Old Forest FAQ

Forum for Discussions

You can discuss with me or read about new developments in the X-Plane.org Forum where I’m active on – mostly – daily basis. You can find me as the user alpilotx. My most active thread for the forests is: this forum thread

Hardware Requirements

he hardware requirements for forests are in the higher range.

  • 1GB of RAM is an absolute must, and is only enough for some moderate forest density. If you want to enjoy the full beauty you should consider 1.5 GB or better 2 GB of RAM (or even more).
  • From the graphics card side, I used it with a GeForce 6600 GT with “only” 128 MB RAM and it worked fairly well. So here you don’t have to go for the most expensive hardware (bot of course, with high density forests you will see your fps going down). The newest (often called DirectX 10 compatible) graphics cards – but at least from the “performance segment” – should have no problems to handle the forests.
    IMPORTANT notice for GeForce 7xxx users: I had reports from users, who had issues with jerky graphics (FPS ok, but jerking when flying faster). It turned out, that at the moment the best solution is to use the –no_fbos startup parameter of X-Plane with those cards. With that setting, graphics are smooth again.
  • My previous Athlon 64 3500+ CPU could handled the forests well. I think you can try it with a little slower CPU, but I wouldn’t recommend to go much slower. Currently I’m running it with Core 2 Duo E6600 (of course, without problems). Nowadays I recommend dual cores, as they help big time during scenery loading (which can also happen during flying, when a new scenery tile is loaded in the background).
  • Disk requirements:
    • 590 MBytes for complete V8 Europe scenery
    • 660 MBytes for complete V9 Europe scenery
    • 670 MBytes for complete V8 USA East scenery

since X-Plane 9.00:

  • Thanks to a completely overhauled rendering engine, the RAM requirements could be reduced dramatically (for most situation, even at higher forest densities, 2GB should be sufficient).
  • Because of other new rendering features, the required 3D hardware could be set a little bit higher than in X-Plane 8 (but with some rendering options, this can be balanced out).

And to get the most out of you hardware, I recommend to reed the paragraph about Performance Tuning.


This installation guide is the same for every scenery you can download here. It is the same for X-Plane 8/9 and USA/Europe.

As a first step you have to download at least three things:

  1. Texture set
  2. Forest definitions
  3. Scenery file(s) – one or more, depending on how large of an are you want to cover with forests.

The next part describes all the steps needed for installation. Please follow them carefully to avoid problems.

  1. Everything described here happens inside the “Custom Scenery” folder of X-Plane. So, go to the Custom Scenery folder.
  2. Create a base folder called “CORINE_Europe” or “USA_Forests” (depending on which scenery you install BUT you might also choose any other name you like) in the “Custom Scenery” folder (where you should be already).
  3. Unzip and copy all FOR files from the forest definitions ZIP file to the base folder.
  4. Unzip and copy all texture files from the texture set ZIP file to the base folder. This might be one or more PNG files
  5. Create an “earth nav data” folder in the base folder (here you can’t choose an arbitrary older name, so be careful!). This will be the place for all the scenery files.
  6. Inside the “earth nav data” folder you will have one subfolder for each 10×10 degree scenery package. Each of those subfolders will contain the DSF files from one scenery ZIP file.
  7. Unzip the contents of a scenery ZIP file and put the resulting directoy in the “earth nav data” folder. I will show this on an example:
    • You have the ZIP file corine9.1.0.+40+000.zip
    • This ZIP file holds all DSF files for the scenery subfolder +40+000.
    • If you unzip this file, you should get the subfolder +40+000, and a bunch of DSF files in it.
      If your unpacker only gives you DSF files without a folder, please create that folder yourself and put the files in it. The name of the folder should always be the same as the coordinate part in the ZIP files name (you remember: corine9.1.0.+40+000.zip –> +40+000)
    • Move this complete folder – with its contents – to your “earth nav data” folder.
  8. Repeat step 7. for all scenery files you have downloaded.

Your directory/file structure should look like this in the X-Plane\Custom Scenery folder. (This is only an example which mostly uses symbolic names. Those names can and will vary in the different sceneries. So your texture file might be called Europe_trees.png, or you will have many more .for files with different names. Also, you will have more or other scenery subfolders in “earth nav data” but they will have the same name structure.):
Nothing more has to be done, and now you have to go to an airport, which is covered by the downloaded/installed tiles.

