Random Hue Shift of Image Textures?

Started by bcgreen24, July 25, 2022, 10:38:44 PM

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bcgreen24

Hi, folks--- I looked at few old posts about the topic of randomly tinting objects in a population (randomly adjusting the hue so that you get a range of colors from green to yellow to orange for trees, for example)--- and the posts made this seem difficult and only possible with crazy workarounds.

However--- I could have sworn I saw a post at some time in the last year or two that had a tutorial for a simple way to accomplish this.  Does this ring a bell with anyone?

Thanks!
Bryan

Dune

#1
If it's just a hue variation over a population, it's very easy; in the color tab of a population you can add fractals or image maps, or other masking (altitude, slope, etc, by distribution shader).
If you need to change the color completely over a population, say from green to orange randomly a simple addition wouldn't work (an orange fractal would just turn the greens into drab grey-brown), but there's an easy way within the object of that pop.
1. add a surface shader below the default shader and mask it by whatever mask you need, but pulled through a transform shader set to world position.
2. add a (blue node) adjust saturation node to the color input of that surface shader, and pull a line from the default shader into the blue node. Add a (blue node) constant set to zero. This turns original color into greys. If greys are too dark, just set color to 5 or so instead of default.
3. add a color adjust shader to the child of the surface shader and set different color in gamma. This will change the unmasked part into the new color.
4. beware that any translucency is lost by the surface shader, so you might need to add a Lambert shader to the child as well. Check 'use existing color' and the translucency needed.
5. might be that reflectivity is alo lost (I'm not sure), so you might need to add a reflectivity shader in the child line as well (set to non-RT).

This is one way. I hope this will work (easily) for you.

Kevin Kipper

Here's a link to the wiki tutorial on tinting populations:
https://planetside.co.uk/wiki/index.php?title=Population_Colour_Tinting_Techniques

Also, in video #19 of the Terragen for VFX series we cover the tinting process in detail:
https://www.youtube.com/watch?v=7MbBJMMl2QA