World Scenery 2.0

Together with the release of Flightgear 3.0, a new world-wide scenery is now made available!

Flightgear’s world scenery is based on large-scale processing of publicly available and GPL compatible geodata. There is practically no manual intervention involved, which means that the scenery team can’t decide what quality the scenery will have at a certain location, that is only determined by the quality of the available data.

Thanks to the efforts of developers in bringing the processing toolchain up to date, the new official scenery with much better resolution than the previous scenery has now been possible. The new scenery is already available via Terrasync, but it requires a recent version of Flightgear, older versions are not capable of handling the vertex number of the new terrain mesh.

This FlightGear World Scenery was compiled from:
– ViewFinderPanoramas elevation model by Jonathan de Ferranti
– VMap0 Ed.5 worldwide land cover
– CORINE land cover 2006v16 for Europe
– Several custom land cover enhancements
– The latest airports (2013.10), maintained by Robin Peel of X-Plane
– Line data by OpenStreetMap

In general, airport layouts are now improved and updated all over the world, major roads and rivers are drawn to much higher accuracy than previously and the elevation mesh resolution is increased everywhere.


The most stunning improvements are found in Europe, where in addition to the increased resolution of the elevation mesh, also the CORINE database provides high resolution landcover data. This makes the visuals both in mountain regions as well as plains much more applealing. Combined with regional texture schemes and procedural texturing, an almost photo-realistic effect can often be achieved.

Corsica, France seen from above in morning fog (utilizing Mediterranean texture scheme) :

Details of Corsica, France in low-level flight with the F-20:

Fjell lands in Norway (using Scandinavian texture scheme):

Norwegian fjordlands:

Ouside Europe

In the absence of CORINE data, improvements in the landcover rendering are not as dramatic, which leaves flat terrain largely comparable to the previous version of the scenery. However, mountainous regions benefit enormously from the improved elevation mesh resolution. The rendering of light and shade, transition shader effects and snow effects all key on elevation gradients and allow in essence to render the terrain with much more visual detail despite the lack of detailed landcover.

Desert hill chain near Tabas, Iran, seen from the ground (using Middle-East texture scheme and dust shader effect):

As above, seen from the air:

The Grand Canyon, USA (using dust shader effect):

View of the Grand Canyon, USA from high altitude:

Nanga Parbat, Himalaya, Pakistan seen across the Indus valley:

Himalaya north of Nanga Parbat:


Special thanks to the people involved:

John Holden
Olivier Jacq
Vic Marriott
Julien Nguyen
Gijs de Rooy
Christian Schmitt
Martin Spott
James Turner
Markus Metz
Pete Sadrozinski

A preview of features for Flightgear 3.0

Flightgear is constantly under development and as the feature freeze for the next 3.0 release approaches, it is becoming increasingly clear what the next version will have to offer to users:

Scenery 2.0

The next generation scenery has finally arrived!

After long years of waiting, a new version of the world-wide scenery shipped with Flightgear is now being rolled out. This scenery makes use of CORINE data in Europe, utilizes other custom enhancements elsewhere in the world, brings new and improved airport layouts and includes roads and other line data from the Open Street Map project. Especially in the CORINE covered regions, this leads to a much better visual appearance.

Novel water effects

Enjoy watching the shallows around tropical islands in fine weather!

At high quality levels of the water shader, a global water depth map is now used to change the water color in the shallow regions around islands and close to the coast. Especially in the Caribbean, this corresponds to a significant improvement in visual quality. The effect combines with the other variations in water color based on weather and base color due to algae or mud content.

The walker

Now you can get out of your airplane!

The walker project allows to leave an aircraft and explore the scenery on foot. This effectively allows adventure-game like scenarios in Flightgear such as The evil Graveyard where the walker also interacts with the scenery. Combined with the hires procedural terrain texturing options, you can start exploring the scenery from quite a different perspective and walk into your favourite virtual airport bar after a long and exhausting flight.

New airplanes

Enjoy a few new, highly detailed airplanes!

