Website powered by

Multi HDRI Projection

Purpose

Projecting HDRI on a Lidar or a Tracking Geometry for accurate reflection is commonly used in the VFX pipeline. Let's say we have a huge scene for rendering, and we have multiple HDRIs of the same location for projection. But projecting single HDRI for such a scene is sometimes not sufficient as the HDRI starts to pixelate over a certain distance. In such cases, using multiple HDRIs for projection would be a great solution to create a Master setup. I have prepared a simple setup for a multi HDRI projection.


Db7ebe121a271b9af16860f3f05e2baa

For the representation purpose, I have used 3 colors as a projection on the ground. Here we are getting Yellow and Cyan colors where 2 projections are blending with each other.


7d26a2d6b7da7e81a57a733cd422b474

You will be replacing lidar_placeholder with the scene Lidar Geometry and assigning the same shader. I have added some attributes in place3dTexture nodes to control the projection mask.


C9b4b60251f4d526d95da4df2c0dcf91

So the logic here is, we need a mask to cut off one HDRI to a certain distance so it will not pixelate as well as won't completely overlap with other HDRIs. I have used some math nodes to generate the mask which will follow the place3dTexture's placement interactively.


730c1177cdb4669e32cf5bcc3994df83

Based on per shot requirement, we can transform entire setup just by transforming the main parent "HDRI_PROJECTION" group.


879598dd5674eb4d0eeb076e493de60a

place3dTexture node Attributes:


Translate XYZ - Default attributes to control the position of the projection HDRI.

Rotate Y - Default attribute to rotate the projection HDRI. I have removed Rotate X and Z which you can bring back from Channel Control.

Min Radius Falloff - The distance at which mask falloff fades in.

Max Radius Falloff - The distance at which mask falloff fades out.

Mask Shape - Box and Sphere are 2 options to select the shape of the mask.

Mask Rotate Y - Y-axis rotation of the mask, not the place3dTexture rotation.


62e4950272de6add2039fdeb87629e12

I have set up the shader for 3 HDRIs which you can plug in your existing projection setup.

Arnold 5.0+ - Download
Arnold 5.3+ - Download (All Arnold Nodes)