How to color 3D Mandelbrot height map images using DE colors without "spilling"

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Offline Duncan C

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« on: February 24, 2020, 01:08:33 AM »
I've been able to do 3D height maps of Mandelbrot and Julia set images with my app, FractalWorks, for a long time. I find the best results using Distance Estimate data for the height values.

I also often use DE data to color "near neighbors" of the Mandelbrot set. (The thin "tendrils" that connect different regions of Mandelbrot points together.)

However, when I do that, the DE coloring of the near neighbors tends to bleed onto the sides of the 3D slopes, making the 3D shape look odd.

Below is an example image of mine showing the problem:

That's my attempt to duplicate an image from another thread here at Fractal Forums:

https://fractalforums.org/fractal-image-gallery/18/mandelbrot-height-map/1866

That image does what I'd like to do, without the color from the top of the 3D image bleeding onto the sides of the 3D "hill"

How do other programs that do 3D height maps and color "near neighbors" of the set so that only the peak elevations of the 3D plots are colored differently, and that color doesn't bleed onto the slopes?

Linkback: https://fractalforums.org/programming/11/how-to-color-3d-mandelbrot-height-map-images-using-de-colors-without-spilling/3335/

Offline C0ryMcG

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« Reply #1 on: February 24, 2020, 04:37:54 AM »
I haven't attempted this myself, but from looking at your image, and the more 'ideal' image you linked to, my first guess would be to try to scale the resulting heights, based on the color. Off the top of my head, I'd try 1-(1-c)^2 where C represents DE color ranging from [0-1]. This might make the tendrils look more like they belong on the shape.
You wouldn't want to remove the verticality of the fine details completely, see, but they're obviously having too much of an impact on the shape, aesthetically.