Some recent addition to the list of Flightgear aircraft, the new Boeing 707 (shown above) and the Robin DR400 Dauphin (a single propeller engine plane) impress with impressively detailed modelling of the cockpit, plenty of attention to realistic flight dynamics and especially in the case of the 707 a sometimes frustratingly realistic level of systems modelling.

More complex glass cockpits

Enjoy more realistic instruments!

The canvas 2d rendering technology allows the creation of more realistic glass cockpits with complicated instruments. Shown here is the new PFD and ND of the Boeing-747-400 as an example.

Phototexturing using osgEarth

Explore the scenery textured by aerial imagery!

An experimental implementation of generic phototextured terrain using osgEarth is now on the way and might make it into the 3.0 release. Once enabled, osgEarth renders the terrain scene by building the textured geometry at runtime from raw source imagery and elevation data. The input data can come from a variety of sources including web mapping services or local source data (e.g. geotiff) stored on disk. This feature is runtime-switchable from the default scenery rendering.

Better rendering of fog and haze

We take bad visibility seriously!

For some 3d applications, fog may just be a device to hide the terrain in the distance, but in Flightgear rendering fog and haze is taken quite seriously. The Atmospheric Light Scattering framework now comes with an improved way to render fog patches and variations in fog layer altitude, combined with even more impressive lighting of fog in low sun. You’ll never enjoy bad visibility this much!

And many improvements more…

And that’s not all:

* new regional textures for Scandinavia, Ascension Island and Corsica
* user-controlled moonlight effect for the Atmospheric Light Scattering framework
* added and improved airplanes
* more AI traffic/models

Stay tuned as we fly towards the next release!


FlightGear v2.12.1 Released

November 25, 2013

Update: FlightGear v2.12.1 (a bug fix release) is now available for download!

September 21, 2013 – FlightGear v2.12 is Released!

The FlightGear development team is happy to announce the v2.12 release of FlightGear, the free, open-source flight simulator. This new version contains many exciting new features, enhancements and bug fixes. Highlights in this release include improved usability, continued development of the Canvas rendering toolkit, and improved scenery rendering.

A list of major changes can be found at:

Founded in 1997, FlightGear is developed by a worldwide group of volunteers, brought together by a shared ambition to create the most realistic flight simulator possible that is free to use, modify and distribute. FlightGear is used all over the world by desktop flight simulator enthusiasts, for research in universities and for interactive exhibits in museums.

FlightGear features more than 400 aircraft, a worldwide scenery database, a multi-player environment, detailed sky modelling, a flexible and open aircraft modelling system, varied networking options, multiple display support, a powerful scripting language and an open architecture. Best of all, being open-source, the simulator is owned by the community and everyone is encouraged to contribute.

Download FlightGear v2.12 for free from

FlightGear – Fly Free!

The art of cloud and weather rendering

Author: Thorsten Renk

Advanced Weather

Advanced Weather is one of Flightgear’s two weather-generating systems. It operates based on a (limited) understanding of atmosphere physics – the user selects a weather situation, either from the menu or via specifying a METAR string, and the system simulates the weather from there. For instance, once the system knows how unstable the lowest layer of air is against convection, it automatically decides on the presence of thermals, turbulence, convective cloud number and visual appearance. In this way, generated weather matches cloud types in the different layers based on what would typically also occur in reality for the given weather situation.

The system renders practically all clouds in 3D. To get close to a real sky appearance, it utilizes a large variety of algorithms grouping cloudlets into layers, streaks or undulatus patterns. Combined with the ability to change the weather as a function of position, endless varieties of weather situations appear, and both in the online and offline weather modes, the sky never really looks the same.

Simply select a basic weather scenario and watch the cloud patterns change from high or low altitude!

Clouds and the terrain

Cloud layer placement in level terrain is a simple exercise, but to render weather properly in mountain areas is a challenge. The weather system continually receives information about the terrain surrounding the plane, from which the distribution of wind and turbulence close to the ground as well as the placement pattern of clouds is computed.

Try flying a mountain rescue helicopter in bad weather to see the weather system in action! Or simply go sightseeing in the mountains with a single-engine plane.

