gimp beginner here, drawing terrain heightmap in gimp/krita, need help regarding gradient/color blending tools.

1) First of all, gimp and krita both supports 16bit .png or .raw for unreal engine export?
2) If possible describe solution in both gimp and krita, in which tool it will be easier to draw heightmap? Also give me youtube tutorial links if necessary.

3) I have this image. But this can't be used as proper heightmap because there is no slope, the color change is sudden.
https://imgur.com/a/kqWxQ [image too wide to upload here]
I want gradual color shift from white channel to black channel, what tool I need to use. Some tools gonna blur the image badly so white channel and black channel will lose contrast, which is problematic for height. Whats the best tool to gradual color shift without lose highest or lowest value of white channel in the map?
Let me explain what I really want, I want to draw basically white and black and maybe 2 or 3 shades of grey ( ) in the heightmap, but I want a gimp tool to blend the color in the edges of each shades, the the transmission will be smooth [drawing slope in a terrain]. In a sense I want to make clouds[mountain and slope].

4) How can I make sure I am painting in a gradient paint brush? So my paint is gradually increasing or decreasing its white channel value? Like this
This brush is gradually changing its shade, I want some thing like that when I draw.

5) In case you are still wondering what I want to achieve, just google heightmap crater, I want mountainous and desert region in the same map. Thanks in advance.

If blurring, to smooth brushstrokes, gives contrast reduction then you can restore black/white levels by using the contrast adjustment or the levels filter tools.

For a gradient brush, value varying by distance, you can modify the characteristics of one of the standard 'simple' brushes, like this: https://imgur.com/CPIqFhE

Then you can paint height maps: https://imgur.com/mnIBbs3
A bit of blurring will make that smoother then a level adjustment would restore it to peak black-white transition.

I was going to do a volcano with a caldera lake and an overflow drainage gulley but I don't feel confident about my artistic abilities.

ahabgreybeard wrote:If blurring, to smooth brushstrokes, gives contrast reduction then you can restore black/white levels by using the contrast adjustment or the levels filter tools.

For a gradient brush, value varying by distance, you can modify the characteristics of one of the standard 'simple' brushes, like this: https://imgur.com/CPIqFhE

Then you can paint height maps: https://imgur.com/mnIBbs3
A bit of blurring will make that smoother then a level adjustment would restore it to peak black-white transition.

I was going to do a volcano with a caldera lake and an overflow drainage gulley but I don't feel confident about my artistic abilities.

thanks do you have any other tip for me? what I need is tutorials, specially about airbrushes... where can I find custom brushes/ airbrush for krita

This is a subject I know some things about. Actually it is a massive subject and there are so many ways to explore it. So many ways, in fact, I don't know where to start.

First of all, if you want to use Gimp, then you will need the newer 2.10 version to get 16 bits. 8 bits will limit the range to 256 values, and that may work in some instances, but for very large areas then you will likely want more than that.

"Let me explain what I really want, I want to draw basically white and black and maybe 2 or 3 shades of grey ( ) in the heightmap, but I want a gimp tool to blend the color in the edges of each shades, the the transmission will be smooth [drawing slope in a terrain]. In a sense I want to make clouds[mountain and slope]."

You can posterize a black and white image (with the G'mic Posterize filter or in Gimp with Colors->Posterize) to 5 colors, then smooth it with a Gausian blur or use a smudge or blur tool to make the transitions smoother.

You can also use the color levels to set the minimum/maximum height or color range.

Krita has an awesome feature of filter layers which are non-destructive. Personally, I would draw a heightmap in Krita in black and white with a wacom stylus, where the harder I press, the darker (or lighter) the gray, with a Phong bumpmap filter layer, so I could see better high and low the elevations. The end result would be a grayscale heightmap (with the bump map filter layer turned off).

If you are into hillshading, Gimp has a pretty nice bumpmap filter itself. Gradient mapping is also something to look into.

Really, the subject is so vast that an entire book could be written about it.

If I have some time later I can post some examples of what I mean and maybe find out If I understand better what your are asking

I don't know anything about airbrushes and I rarely get beyond the pencil and crayon stage when I use image applications for 'artwork'.

YouTube has lots of krita tutorials that may be of help to you. There are also written tutorials in various places. Deviantart.com has many brush sets for Krita, all made by experienced users. Just do a Google search for 'krita brushes', 'krita tutorial' and 'krita documentation'. You will find them.