Performance Tuning

The new Version 2 forest scenery is in some cases even more demanding than its predecessor. For this reason I have provided 6 different forest definition sets to play with. They should help – even on older hardware – to use the forest (of course, not in its full glory – but better than nothing). Together with the “Rendering Options” of X-Plane, you now have a good chance to get it running. So, what options do you have, to get the best out of your computer?

    1. Choose between 1-quad or 2-quads.
      1. You have the choice between 1-quad or 2-quads. This decides, if X-Plane uses only one polygon (like a bilboard) for one tree, or two polygons (like two crossing bilboard). Of course, the latter looks much better, but it also almost doubles your memory requirements. So if your computer is trashing (swapping all the time) you should definitly go back to 1-quad and try again.
      2. Then you can choose the visibility distance of 8 miles, 15 miles or 25 miles. Of course, again the farther you want to have trees, the worse for your RAM. I have managed to use 25 miles, but only with the 1-quad option (on 2 GB machin and Linux).
    2. Choose forest density in Rendering Options.
      This setting affects two sides. On the one, you have the visual quality. The higher the density, the better your forests look. But it also directly affects memory usage. Of course, the higher the density, the higher the RAM usage. Now you have two options to ballance the memory issue: you can choose a more demanding forest definition package but lower the density, or the other way around (lowr forest definition, higher density). This gives you the flexibility, to decide, what is more important: visual quality or performance – but still get some trees.
    3. Choose world detail distance in Rendering Options.
      This option – at least from my observation – doesn’t change RAM usage (denisty and forest definition already tell, what geomatry X-Plane should build in memory). But it tells X-Plane, how far out it should drwa objects (this setting not only affects forests, but city objects, cars on roads etc.). The higher you set it, the more strain will be put on your grphics card and CPU. I can tell you, that even with the setting very low you will have beautyful forests, but they will stop at a closer distance (and you hardware will like this). I have pushed this up to default and I think, this was the limit for my hardware (which at the moment is: Athlon 64 3500+, GeForce GT6600 (128MB RAM) and 2 GBytes of RAM and SUSE Linux 10.1). But with the setting default you get already a very, very impressive scenery (as you can see trees pretty far away – I would say, this setting gives roughly the visibility distance defined in the forest definition files).
    4. Choose the right Location (where you fly).
      Memory usage, and rendering performance also depend very much on the location you choose to fly! This is because of the two factors. The forest definitions present in the area and the amount of forests in the area (= the amount of forest polygons). For this reason, you will maybe notice, that your computer easily deals with some high setting in the one reagon, and almost dies in the other.
      As a rule of thumb you can orient yourself on the map in the download area. The more green you see in the location, the more forests there are and the higher the resource hunger will be. Or some ideas for begin with:

      1. Regions which are light on the hardware
        1. Most of the mediterranean region, because forest density is not so high there. For example a beutyful flight is, to start from Pisa (Italy) and fligh SE along the Mediterranean
        2. The Canary islands – not too much, but very unique vegetation
        3. Ireland
        4. Scotland / UK
        5. Southern Hungary
      2. Regions which are very resource hungry
        1. Most mountin regions, like the Alps (Innsbruck, Zell am See, Bolzano, Aosta, Megeve etc.)
        2. Sweden. This is in some regions incredible. With settings that work in the Alps, you could push your memory over the limit here (so maybe go down with you settings a notch before going there!)
        3. Parts of the Massiv Central in France
    5. And then there are all the other Rendering Options of X-Plane, which you should have an eye on. For example texture resolution has an impact on memory usage. Or the number of objects/roads (although this is not as “bad” in Europe as it is in the USA, where there are much more of them in the scenery). So you can allways think of lowering some other settings, if forests are more important for you.
    6. For Windows users only: because of the memory management of Windows, you normally only get 2 GB of virtual memory adress space fo one process. But in some cases, with all the forests activated, this is not enough and there were reports of crashing X-Planes. Now, since X-Plane 8.60 RC-2 the program is LARGE ADDRESS AWARE, which means that with a certain boot option of your OS you can have X-Plane using up to 3 GB of virtual memory (works only on Windows XP) with the /3GB boot option. You can read here, how to do it. And if you need some technical details about it, you could also the article: Accessing more than 2.0 GB of memory on Windows XP