Precipitation and turbulence

Precipitation is rendered beneath overdeveloping Congestus and Cumulonimbus clouds as well as beneath layered clouds. Either via a METAR string or on the advanced options configuration tab, the outside temperature can be specified – and precipitation changes from rain into snow accordingly. Also on the configuration tab, the stability of the convective air layer can be determined. Try combining an unstable convective layer with stronger winds, and watch turbulence evolve and rugged clouds with strong vertical development appear, or select a very stable atmosphere and observe well-shaped, large Cumulus clouds evolve. Or try the thunderstorm scenario, and observe large Cumulonimbus clouds tower over the scene.

Using Environment shader effects, it is possible to add a snowline, wet terrain with gleaming puddles or drift ice into the scene – use this for best effect in rainy or snowy weather.

Try setting up a stormy scenario by adjusting the wind, and watch trees sway in the wind. Can you fly a helicopter in 30 kt winds and torrential rainfall?


Advanced Weather is fully interfaced with the Atmospheric Light Scattering rendering framework – which means clouds in low light get differential lighting according to altitude: While cloud bottoms of Cumulonimbus clouds may already be in shadow, cloud tops can still receive light. With the sun behind them, faint clouds glow in bright radiance whereas thick clouds show shadows, making for a beautiful play of light and shade.

The weather configuration tab also contains an air pollution effect – use this to see low light colors of sky and clouds change from clean air to smog.

Try an early morning takeoff before dawn, or flying into the night, and watch the low light illuminating the scene – there’s nothing quite as nice as a sunrise in the mountains.

Advanced Weather for Flightgear – made for pilots who love to watch clouds! All features shown will be available for the next official release!

A preview of novel features for the next release

Flightgear is constantly under development, and the current development version (2.11) contains already a number of interesting features beyond what 2.10 could do – so here is some (incomplete) list of what to expect from the next release:

Novel water effects

As part of the Atmospheric Light Scattering rendering scheme, some novel features have been added to the water shader:

Subtle variations in sea color and surface reflectivity are rendered at high quality, which together with slighly patchy fog improves the visual impression significantly. In addition, an experimental effect generating surf at some coastlines is under active development (coast of Lanai, Hawaii from the EC-135 cockpit).

The environment control allows to a drift ice overlay effect to render winter scenes in cold climate (coastline near Juneau, Alaska).

Improved usability

Flightgear becomes better accessible for the novel user:

A new tooltip system has been added, identifying knobs, gauges and levers for the new user and also indicating their value, thus eliminating the need to zoom to read badly visible instruments. On-screen messages are rendered in a new gnome-like semi-transparent window style. These changes are part of a larger restructuring of the user interface, which standardizes the interaction with cockpit clickspots and adds a more intuitive view mode by right-click/drag as option.


The Rembrandt rendering does shadows best, but this does not mean other frameworks can do nothing:

The balance of direct and indirect light has been re-adjusted to simulate the self-shading of terrain better. In clear weather, shaded surface are now rendered much darker, leading to much improved visuals in low morning or afternoon light (the B-1900D over the French Alps near Grenoble).

Air-air refueling

Fans of realistic air-air refueling will be happy:

The air to air refueling system has been much improved. It now contains a menu to select tanker type, speed and contact radius. Two new tanker planes have been added, and the contact points are now correctly specified, allowing for a much more realistic aerial refueling experience.

Ground texture resolution

Landing somewhere off an airport was never before this nice:

A high resolution shader effect has been added to the procedural terrain rendering of the Atmospheric Light Scattering framework, which renders cm-scale detail resolution. This allows for a much improved low level flight experience and more interesting helicopter operations in the terrain, as there are now visual markers available to gauge distance to the terrain (the EC-135 landing on Lanai shrubland).


The weather system has received a major upgrade. The grouping of sparse clouds into patterns is now much more realistic, replacing simple clusters by visually more interesting undulatus or wavy patterns.

As part of these changes, the rendering of low visibility scenes in Atmospheric Light Scattering has also been made more consistent.


The next version of a well-known aircraft arrives:

The Eurocopter EC-135 is currently undergoing a major overhaul. The FDM is completely revised, leading to a more stable experience in level flight, and the cockpit is done in high-resolution photorealistic texturing (over the French Alps, close to Grenoble).

