TerrainViz

Interactive rendering of large terrain data. More...

Classes
class	SoTViz
	Static class used to initialize the TerrainViz extension. More...
class	SoTVizDataPreprocessor
	Class used for elevation preprocessing. More...
class	SoTVizPreprocessor
	Abstract class used for elevation and texture preprocessing. More...
class	SoTVizRender
	Renders the terrain. More...
class	SoTVizTexturePreprocessor
	Class used for texture preprocessing. More...
class	SbTVizColorScale
	Class to manage colorscales More...
class	SbTVizData
	Abstract base class for elevation data. More...
class	SbTVizRegularGridData
	Regular grid data class. More...
class	SbTVizTexture
	Texture class. More...
class	SbTVizTextureList
	Handles the quadtree of textures. More...
class	SoTVizAltimeterSpeedometer
	Class for displaying motion information. More...
class	SoTVizCameraManager
	Abstract class for managing the SoTVizViewer camera. More...
class	SoTVizCompass
	Class for displaying an orientation compass. More...
class	SoTVizControls
	Class for managing the SoTVizViewer control dialog. More...
class	SoTVizControlsMenu
	Class displaying a toggle button in SoTVizViewer control interface. More...
class	SoTVizNavigationToolBase
	Base class for SoTVizViewer navigation tools. More...
class	SoTVizNavigationTools
	Class for SoTVizViewer navigation tools management. More...
class	SoTVizViewer
	Abstract base class for SoTVizViewer. More...

Detailed Description

Interactive rendering of large terrain data.

DEPRECATED: TerrainViz is deprecated and no longer supported since OIV 9.5.

NOTE: The classes in this extension do not exist in Open Inventor 10.0 and later.

The TerrainViz extension provides a powerful tool for GIS, geoscience, and military simulation applications by allowing interactive rendering of large textured terrain.

NOTE: TerrainViz is a not separately licensed extension. You must have an OpenInventor license string.

Introduction

The TerrainViz extension performs terrain visualization using an auto-adaptive mesh technique and a quadtree of textures.

It uses a multi-resolution technique that re-meshes the terrain at every frame with a constant number of triangles. The local mesh accuracy depends on the point of view and the altitude gradient. The texture level depends on the point of view only.

The module renders the terrain at an approximately constant frame rate.

Controls are provided for adjusting quality versus performance.

The TerrainViz implementation is based on the ROAM (Real-time optimally adapting meshes) algorithm:

https://www.llnl.gov/graphics/ROAM

Requirements and Limitations

TerrainViz currently provides a low level API that imposes constraints on the input:
- Terrain geometry must be a regular sampled grid.
- A quadtree of textures must be provided for LODs.
Terrain and textures must fit in memory. No automatic disk paging is provided to handle very large terrains.

Summary of Classes

SoTViz Initialization class
- Used to initialize and get information about the TerrainViz module.
SoTVizRender Terrain rendering node class
- Manages the elevation data and the textures.
- Recomputes the mesh.
- Loads and generates TerrainViz XML files.
SbTVizData Elevation data class
- Stores the elevation data (abstract class).
- Returns information about the data.
SbTVizRegularGridData Regular grid data class
- Stores regular grid elevation data.
- Returns values.
SbTVizTexture Texture class
- Stores an image file and its attributes relating to the texture quadtree.
SbTVizTextureList Texture list class
- Handles the quadtree of textures.

Using TerrainViz

Here are the basic steps for using TerrainViz.

Initialize the module using the SoTViz class:
```
         SoTViz::init();
     
```

Create and add an SoTVizRender node to your scene graph:

         dtmRender = new SoTVizRender(); 
         root->addChild(dtmRender);

Fill this node with data and textures. This node can be filled two ways:

Via an XML file describing the terrain (elevation data + textures). For example:
```
           dtmRender->loadFromXML("data/africa.xml");
     
```

Or by using the basics SbTVizTextureList and SbTVizRegularGridData:
(SbTVizTextureList is filled by multiple SbTVizTexture instances)

         data = new SbTVizRegularGridData(); 
         data->loadDataFile("data/africa_binary.dat", SbVec3d(1./4097., 1./2500., 1./4097.), SbVec3d(0., 0., 0.)); 
         dtmRender->setData(data); 
         texList = new SbTVizTextureList(); 
         texList->addTexture("data/africa_1_1.jpg", 0, SbVec2s(0, 0)); 
         texList->addTexture("data/africa_1_4.jpg", 1, SbVec2s(0, 0)); 
         texList->addTexture("data/africa_2_4.jpg", 1, SbVec2s(0, 1)); 
         texList->addTexture("data/africa_3_4.jpg", 1, SbVec2s(1, 0)); 
         texList->addTexture("data/africa_4_4.jpg", 1, SbVec2s(1, 1)); 
         texList->addTexture("data/africa_01_16.jpg", 2, SbVec2s(0, 0)); 
         texList->addTexture("data/africa_02_16.jpg", 2, SbVec2s(0, 1)); 
         texList->addTexture("data/africa_03_16.jpg", 2, SbVec2s(0, 2)); 
         texList->addTexture("data/africa_04_16.jpg", 2, SbVec2s(0, 3)); 
         texList->addTexture("data/africa_05_16.jpg", 2, SbVec2s(1, 0)); 
         texList->addTexture("data/africa_06_16.jpg", 2, SbVec2s(1, 1)); 
         texList->addTexture("data/africa_07_16.jpg", 2, SbVec2s(1, 2)); 
         texList->addTexture("data/africa_08_16.jpg", 2, SbVec2s(1, 3)); 
         texList->addTexture("data/africa_09_16.jpg", 2, SbVec2s(2, 0)); 
         texList->addTexture("data/africa_10_16.jpg", 2, SbVec2s(2, 1)); 
         texList->addTexture("data/africa_11_16.jpg", 2, SbVec2s(2, 2)); 
         texList->addTexture("data/africa_12_16.jpg", 2, SbVec2s(2, 3)); 
         texList->addTexture("data/africa_13_16.jpg", 2, SbVec2s(3, 0)); 
         texList->addTexture("data/africa_14_16.jpg", 2, SbVec2s(3, 1)); 
         texList->addTexture("data/africa_15_16.jpg", 2, SbVec2s(3, 2)); 
         texList->addTexture("data/africa_16_16.jpg", 2, SbVec2s(3, 3)); 
         dtmRender->setTextureList(texList);

Adjust some parameters.

       dtmRender->maxRenderedTriangles = 3500; 
       dtmRender->triangleSizeAttenuation = 3.2; 
       dtmRender->distanceAttenuation = 3.15;

Example Program

An example program is available in $OIVHOME/examples/source/TerrainViz.