Mandelbulb3d has several ways to render 3d fractals. One of them, dIFS, has the ability to make use of height maps.
This tutorial focuses on creating custom height maps.
This is not news worthy - MB3D artists have long made use of this technique. Recently my friend Jorge - batjorge - has posted a tutorial on using dIFS with a height map - the HeightMapIFS and the amazingIFS formula. The tutorial is meant to easily generate the classic bulb shape and it achieves this admirably. The height map in Jorge's guide is a uniform, gray image. This results in a clean and texture-free bulb form. But what happens if a more complex height map is used?
This tutorial will walk you through creating a quality custom height map and applying it in a MB3D dIFS render.
This image - New Heights - uses a custom height map.