A large selection of different models is provided, all with different liveries, equipment and slightly altered FDM (over the French Alps, close to Grenoble).


The environment becomes more interactive:

Canvas is a technology to render 2-d information into the scene – it can be used for complicated instruments or a HUD. However, it has now been extended to be applicable to scenery objects as well – this allows for novel features such as airliner docking guidance systems as shown here.

Seasonal effects

Now you don’t only have to fly in summer or winter:

As part of a restructured tree shader, deciduous trees now shed their foliage if they are above the snowline, thus they adapt to the shader-drawn snow effects better. In addition, Atmospheric Light Scattering includes now an experimental season effect (mostly tested for Europe) which allows to simulate the autumn coloring of deciduous forests and pastures.

And many improvements more…

And that’s not all:

* regional textures for Middle East, the UK, Greenland, Indonesia, the arctic sea and Madagascar have been added
* improved aircraft checklists
* better interface between Basic Weather and Atmospheric Light Scattering rendering
* tree movement in the wind
* novel animations, allowing e.g. for more realistic rendering of complex gear motion


Stay tuned as we fly towards the next release!

FlightGear v2.10 Released

February 17, 2013 – FlightGear v2.10 is Released!

The FlightGear development team is happy to announce the v2.10 release of FlightGear, the free, open-source flight simulator. This new version contains many exciting new features, enhancements and bugfixes. Highlights in this release include improved usability, better terrain rendering and a fully scriptable 2D rendering system.

A list of major changes can be found at:

Oscar B., one of our developers made a movie to highlight some of the new features in v2.10

LukeaFG has also made an excellent promo video showing some of the new v2.10 features.

Founded in 1997, FlightGear is developed by a worldwide group of volunteers, brought together by a shared ambition to create the most realistic flight simulator possible that is free to use, modify and distribute. FlightGear is used all over the world by desktop flight simulator enthusiasts, for research in universities and for interactive exhibits in museums.

FlightGear features more than 400 aircraft, a worldwide scenery database, a multi-player environment, detailed sky modelling, a flexible and open aircraft modelling system, varied networking options, multiple display support, a powerful scripting language and an open architecture. Best of all, being open-source, the simulator is owned by the community and everyone is encouraged to contribute.

Download FlightGear v2.10 for free from

FlightGear – Fly Free!

FlightGear v2.10 Release Candidates

February, 17, 2013: FlightGear v2.10 is official released.  Please proceed to the download page and download the full official release!  All the files shown here are old news.  Please move along, nothing more to see here. 🙂

This is the place to find the v2.10.0 release candidates as they become available.  We would really love for everyone to download these “test” releases and give them a try.  The target date for the official FlightGear v2.10.0 release is February 17.

Download FlightGear v2.10 Release Candidates:

(Release candidates can be updated frequently and the mirror system can take some time to update, so if a download link doesn’t work, please try another mirror.  If none of the mirrors work, try refreshing this page to get a new set of mirror suggestions.  Or try again in an hour or two.)

Download v2.10 Aircraft:

  • Download the newest versions of all the aircraft at the v2.10 Aircraft Download Page.  These are also have “release candidate” status and could be subject to changes before the official release.

Download v2.10 Scenery:

  • The FlightGear scenery is continuously being improved.  The newest available scenery works with both v2.8 and v2.10.  We update the scenery packages with any new models or changes every few weeks.  Get the latest scenery through the usual means from the Scenery Download Page.

Source Code

What’s New?

Comments or Questions?

  • If you have comments or questions regarding the release candidates, please go to the FlightGear forum.


Fly Hawaii!

Author: Thorsten Renk

Destination Hawaii

One of the first places available as hires scenery in Flightgear, and also among the first places to receive a dedicated regional texture scheme, the island chain of Hawaii is a very spectacular destination in the Flightgear world. It offers a compelling variety of terrain from dry and barren lava plains to lush tropical rainforest, from the gentle fertile plains to rugged mountains and steep cliffs towering over the sea and from the densely populated island of Oahu to uninhabited Kaho’olawe.

