How to Colorize Image Based Textures

What if we had the ability to change the color of image based surface textures, directly in Archicad?

Well, in fact we do!

In this tutorial, we'll explore how we can use surface emissions to add an RGB color tint to any texture image. Ideally one that is greyscale. You can download the sample texture here to follow along.

Mission for Colorizing Textures

When selecting finish colors on a project, it can be useful to have the ability to change the visible color of a surface, to exact RBG values (provided by a manufacturer).

This is easy to do in real time rendering software, where we can simply tweak the tint with specific RGBs.

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Inside Archicad, this is also very easy to do for non-image based surfaces, where we simply change the base surface color.

But with image based textures, the process is not quite as easy (although still very achievable!).

Ideal Texture Image Settings

When working with image based surfaces in Archicad, with the intention of adding our own RGB color to them, we want to begin with a greyscale image, ideally with light/white tones ranging to darkened tones in shaded areas.

When we start with a clean white to grey image, it's easier and cleaner to tint color on top. If you started with a red or blue image, it'd be much tougher to work with downstream.

Archicad 3D Environment Settings

There are 3 primary settings in Archicad we will need to pay attention to, when using this method of applying colors to image textures.

1. Surface Settings (Particularly the Emission, and Reflections)
2. Sunlight Settings - Where we control the Sun and Ambient Intensity, Mixing, and Colors
3. 3D Style - Hardware Acceleration Settings (Open GL Settings)
   • Emissions Must be Turned On
   • Highlights (Specular) may be useful
   • Headlight may help darken surfaces, useful to this workflow.

We'll get more into these settings as we explore the colorization process.

Adding Color to Image Textures

We can easily apply a color to an image texture in Archicad, using the often forgotten emission channel in our surface settings. (Basic, not Cinerender)

For Cinerender, we'll have to explore these ideal settings in another blog.

Emission colors in our textures are typically set to pure black, leaving them in an in-active state, or 0 value.

Once we start adjusting emission RGBs away from 0,0,0, to any light shade or color, we start to immediately see this impact on our surface settings in regularly Open GL 3D views.

If you have known RGB value, then plug it in here now, and forget about the intensity slider, it doesn't do much in our openGL scene.

Balancing Light Reflectance

As soon as you turn on the Emission  on your surface, typically you'll need to tone down your Ambient and Diffused Reflection intensity, to balance out and make your surface appear closer to the desired value.

If you have both emissions, and ambient+diffused lights applied to your surface, it will appear washed out.

Limiting Ambient and Diffusion from 0-15 intensity, will make your emission color come through cleaner. Adjusting Shininess and Specular will also make a slight impact on color and shadows.

Limitations: Vertical Projection Viewpoints

If you're working with Elevations, Sections and Interior Elevations, utilizing the Texture Surface Model Display Options, this process of colorizing textures breaks down. You will only see the underlying image in these cases. 

Use a model appearance to include the surface color instead of texture, to get the RGB values set in the Surface Color setting.

Limitations: Physically Based Rendering

Turning on this 3D view experimental feature in your work Environment, will not enable surface emissions.

Limitations: Dark and Night Scenes

Once you add emissions to your surfaces, they will no longer appear dark, even if sunlight and ambient light are not present. Turn off all the lights, and you'll still see your emitting surfaces.

Real-Time Rendering Software Considerations

After exporting to Twinmotion, you'll notice the RGB values set in the colored texture are gone. This is easy to adjust with the color tint settings.

Another surface setting to be aware of, is a slight emission value being applied to our surface. Once you've corrected the RGBs to your defined color, check during a night scene, to see if you're still emitting. If so, zero out your emission intensity (0.03 came through).

Go Deeper, with CONTRABIM!

Last May, we did a 2 hour dedicated live training session on this topic, where we dove into the Surface Settings, Rendering Engine Settings, and Sun and Ambient Light settings. If you want to learn more about how the Archicad OpenGL views work, and interact with surfaces, this training session will break it all down!

Sun and Ambient Colors, Intensities and Mixing.

Specular Colors.

How shadows are impacted with lighting and surface settings.

Thanks for checking out this tutorial blog on Colorizing Image Textures! Download the sample PNG from above, and play with this! Let us know if you have any questions by posting them on the YouTube Watch Page. 

That is it for this lesson! I hope you enjoyed, and we'll see you on another one soon!

John, from CONTRABIM.