Finally, here is a screenshot of the highest settings, with which I could run X-Plane forests on my machine (see under 3. , what my hardware and OS is – as of January 2007). This were also the settings I used for the screenshots (well, most of them):
Rendering Options of X-Plane

Rendering Options of X-Plane

Known Issues

The forest overlay is far from perfect, and it has some known issues, which I will maybe address in the future, but I at the moment I wouldn’t say so. Nevertheless, at least in my opinion, the current render is already very enjoyable. So here are the issues:

  • NEW: Problems with native X-Plane 9 forests? Since X-Plane 9 has it’s own forests, I had to include exclusion zones in my scenery. This ensures, that everywhere I provide detailed scenery, the native Global Forests (from the Global Scenery) are suppressed. At the borders, where my data finishes, I had to approximate the exclusions, so sometimes it can happen, that you see some smaller holes. But at least I tried to design my exclusion zones – which were generated programmatically – in way, that they rather overlap a bit with lobal Forests instead of leaving holes. IMPORTANT: the V8 scenery doesn’t has this exclusion zones built in, so it will not blend out Global Forests when used in X-Plane 9. Use the new V9 scenery instead!
  • SOLVED: Forests in water. Since version 8.60 RC-3 of X-Plane, there is an option to tell the sim, that it should never put trees in water. This setting is now in all of the forest definition files, so no prablems there anymore.
  • Forest don’t perfectly match ground textures. This a data consistency problem. The X-Plane team has used less detailed data to generate the texturing of the ground. The CORINE or NLCD data, on which my scenery overlays are based, are much more detailed and accurate, and thus don’t always align with the more “coarse” Global Scenery.
  • SOLVED: Forests on the runways. As of Europe V8.2.1/USA East V8.1.0, this shouldn’t be a problem anymore. Cutting out of airports is now based directly on Global Scenery data. Since V8.2.2 this is further improved.
  • SOLVED/partially: Forests on roads/railroads. As of Europe V8.2.1/USA East V8.1.0, this shouldn’t be a problem anymore. Cutting out of roads/railroads is now based directly on Global Scenery data. But – especially from X-Plane 9 onwards where cities have detailed road grids – there are still some roads which can have trees. this was a development decision, because, if my code had to account for every single, thin road, processing time would have exploded by factor 4-5! Even worse, such detailed cutting would have enlarged the borders of forest polygons extremely, resulting in much more data. Test showed, that some DSF overlays would have had 2-4 times higher size! This would have been much harder for downloads and of course also a big strain on the forest engine in X-Plane.
  • SOLVED: Forests in the outer parts of cities. As of Europe V8.2.2/USA East V8.1.0, this shouldn’t be a problem anymore. With a new algorithm, about 99% of objects are now cut out of the forests.

Modifying – Experimenting

There is a very easy way, to customize the look of the forests to your needs. You “only” have to work with the forest definition files, to change the visuals. And before I describe, what you can/could do, I recommend to read the Forest (.for) File Format Specification from Ben Supnik.

Legal Notice

Scenery overlay files, the textures and forest definition files have benn produced by Andras Fabian (thats me) and Albert Laubi. They are freeware in the sense that you are free to download, copy and redistribute them for personal and non-commerical purposes, provided that the copyright notice is retained in the copy. You are not allowed to charge a fee for these files without the consent of the author other than that to cover the cost of the distribution. If a fee is charged it must be made clear to the purchaser that these files are freeware and that the fee is to cover the distributor’s costs of providing the files. You are not allowed to use these files or parts thereof in a commercial product. In doubt, please conact me.You should also notice, that the data in the scenery is owned by the European Environment Agency (www.eea.europa.eu) For using the original data (which they refer as the DVD) they gave the following notice:
“This DVD has been created by the EEA and the ETC-TE to distribute
Corine Land Cover 2000 and Corine Land cover changes databases. The
information available in this DVD is under copyright of the EEA and
within public domain. Public domain information in this DVD may be used
free of charge, provided the source is acknowledged. The acknowledgement should read: “(c) EEA, Copenhagen, 2005”
For monitoring the use of the I&CLC2000 products the user is requested
to inform EEA in terms of possible applications developed and findings
related to the used products.