Grome Terrain Modeling with Ogre3D UDK and Unity3D: A Comprehensive Guide

These kinds of maps are known as heightmaps. However, any information that can be represented in the grid pattern can use maps. Additional maps can be used by 3D engines to tell it how to mix many textures together; this is a common terrain painting technique known as "splatting". Splats describe the amount of blending between texture layers. Another kind of map might be used for lighting, adding light, or shadows to an area of the map. We also find in some engines something called visibility maps which hide parts of the terrain; for example we might want to add holes or caves into a landscape. Coverage maps might be used to represent objects such as grasses, different vegetation layers might have some kind of map the engine uses to draw 3D objects onto the terrain surface. GROME allows us to create and edit all of these kinds of maps and export them, with a little bit of manipulation we can port this information into most game engines. Whatever the technique used by an engine to paint the terrain, height-maps are fairly universal in how they are used to describe topography.

grome terrain modeling with ogre3d udk and unity3d

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Huge landscapes may require a lot of memory, potentially more than a 3D card can handle. In game consoles memory is a scarce resource, on mobile devices transferring the app and storing is a factor. Even on a cutting edge PC large datasets will eat into that onboard memory especially when we get down to designing and building them using high-resolution data. Requesting actions that eat up your system memory may cause the application to fail. We can use GROME to create vast worlds without worrying too much about memory. This is done by taking advantage of how GROME manages data through a process of splitting terrain into "zones" and swapping it out to disk. This swapping is similar to how operating systems move memory to disk and reload it on demand. By default whenever you import large DTED files GROME will break the region into multiple zones and hide them. Someone new to GROME might be confused by a lengthy file import operation only to be presented with a seemingly empty project space.

GROME will let you create such large worlds. Its own Graphite engine handles them well. Most 3D engines are designed for smaller first and third-person games which will have a practical limit of around 10 to 25 square kilometers (1 meter = 1 unit). GROME can mix levels of detail quite easily, different regions of the terrain have their own mesh density. If for example you have a map on an island, you will want lots of detail for the land and less in the sea region. However, game engines such as Unity, UDK, and Ogre3 Dare are not easily adapted to deal with such variability in the terrain mesh since they are optimized to render a large triangular grid of uniform size. Instead, we use techniques to fake extra detail and bake it into our terrain textures, dramatically reducing the triangle count in the process. Using a combination of Normal Maps and Mesh Layers in GROME we can create the illusion of more detail than there is at a distance.

A new Grome book is available from Packt Publishing, author Richard A. Hawley: Grome Terrain Modeling with Ogre3D, UDK and Unity3D This is a great introduction to Grome modeling that also deals practical editing details and with integration of the scene data into well known engines: Unity3D, Unreal (UDK) and Ogre3D. We fully recommend this book for our customers that want a smooth introduction to Grome and its integration with engines. For more details, table of contents and additional materials please refer to Packt Publishing book page.

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