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Terrain Mode

Terrain Mode is a toolbox mode new in UnrealEd 3 which allows the mapper to manipulate terrain. It is a very complex swiss army chainsaw (!) of a tool, which allows heightmaps and layer maps to be imported as well as edited on the fly.

To enter this mode, click on the toolbox terrain mode icon (the mountain with snowy peaks); this pops up the Terrain Editing window. To close the window and leave this mode, pick another mode from the toolbox such as the Camera Movement mode.


The Terrain Editing window, with its icon highlighted

The Terrain Editing window

The Terrain Editing Window is a floating window, of fixed size, with 2 top-level tabs on it:

  • Tools : Allows you to edit your terrain, add layers etc.
  • Misc : commands to run the terrain generator.

We'll mainly be concerned with Tools.

The Tools Tab

  • In the upper left is a list of the available tools.
  • In the upper middle and right are options with apply to the tools. Check "per tool?" so each tool remembers its own settings; otherwise they will apply to all the tools.
  • The lower half of the window has another set of three tabs, which we'll call the Terrain Layers tabs. This is where you select what the tools will act on – the heightmap, the texture layers, or decoration layers.

The different tools and the brush

All the tools have the same basic interaction interface. Pick a tool from the list by clicking on it. You need to use them all in the 3D UnrealEd viewport, where the active "brush" is represented by a yellow circle indicating the radius of effec. This yellow circle follows the surface of the terrain, and indicates the inner & outer radius settings. It's a good idea to set the viewport to "wiremesh" view to see vertices more clearly.

You use the control key in combination with either the left or right mouse button to use a tool. In general, if control + left-mouse does one thing, control + right-mouse does the opposite.

The tools are:

Vertex Editing
see Vertex Editing Terrain Tool
(please fill in )
This behaves differently according to whether the leightmap or a layer is selected in the lower three tabs. More: [Painting Terrain Tool]?
raise (LMB) or lower (RMB) the terrain by an amount determined by strength and adjust. The mouse must be moved to effect a change. Set the strength and adjust to quite low with this tool, or large changes will result very quickly.
Mask or un-mask the layer.
This will cause the terrain inside your editing circle to blend together and become, well, smoother. This can be looked at as a sort of "averaging" tool, where everything in the area is averaged together towards a middle height. For instance, if you pumped up the radius to much larger than your terrain area with strength of 100%, holding down the LMB would cause you to get, eventually, a flat piece of terrain with the average elevation that all of your terrain had. NOTE: Smoothing off the edge of the terrain is BAD, resulting in an instant UnrealEd crash. Save often.
introduces random changes, raising the terrain in random places by an amount determined from the strength and adjust. Useful for roughing up flat areas to make them look more natural.
Ctrl + LMB on a terrain vertex, then wherever you drag the mouse will be set to the height of that initial vertex. Useful for creating 'man-made' areas in the terrain e.g. roads.
This tool is used to show or hide individual polygons and regions of the terrain. What you can't see, you can't touch, so use this tool to make e.g. entrances to caves that allow the player to pass through the terrain. Obviously, you will just drop through any hole to the bottom of the containing subtracted brush, so you need to add [BSP geometry]? around the hole then subtract a cave, or put a static mesh there. The tricky bit is aligning the subterranean part seamlessly with the terrain. See DM-Antalus for a good example.
Edge Turn
Tex Pan
Tex Rotate
Tex Scale

Most terrain editing is done using Painting, Smoothing, Flatten, and occasionally Visibility. The others are useful for very fine control.

The Tool Options

The tools options section changed the settings for the yellow brush you see in the 3D window: its size, and how much it affects the terrain. It is very important, so get used to it, you'll tweak it often :). It consists of 4 options:

Inner Radius & Outer Radius
these are pretty self-explanatory. They control the the overall size of the brush (the outer radius), and the "softness" of the edge of the brush. If you're a Photoshop user this will be very familiar. Basically, if the inner & outer radii are the same, the effect of the brush is consistent across the entire circle of effect. If the inner radius is smaller than the outer radius, the strength of the brush will taper, from full strength within the inner radius, to zero at the outer radius.
Per Tool?
Each tool remembers its own settings.
Lock icon
Tie the Inner Radius & Outer Radius sliders together
Strength & Adjust
These are sort of like opacity and pressure in Photoshop – they control how much the brush does, and how fast it does it. Larger values for Adjust and Strength will cause modifications to your terrain to happen much faster – often too fast.
Ignore invisible quads
doesn't work, apparently
lets you work on 2 or 4 parts of your terrain simultaneously

