There are two ways to identify the boundaries of your terrain. These methods can be use separately or in combination:
METHOD 1: Manually Select Terrain Boundary. If you have already consulted a world map or an Atlas and already know the particulars of the region for which you want to create a terrain, you can input them directly. Selecting Map -> Region from the menu bar will open the Map Region Defination window illustrated below:
The definations for each input variable are:
Center Latitude, Center Longitude are those values that correspond to the center point of your region of interest. Values are provided in units of degrees.
Map Width, Map Height are the total distances you want the region to encompass. Values are provided in units of kilometers.
The figure below illustrates these parameters for the region used in the Target Korea mod:
Resolution sets the size that each terrain square will be displayed within the Targetware simulation. For example, in the Target Korea mod, a value of 0.25 kilometers/pixel is currently used. This means that each square making up the terrain will measure 0.25 kilometers, or 250 meters, on a side in game-world dimensions.
The value that you select for resolution has three major impacts:
- It establishes how smooth your terrain will look in game. The smaller the value, the smaller the polygons and more realistic looking terrain. The downside to this is, as you make the resolution smaller and smaller, you will force the drawing of more and more polygons. As the number of polygons increase, your terrain will begin to negatively affect the frame-rate of the Players flying in your world. There is a trade-off here that you will have to experiment with. Our experience at Targetware is that 0.2-0.25 km/pixel provide a nice compromise.
- As smaller values are used for resolution, the size of your terrain files will grow. Since Players using your terrain will have to download these files, it can be a concern should the files get very large.
- The size of each terrain square will affect how your draw your individual terrain textures (farms, forests, rice paddy, etc). If you make terrain textures that have objects drawn on them, you'll want to make sure you draw them appropriate for the resolution of the terrain. Otherwise you could end up with trees, roads, etc that look huge (or tiny) when rendered in the game-world.
Map Projection - Since we are taking data that is from a sphere (Earth) and putting that data onto a flat surface (our terrain), a selection of transformation method must be made. Four common projections are provided via the pull-down tab: Geographic, UTM, Equidistant, and Equal Area. For purposes of terrain creation, it is recommended that the Equidistant projections be used. This particular transformation has been created to best preserve the distance scale, which is important for recreating proper flight distances.
METHOD 2: Crop to Selection. The second, and probably the most common, method for picking a region for your terrain, is through the crop tool. The crop tool allows you to draw a box around your region of interest. Selecting Tool -> Crop from the menu bar will activate this feature:
Once the crop tool has been active, holding mouse-left-click and then dragging your mouse will create a selection box. Make sure your region of interest is within the box, then release the left mouse button.
When the button is released, the Map Region Defination window described in the previous section will appear with all information pertainant to the region you just selected in its input areas. After selected "OK", the viewing window will transition and the output window will now contain the newly selected region. You can continue to crop the selection until you have fine-tuned the area to your liking.
