth of field but negligible because of very small apperture.

You can see the scene in its making.


Thank you everyone for your assistance and support.