Introduction:

The new terrain type used in Microsoft Flight Simulator 2000 is called "Elevated Mesh" and it provides a realistic description of the shape of the earths surface. After the release of FS2000, Microsoft provided terrain tools to create such elevated mesh and programs like FSMESH are available to help in the design of the under laying digital elevation maps (DEMs) and for the purpose of integrating mesh and scenery. The major criticism of the default approach was that the coverage of the mesh with textures was fixed, and that no way existed to change it. For much of the world, the coverage supplied by Microsoft was much less than optimal: for example, the airport of Frankfurt is surrounded by city textures in a default installation of Flight Simulator, while in reality it is surrounded by forest. Therefore many people attempted to modify the textures, but this approach turned out not to work. The biggest difficulty was working out where the data which specified texture placement was stored - obviously, the information to place all textures of the world cannot be held in a small file, which was the one clue I had.

| In the end, it was by chance that I discovered that the texture information was stored in the file ..\scenery\worldlc.bgl. I verified this by replacing the same file in an early version of FS2002 with FS2000 one - the coverage of the mesh immediately looked like the FS2000. Further experiment revealed that installing a suitable file in the same directory overwrites the default, so all you have to do is to place an appropriate file there. Note that to my knowledge land class scenery files of type .bgl need to be in that specific directory and that they have no effect if placed in any other directory.
| After a great deal of research I have discovered that it is possible to create a special form of mesh file which contains texture data. The programs that come with the FS2000 Terrain SDK will do this for you, if you provide them with suitable data and information files. Some time was needed to find how this worked, but once I cracked the format, the problem was solved. So for FSLandClass to work, you need the FS2000 terrain SDK.

You see here the examples of two German cities, Karlsruhe above and Koblenz below. These are not as they appear in FS2002, where Koblenz does not exist at all. This is how they should be - and how you can produce them with FSLandClass.

How does FSLandClass work?

FSLandClass needs a suitable input file to resample, and a suitable information file containing the data. First, some general rules have to be mentioned.

1) Every land class scenery consists of 256x256 land class squares, or a multiple of this. To keep things easier ( they will become complicated enough anyway,) just stick with this size. If you want to create landclass files spanning large areas, you can combine several land class TMF - Files using the TMFMERGE utility later on. So, we will refer to land class files as 256 x 256 land class squares throughout this tutorial.

2) Since the textures underlying the auto generated scenery are not scalable, the size of each land class file is fixed at 3.75 degrees in an East-West direction, and 2.8125 degrees in a North-South direction. Thus, the earth is divided into 96 land class files running East-West and 64 land class files between the poles, with fixed limits. It is possible to make the dimensions of the files smaller, but if you do that parts of the earth surface remain as uncovered sea. This is why FSLandClass enforces these limits - it makes things much easier in the end.

3) As consequence, the size of each land class square is approximately 1.2 x 1.6 km at the equator and slightly narrower away from it - for example at around 50 degrees north or south squares are 1.2 x 1.2 km. As a rule of thumb, you have one byte to describe the texture usage and the auto generated scenery of an area of 1.2 x 1.2 km. This single byte is how billions of trees and millions of buildings fit into the FS2002 landscape without using hundreds of CDs.

4) Since we do not know how to extract the compressed information from the FS2000 or FS2002 mesh type files, there is no way to exchange single land class squares. You always have to exchange a complete land class file, and that means that you need to design an area of typically 300 x 300 km. I know that most of you actually want to design small areas of only a few squares, which means that the utility you require not only needs to be able to do that, but has to be an integrated software system with a user friendly interface and several classes of geographical data in order to bring a basic land class of at least comparable quality to the one on the FS2002 CD, so that you can start improving things rather than reinventing the wheel.

5) Supplying these geographical data also means that you only need material for the area you are working on, and not for the whole land class file. To do this on your own is difficult - suitable maps on CD for Germany alone cost about $1000, so the investment needed for any design would go beyond the means of all but the richest individuals.

6) Do not that all land class .BGL files have to be placed into the FS2002\scenery folder directly, I have never got them working in another directory.