Rendering a Volumetric Image

Question

So today I decided to try making a volumetric texture. (I found a mod for Kerbal Space Program that adds custom volumetrics, and I wanted to try making something.) If you're unaware, a volumetric texture is basically 3D voxel data that's been sliced up and placed onto a 2D texture. Here's an image to demonstrate:

(Green is Y, red is X, and blue is Z. Also, it's scaled down. The original image was 4096*4096.)

The tiling system starts from the bottom left corner and goes up. Once it reaches 16 images, it loops back down, moves one space to the right, and starts again. This repeats until there are 256 tiles.

Here's the question: I have the individual images rendered already, but I don't know how to tile them (other than painstakingly stitching 256 images together.) Do any of you know how?

Here's the images I've rendered, in case you'd like to use them. They're not perfect, but it's a start.

Answer 1

Non Blender

This task would be faster to solve out of Blender ... some online generator or by ffmpeg (if installed) via Terminal with the command below (here is step-by-step tutorial) ... it works for me - fast almost one click (copy-paste) solution.

ffmpeg -i %04d.png -filter_complex tile=16x16 output.png

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Blender

If you incist to use Blender, here is one way.
Volumetric texture from image sequence can be achieved by UDIM Texture like answered here. UDIM generates sprite sheet 10 x n grid. For volumetric texture is each tile vector translated into a slope at Z axis.

– Shader
For your need you would have to change the way of translation from 10 x n to 16 x 16.
That I'm going to skip for now.

– Geometry Nodes
For the same purpose you can follow a quellenform's answer, that generates UV translation of UDIM's grid into custom sprite sheet from geometry. The only one thing I changed in his node-tree is instancer (see node-tree) and Scale Instancer node to 0.1 ...

Custom UV than looks like this ...