Introduction

In addition to creating maps, MapLink Pro Studio can also be used to create runtime terrain databases or standard terrain formats e.g. DTED0, 1 or 2. MapLink Pro Terrain Databases contain multiple resolutions of terrain data created from one or more sources. These terrain databases can then be used in conjunction with a map to provide runtime terrain information such as height/depth cross-sections or intervisibility information.

The creation of a sophisticated, multi-resolution fused terrain database is a complex process. The following steps provide an overview of this process.

Create a Project. MapLink Pro offers you a choice of Feature Books. This is not required for a Terrain Set, so accept the default.

Add Layers to the Project. Although terrain databases can be created as a number of layers, initially it is best to start with a single layer. Within the layer MapLink Pro Studio builds structures to optimize access to the data, and therefore multiple layers are often unnecessary. Add a layer to the map project you have created.

Add Datasets to the Layers. The Add Datatset dialog includes three types of dataset: Vector, Raster and Terrain. Only import filters selected from the Terrain Tab will be used in generating a terrain database. The order that datasets and datafiles are contained within the project tree is important. The last dataset in the layer will take precedence in the output terrain database.

If you are using different datasets within the project you may need to define the input coordinate system for the dataset. You may also wish to reduce the quantity of data loaded into the project by using input clipping.

Add Data to the Datasets. Add the data and set up any configuration options on the Format Configuration panel for the dataset or for each data file. For all the current terrain import filters it is possible to preview the data using the Auto button to generate shading based on height. This will indicate the coverage and the vertical limits of the data visually.

Define the Output Coordinate System, which is the coordinate system that will be applied to the whole terrain database. A terrain dataset can be output as either a lat/lon grid or a regular grid in a specific coordinate system. You can define a coordinate system for the terrain grid in the same way as for a map, by selecting output coordinate system in the map menu. The default map coordinate system is defined as simply lat/lon.

Your specific application requirements may often dictate that a particular projection must be used. If this is so, it helps to set up the output coordinate system as early as possible, so that you always have a good impression of how the data will appear in the runtime application.

Optimising the Terrain Output

In order to optimize the terrain output you must set up a number of key options.

Tiling:

There are options on the layer menu(Select a Layer in the tree-view and the menu Layer-Tiling that allow you to configure the terrain tiling. The terrain database consists of a set of separate tiles each containing terrain at multiple resolutions in order to optimize retrieval performance.

If high resolution terrain exists in the source data which falls into a specific tile MapLink Pro will build the entire tile at the resolution required to store the terrain patch selected. Thus setting the tiling correctly is fairly critical. You can set the tile size - if you are using lat/long then the tile size is in degrees, so the default is 10 degrees x 10 degrees. You can also control the maximum level of detail that will be stored in one tile, irrelevant of the source resolution. But if you have high resolution terrain you need to reduce the tile size so that tiles do not become too big.

If you do not setup the tiling the data tiling is used.

Terrain Pyramid nugget Size

This can be set on the Tools-Options-Processing page.

Create the Terrain Database

This option can be found in the Map Menu. As well as creating a terrain database, you also have the option of creating fused DTED data at levels 0, 1 or 2.

Preview the Terrain

You can use the MapLink Pro Terrain Viewer to check that the output terrain works as you expect. This is located under the MapLink Pro options in the Start menu. Load a MapLink Pro map the output coordinate system isn't important - and then use the Load Terrain option to open the terrain database you have created