It's pretty intuitive once you've done it a couple of times. When you can see the effect of different settings immediately on how fast that hill rises, and what its shape is, it becomes quite obvious! Experiment a lot – experimentation is rewarded. Recommended settings will be given when treating the individual tools, but for an example, here's the settings that I typically use for the Smoothing tool:

Inner Radius: 0

Outer Radius: 1024 or larger (sometimes as high as 8192)

Strength: 8%

Adjust: 4

In summary:

  • All terrain editing is done in the 3D view (use the wiremesh viewmode to see terrain vertices more clearly).
  • The brush is a bright yellow circlet
  • Use the control key in combination with holding down the left or right mouse buttons to use a tool.
  • Strength & Adjust are critical, and usually best kept very low for fine editing
  • Experiment, experiment, experiment!

Terrain Layers tabs

Select here which component of the terrain is affected by the tool you use.


Lists all terrains currently in your map, listed by the name of their heightmap texture (so if you change these, beware!). Select the one to you want to work with from the list. Double-clicking on the name in the list brings up the Actor Properties for that terrain's TerrainInfo.

Click the New icon to make a new terrain. The terrain will be centered on the 3D UnrealEd Viewport camera (we think!). The zone you are in needs to be set to have bTerrainZone = True. See Creating A Terrain for this in detail.


Lists the Terrain Texture layers of the current terrain. You can use this area to add new layers and reorder them.

Select a layer here to make the Painting Tool alter that layer's visibility on the terrain. (if nothing seems to happen, remember the display order of the layers: the top layer in the list is the one rendered first, so lowest.)


Create and edit Terrain Decoration layers.

Misc tab

The misc tab holds the settings for the terrain generator. This generates random terrain within the region currently highlighted with the [Select Terrain Tool]?.

Can't think of how you want your terrain to look? Want UnrealEd to give you something more interesting to start with? Use the terrain generator.

Controls how many passes the generator makes over the terrain. More steps mean more hills.
Controls the magnitude of the hills being generated. Max value 255. High values mean steep, craggy peaks that leave almost no place to walk, and low values mean gentle rolling hills that are pretty flat overall.
Use entire Heightmap?
Tick this to have the generated surface use all of the terrain space. Unticked, only uses what is currently selected with the Select tool in the terrain editor.


I can't adjust the terrain! LMB + RMB + Ctrl = nothing happens
The file format of the terrain heightmap is very important. If it's not G16, then you won't be able to edit it properly (if at all) with the tools. If importing your own heightmap, make sure it's 8-bit grayscale, import it, then right-click it on the 'terrain info' tab and convert it to G16.

Related Topics

External Links


EntropicLqd: Try this thread - it uses the UDN tut as a basis and lets you know where things go wrong or stop working. http://ina-community.com/forums/showthread.php?s=&threadid=216389. Then you can fill this page in yourself :) And make it easier to follow.

Icedude:We realy need a tutoral on Deco Layers. I cant figure them out!

Tahngarth: could we integrate this with Using The Terrain Tool somehow? This part seems more a description of the tools than a step-by-step tutorial. Part I is quite important and well done tutorial, but this part seems just a tool function summary. I'm not sure what to do here, but theres bound to be some duplication going on if i finish writing that page now.

ProjectX: Ok, i've dun terrain before, and mastered it, I have a cavern set up with two terrain actors, one above the other, they used to be using the same heightmap, but i changed it. Now, i place playerstarts, and rebuild, they come up with "this player start is not on an even base or neer a steep slope", i finally got that to stop and i tested the game and it said it couldnt find the player starts. I had 17 on there and i had rebuilt the level without a single error. I tried loading the map up again and it GPFd

ZxAnPhOrIaN: What type of rebuilding did you use? If you did geometry, use the path rebuild button. If you did paths, use the geometry rebuild button, and then use the path button. That happened to me once.

MadNad: Another interesting thing to note that I found was that by increasing the size of your heightmap when creating terrain layer from 128x128 to 256x256 makes some pretty crisp shadowing, along with longer compiles and lower frames, but still, very cool feature.

Category Mapping
Category Troubleshooting

Category To Do – fill in the other terrain tools

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