Quick Guide: My Texture Workflow in Houdini Karma
Because a few people asked how I set up my textures, I thought I’d write this quick guide. The setup in Karma is fairly simple, but there are two or three small things to watch out for, plus a few useful tips. In theory, this workflow doesn’t only apply to Houdini Karma but can also be used in most node-based setups.
If you want to try this workflow using my own textures, you can find them here.
First of all, we need to create a Karma material.
After that we need a MtlX Texcoord, followed by a MtlX Add node which is responsible for our offset value. Especially when working with seamless textures, this is super helpful to position them perfectly. Then a MtlX Rotate 2D to rotate the texture, and finally a MtlX Multiply to scale the texture on the X and Y axis. (I usually right click the X value, copy parameter, and paste a relative reference into the Y field to keep the aspect ratio.)
Then, depending on the setup, we need one or two MtlX Tiled Image nodes, one for the base color and one for the AO (ambient occlusion) maps. I multiply the two values together to combine the base color with the AO shading information, which helps to add depth and shadow detail to the texture.
After the AO channel, I add a ramp to control and remap the AO values, which gives more artistic control over how the shadow information is blended. This also allows me to control the color of the shadows. For example, with wood textures I often use a dark brown instead of pure black, since black can look a bit too harsh.
After the base color, I add a Color Correct node to adjust things like hue, saturation, and brightness. This is useful for making textures look brighter, darker, or more vibrant when needed. Sometimes I also feed the base color into the subsurface color input, especially for porcelain and sometimes for wood materials, since they can have subtle subsurface scattering that lets light softly pass through the surface, creating a warmer and more natural look.
Then it’s time to create a Null. My textures are numbered at the beginning of the file name (01_, 02_, 03_, etc.), while the rest of the name stays the same. This allows me to use a string parameter to switch texture sets quickly with one click, which is super handy for quickly comparing different textures without creating new materials.
Simply go to the top right of the Null node, click Edit Parameter Interface, drag a String parameter over, and click Apply.
You can then simply type the number into the empty field on the Null. Right click, copy the parameter, and in each MtlX Tiled Image node replace the number using Paste Relative Reference. Do this for all MtlX Tiled Image nodes, including base color, roughness, normal maps, etc. Once everything is set up, you can quickly switch between texture sets. Your texture path can then look like this:
$JOB/textures/wood/01/01_wood_basecolor.jpg
becomes
$JOB/textures/wood/chs("../reference/newparameter")/chs("../reference/newparameter")_wood_basecolor.jpg
The roughness channel is actually pretty self-explanatory. I usually add a Color Correct node after it and adjust the contrast or gamma values to make the surface look rougher or more shiny. Alternatively, you could also place a ramp behind it and control the roughness values that way.
Next come the normal maps, where the magic really starts. In Karma this is very important! Set the signature of the MtlX Tiled Image node to Vector4.
Besides the normal map, I also use a bump map in about 95% of cases. I remap the base color image to black and white, then add a MtlX Bump node and mix this value with my normal map. However, the mix between the normal map and the bump map is usually very subtle. Often 5–10% is enough, otherwise the bump can start affecting the roughness too much. This adds extra micro-detail and looks much more realistic than using only a normal map.
And last but not least, the displacement map. This is pretty straightforward. What I usually like to do is add a MtlX Range node behind it and remap the values to -1 to 1. Displacement shaders usually work best when values are centered around zero, since this allows for both inward and outward displacement. This results in sharper and more balanced surface details. Using a 0–1 range can make the surface look inflated because it only pushes the geometry outward.
I hope this post helps you a little. If you have any questions, feel free to write to me on Instagram or via email. And if you have a better or more efficient workflow, or better settings, I would also love to hear about it. I’m always open to learning new things. <3
If you want to try this workflow using my own textures, you can find them here.