How to Assemble a Complete Specular Map in Your Farming Simulator Mod

By Jason van Gumster, Christian Ammann

You can add detail to your Farming Simulator mod with a complete specular map. You may have painted or baked textures for your specular, ambient occlusion, and dirt maps. These textures are saved in separate images, with names something like the following:

  • myFantasticMod_specular.png

  • myFantasticMod_ao.png

  • myFantasticMod_dirt.png

Unfortunately, GIANTS Engine can’t use these images directly. You must combine them into a single image, specifically the specular map image. To do it, you have to use a neat trick that takes advantage of the fact that all three images are grayscale.

In fact, stop thinking of them as images. Instead, think of them as grayscale representations of information. The specular map is a grayscale representation of shininess, the AO map represents ambient lighting effects, and the dirt map, most obviously, represents dirt buildup.

Most digital images consist of three color channels: red, green, and blue. You can think of each of those channels as grayscale representations of how much each of those colors influence the overall image. What if you didn’t use those channels to represent colors? What if you used them to represent information like shininess, light, and dirt? You would have a way to combine three maps into a single image.

The image itself may look quite strange, but this use of the red, green, and blue channels is exactly what GIANTS Engine expects you to do for the specular map image. You need to edit your specular image, mapping data to each color channel as the following table shows:

Color Channel Texture Map
Red Roughness (specular)
Green Ambient occlusion
Blue Dirt

The process you use to assign each texture to its own channel is pretty straightforward in Photoshop. Use the following steps:

  1. Open your specular image (for example, myFantasticMod_specular.png) in Photoshop.

  2. In the Channels window, select the Green and Blue channels.

    The overall image should turn a slightly green-blue color, and the Red channel should appear to be disabled.

  3. On your image, select all (Ctrl+A).

  4. Fill this selection with black (Edit→Fill).

    You should notice that the Green and Blue channels are black whereas your specular texture is still on the Red channel.

  5. Open your ambient occlusion image (for example, myFantasticMod_ao.png).

  6. Select all in your AO image (Ctrl+A) and copy it to the clipboard (Ctrl+C).

  7. Switch back to your specular image and select only the Green channel in the Channels window.

  8. Paste your AO texture (Ctrl+V).

    You should now be able to cycle through the channels and notice that your specular data is on Red, AO data is on Green, and the Blue channel is still blank.

  9. Use the same process in Steps 5–8, but for your dirt map, and paste that data into the Blue channel.

  10. Save your specular image (for example, myFantasticMod_specular.png) and you’re good to go.

When GIANTS Editor loads your specular image, it automatically knows how to handle each of the channels, so there’s no additional work for you to do there. Pretty clever stuff, huh?