An SOPack - Overlay Essentials Tutorial

                   

This tutorial covers the essentials of using bitmap pictures as terrain textures in Terragen.  It will also show you how to make the visually stunning image seen at left.  ;-)

Before we continue, make sure  SOPack is installed.

Next, save the three images listed below  into a single directory.  The images must be saved as bitmaps. 

To save the image as .bmp using Internet Explorer,  view the image, then right click and select "Save Picture As...".  After selecting your directory, select "Save as type:  Bitmap (*.bmp)" at the bottom and save.  Do this for all 3 images.

Lastly, download and unzip the World File into the same directory.

 

Images:
Alien Mask - This is a hand drawn grayscale image that will be used to define the area where the dead grass will appear.
Green Lawn - OK, now it gets exciting! - This is a high-res picture of my lawn.  Notice that it's square - this is important.
Dead Lawn - A high-res picture of a dead spot in my lawn.

World File:
Alien World File - This is the Terragen World File you will use to create the image.

Just a reminder - Please make sure the images are converted to .bmp form.  Now, lets begin.

Step 1:  World file and Terrain

Load the world file into Terragen.  That's all.  There is no terrain file to load because we are using a flat terrain.

One nice thing about overlays is that Terragen will render the full detail of your texture regardless of terrain size.  This means that for a flat terrain, size doesn't matter, so the default 257x257 is fine.

 

Step 2:  Understanding and Applying Masks

A mask is a square grayscale image that tells SO Pack where to put an overlay.  If you don't use a mask, the texture you specify will be applied over the entire surface layer. 

The parts of the mask that are white are where the texture will be applied.  The parts that are black are where the texture will be ignored and the underlying surface layer will show through.  The parts that are gray are where the texture will be semi-transparent. 

Look at the hand-drawn mask on the left.  The lines are solid white inside and slightly gray on the edges.  Also, notice the three streaks coming off of the bottom circle.  Watch what happens to these gray areas when we apply this mask.

Now, lets load the mask and see what happens.  Notice the surface map: there are only 2 Surface Layers - Green Grass and Dead Grass.  Dead Grass is lower in the list which means it will appear on top of Green Grass.  We will apply the mask to the Dead Grass surface layer. 

The white lines are where dead grass will be seen.
The black parts are where green grass shows through from underneath.

To apply the mask, go into the Surface Layer properties for Dead Grass by double clicking it.  Then click on the Advanced Distribution tab.  You will notice that there are 2 separate "Tex" buttons:  one on the top under Base Surface and one at the bottom under Advanced Distribution.  This is important:

Only use the "Tex" button under Advanced Distribution (bottom) for masks.
Only use the "Tex" button under Base Surface (top) for textures.

Since we are applying a mask, we click the bottom "Tex" button.  This brings up the SOPack window.  To add our mask, we click "+".  Notice that there are four options.  We want to select "SO Image Overlay (Surface Distrib. Version)".


 

Surface Distribution Version RGB Texture Version Contour Overlay Strata
Used for applying grayscale masks (white = texture).
Always use bottom Tex button.
Don't use type: Subtractive.		 Used for applying color textures.
Always use top Tex button.		 Used for adding horizontal height contours to an image, similar to a contour map.
Not covered in this tutorial.		 Used for adding horizontal lines of color to a mountainside or cliff side.
See Strata tutorial for more info.

 

Once you've selected Surface Distribution Version, a settings window appears. 

Under Overlay Type, you have 4 choices.  Anything but Subtractive should work, but Total Overlay is probably the best choice.

Under Terrain Size, select the size of terrain you are working with.  In this case, we are using 257x257 which should be the default.

Don't touch Overlay coverage Area.  This will change automatically if you select a different option under Terrain Size.  This would be changed if you want an RGB texture applied to a certain part of the terrain - not a setting that is usually changed for masks.

Tiling is used to repeat a texture a certain number of times in the X and Y directions.  This setting is often used when applying an RGB texture, but seldom when applying a mask (tiling used with a seamless  texture can increase the amount of detail in your image, but tiling used with a mask just repeats the mask pattern).  Leave the tiling at 1 for this tutorial.

Click OK and select "AlienMask.bmp" as the bitmap image when asked.
You might have noticed that AlienMask.bmp is 1000x1000 even though the terrain is set at 257x257.  The pixels are not wasted however.  The higher the mask resolution, the better the detail Terragen renders, regardless of terrain size.

Feel free to do a Render Preview after clicking OK to finish. Notice the colors - coloring my surface layers helps me make sure the masks and Surface layers are correct before I apply textures to those layers.

Pay close attention to the "Coverage" and "Fractal Noise" sliders when applying masks.  A good rule of thumb is to keep them all the way to the left.  If you use Total Overlay, it's not much of a problem, but if you use Transparent or Additive, keeping them all the way to the left prevents Terragen's own distribution system from doing weird things to the image.

 

This is what you see if you select Total Overlay.
It is also what you see if you select Transparent or Additive and have the "Coverage" and "Fractal Noise" sliders to the left.

 

 

 

The image at left is what you see if you select Transparent and have both sliders to the right. The blue has escaped outside the mask due to the coverage slider and the red splotches are due to the fractal noise slider.

  The image at right is what you see if you select Additive and have both sliders to the right.

 

 

Step 3: Texture Time

Now it's time to apply some textures.  Go into the Green Grass Surface Layer and click the top Tex button (the one under Base Surface).  Click the "+" button to add a new Overlay and select RGB Texture Version this time.

Notice that we haven't applied a mask to Green Grass.  Green Grass is the bottom surface layer and Dead Grass will sit on top of Green Grass.  So, we only need to use the top Tex button.

 

This time select Total Overlay - This will completely cover the surface layer with our texture.  It is also the most commonly used setting when applying a texture. 

Additive and Subtractive simply add or subtract the colors of the texture to/from  the current surface layer without covering up any existing textures (for instance, I have used them to modify an area that already has a strata effect).

Again, select 513x513 and leave Overlay Coverage Area alone.

Tiling would normally be used here.  Normally, I use a seamless texture and set the tiling to around 25 for both X and Y for a 513x513 image (this figure can change depending on the size of your texture and depending on the desired effect).
However, for this tutorial, we are going to cheat and use a simple, really big texture, so leave the values at 1.

 

 

Click OK and point SOPack to "GreenLawn.bmp.  When done click OK to close SOPack window.

Notice that the texture images are square? This is important:

Always make sure your texture images are square.

Now, repeat Step 3 except this time go into Dead Grass properties.  Still select top Tex button, RGB Texture Version, Total Overlay, 513x513, and tiling of 1.  Lastly, point SOPack to DeadLawn.bmp and click OK.

 

All done.  Render your completed image.

 If you feel adventurous, try creating your own mask.  Remember that it too should be square.  Experiment with different mask sizes to see how they affect the level of detail in the final image.

Final Note

Currently, SOPack does not save any settings inside the Terragen World file.  Make sure you write down all your Mask and Texture settings before you close Terragen (and while you still remember them).  You will need to reapply SOPack each time you open Terragen.

The good news is that SOPack is currently being re-written and will be able to save (and edit) its settings very soon.

 

questions or comments?
email me