Custom Terrain Building Service
Terrain can be built up from standardized objects, such as ActiveWorlds land* set. This can be tedious and lack realism, but is the only viable solution in a public building world. In your own world however, possibilities exist for a custom terrain.
There are three ways to implement custom terrain:
- Currently, when someone talks about terrain, most people automatically think of the built-in terrain which can be edited from within the AW browser by any user with caretaker rights in that world. This type of terrain can also be created by using a bot and a heightfield file to feed the elevation data into the bot.
- A custom terrain can also be implemented as a one-piece ground object. This is typically done with a modeling program or a heightfield to RWX converter. This type of terrain will either be an RWX file or a COB file (depending on how it was created).
- The oldest custom terrain generation technique was to start with a heightfield file, then translate that into a series of RWX terrain tiles by a heightfield to RWX converter. Each terrain tile is an object of a fixed size (say 20 x 20 meters) and they are typically designed to fit in a specific location in your world and butt up against each other with no gap or overlap.
Which Type Of Custom Terrain Should You Use
Each of the above approaches has its advantages and disadvantages, and can even be combined with each other, to the point of all three being used in a single world! Because the built-in terrain method has been improving with each major revision of the ActiveWorlds software, only the latest revision (v3.5) will be considered here. If your world is in a "universe" running older software, there will be additional disadvantages of the built-in terrain, assuming it even exists for you at all.
|Built-in Terrain||Fastest rendering.
Visible out to Max View/Fog Distance (currently 1200 meters, maximum).
Editable by world owner after delivery (within buildable limits only).
Size is apparently unlimited.
Can be used for terrain far beyond normal building limits if a bot is used.
Terrain extends out even beyond what the terrain bot has built, set at the default altitude.
|Single sided only, invisible from below.
Only a single layer is possible.
Vertex spacing fixed at 10 meters, limits detail possible.
Crude LOD (Level Of Detail) rendering speedup in browser can cause odd rendering artifacts.
No control over how quad is split into triangle pair, can cause undesired effects with diagonal features.
|One-Piece Ground||Visible out to Max View/Fog Distance (currently 1200 meters, maximum).
Other objects can be added to one-piece ground (difficult, but possible).
Can be used for terrain far beyond normal building limits.
Can be renderable from both sides (slows rendering).
Multiple layers possible, perfect for floating islands in the sky, caves, etc.
|Slowest rendering if poorly designed (can be a lot of work to do it right).
Practically speaking, only editable using special software.
Size limited by practical considerations of object and file size.
Cannot be combined with Tiling Ground Object option.
|Terrain Tiles||Good rendering speed, even with fairly high detail.
Can be renderable from both sides (slows rendering).
Multiple layers possible, good for floating islands in the sky, caves, etc.
Perfect for smaller than world-sized elements, such as a mountain or a cave, which can be placed in different locations within a world.
World owner can move terrain around after delivery, without the necessity of using a bot.
Incremental changes are possible (say if the world sized is increased) by replacing only those tiles which reflect the changed heightfield data.
Possible for world owner to do minor edits to an object tile using Notepad, after delivery of terrain (e.g. to add a hole).
|Visible only to Object Visibility Distance (currently 200 meters, maximum).
Depending on lighting settings set inside the tile objects, seams between tiles can be visible.
Normally only editable using special software.
Beyond normal building limits only a limited overhang is possible (typically 100 meters or less).
Size limited by practical consideration of number of files added to models directory.
Any builder with Eminent Domain rights might accidentally shift or delete a terrain tile.
Takes a tiny amount of building space in the cell.
My Preferred Workflow
My approach to creating custom terrain is to start by creating a heightfield file in a special program called a heightfield editor. Once this is complete, I use a second program to output a terrain using any of the above three approaches. Often time there is some post processing necessary to tweak the final terrain.
My heightfield editor of choice is Leveller, by Daylon Graphics . Leveller gives superb control of the editing process; featuring brushes from a single data point up to 100 data points in diameter, plus filters such clipping, noise, erode and others, and the ability to combine heightfields. You can also overlay the heightfield with exact position information, for example marking the precise vertexes along the outer boundary of the world, as well as working directly in meters. Vertical data is stored as 32-bit numbers, giving far more precision than attempting to use non-specialty tools for the task.
Although Leveller is capable of directly outputting a one-piece ground object with variable vertex spacing, for most of my heightfield to terrain work I prefer to use Andras Sarkozy's DEM2RWX , which can create terrain using any of the three approaches. DEM2RWX can import many heightfield file formats including direct support for Leveller format TER files. Textures are selected and applied to the resulting terrain based on slope and/or altitude. Unfortunately, DEM2RWX lacks the control necessary to apply textures for pathways and other fine features. Fine control of textures must be done in a post processing step. For built-in terrain this post processing can be done in the AW browser by the world owner. For RWX output, such as a one-piece ground object or terrain tiles, post processing is done directly on the RWX file(s).
I feel some of the strongest advantages of this work flow are: The ability to see the entire terrain all at once. The ease of fixing gross errors, such as sliding an entire mountain range over a few meters, or a few kilometers. The ability of knowing where each data point of the heightfield lies with respect to the world and working directly in world units.
A Few Examples Of My Work
Over the years I've had the opportunity to do a few terrains.
My own world, SkunkWks has seen a succession of terrains, using either: Terrain tiles blended with a ground object, a one-piece ground object, or terrain tiles blended with the built-in terrain. To create what I have envisioned for SkunkWks in a timely fashon, I'll need some custom software.
Over the past several years I've had the chance to create terrain for the Amazons world group . Three of the five past revisions of Amazons, and one each for AzNPeaks and AzNWoods. These projects used: Terrain tiles blended with existing builds plus a custom ground object, or the built-in terrain.
A current project is the basement level of MtnMyst world. Previously, I'd done a terrain tile and custom ground object version of this world on a completely different theme.
I'd also created a speculative terrain for a potential customer to try out a concept. He did not take the terrain, having a prior comitment, but the concept remains interesting. This project used the built-in terrain and in the interest of time, was not properly textured.
I've tried a few complex multi-layered projects, such as caverns , which look as mind blowing as they have been difficult to make. I think the key to such a project is to limit the overall scope.
Over the years I've learned a lot. Perhaps what not to attempt is just as important as what works. I've learned that good textures are critical to realism, and can in themselves be very time consuming. I've learned that projects that rely on a lot of hand tweaking are most certainly doomed. Amazons v2 and v5 were a great successes, v5 was a full one-million vertexes and the project went fast and smooth once the textures where ready. MtnMyst/Galway will be another winner once the textures are done. And complex projects like caves are best when limited in scope.
Do you have a terrain project in mind? Let's talk.
Working With The World Owner
Finding just the right textures for use on a terrain can really make a difference with the realism and can be a very time consuming step. If a world owner wishes to supply their own textures this can save me a lot of time. However, best results happen when the textures meet some rather exacting standards.