Desktop Based: Texture / Material Design Programs
Armor Paint -A Free Powerful Texture Design Program ( A Substance Designer Alternative )
https://armorpaint.org/
Quixel Mixer - A Free Powerful Texture Design Program ( A Substance Designer Alternative )
https://tinyurl.com/quixel-com
JSplacement - Powerful Image / Texture Generator Program
https://windmillart.net/?p=jsplacement
Materialize - A Powerful Realtime Multi-Map Generator Program For 3D Apps
http://www.boundingboxsoftware.com/
Material Maker - Node Based Texture Designing Program
https://rodzilla.itch.io/material-maker
Pixaflux - Node Based Texture Design Program
http://www.pixaflux.com/index.php
GRASS GIS - Image Processing, Maps, Spatial Modelling And Visualization Program
https://grass.osgeo.org/
Aerialod - An Interactive Path Tracing Renderer Program For Height Maps
https://ephtracy.github.io/index.html?page=aerialod
Mandelbulb 3D (MB3D) - Fractal Rendering Program
https://www.mandelbulb.com/2014/mandelbulb-3d-mb3d-fractal-rendering-software/
Multiview Environment - An End-To-End Pipeline For Image-Based Geometry Reconstruction Program