Flying Hawaii can be easy or challenging – there are busy international airports and lone airstrips in remote locations, the altitude of the terrain ranges from sea level all the way up to Mauna Kea towering at 13,796 ft and steep gorges cut into the lava cliffs allow for tricky helicopter excursions.

Currently the scenery is only available via TerraSync and not by direct download from the website, presumably this will change with the next release of world scenery. While the release preparations for Flightgear 2.10 are underway, this article provides a first glimpse into some stunning new features which are currently being developed for the 3.0 release in summer 2013 – high resolution terrain texturing for closeup scenes.

Aeronautical charts for the whole of Hawaii are available online at, see for instance here for all charts relevant for Honolulu International Airport.

Hawaii ‘Big Island’

With a total area of 4,028 square miles, Hawaii is by far the biggest island of the archipelago, exceeding the size of all other islands taken together. It is also the youngest of all islands, dominated by the gentle rising cones of the five massive shield volcanoes Kohala, Mauna Kea, Hualalai, Mauna Loa and Kilauea, with the last two still being active.

The central part of the island is occupied by the twin cones of Mauna Kea (foreground) and Mauna Loa (background) which both reach above 13,000 ft and consists of extended lava fields, while the coastal region is somewhat more fertile.

The first destination reached however when arriving from the Honolulu region is Upolu Point, a region of eroded volcanic rock and spectacular gorges.

A flight to Hilo, the main city of the island, can pass between the two major shield volcanoes and requires a climb from sea level to more than 7,000 ft, which requires some adjustment of the mixture in a single-engine propeller plane. The climb to the pass is mainly above arid grasslands.

At higher altitudes, the spectacular lava fields of Mauna Loa dominate the scene.

Here is yet another view on Mauna Kea from the pass – often the volcanoes reach above the cloud layer.

Seen from the pass, Hilo seems close, but the slope of the terrain is so gentle that it is very easy to underestimate the true distance. Towards the coast, forests and fertile ground dominate the scene again.


Maui is perhaps the island with the most diverse terrain. Its eastern part is dominated by the mighty cone of Haleakala, reaching just above 10,000 ft. The middle part is a fertile valley, whereas the western part features the rugged West Maui Mountains, which are considerably lower than Haleakala, but certainly make up for that with steep cliffs and deeply cut valleys.

Since the prevailing winds come from the northern side, air rises on the flanks of Haleakala, leading to fertile and overgrown northern slopes, whereas the southern slopes of Haleakala look completely different and show rather different weather.

Flightgear’s Advanced Weather is actually capable of simulating the resulting distribution of clouds from this effect – in fact, Haleakala has been an inportant test case in the development of the weather system.

Closely grouped in the vicinity of Maui are also the islands Lanai, Molokai and Kaho’olawe, easy to see in clear weather, thus Maui is an ideal starting point for island-hopping adventures.

Approaching from east, the scenery is dominated by Haleakala, here the more arid southern slopes are seen.

Maui is substantially older than Hawaii island, and so the volcano has started to erode quite significantly when compared to Mauna Loa – as a result, the fertile land extends much higher up. Haleakala crater however remains a rather impressive sight.

When approaching from the west, the cliffs and gorges of the West Maui Mountains are the first feature to become apparent.

On a clear day, the surrounding islands (here Molokai in the background) can clearly be seen:

The West Maui Mountains themselves contain quite some impressive sights – it is especially worthwhile to explore the various canyons and cliffs with a helicopter.

Yet another flyby view from the F-14b RIO position on the West Maui Mountains:


Going west, the geological age of the island chain increases, and thus terrain features become more gentle as the volcanic rock erodes and changes into fertile soil. The island of Oahu is where the majority of the Hawaiian population lives and where the capital Honolulu is located. This is also where Honolulu International Airport, the most busy of all Hawaiian airports is found, and the home of famous sights as Pearl Harbour. Honolulu was envisioned as an emergency landing site for the space shuttle, and in fact the ‘reef runway’ (shared, as the rest of the airfield, with Hickam Air Force Base) used to be designated for this purpose.

Oahu stretches between two mountain ridges, which rise up to an elevation of just over 4000 ft. Here is a view of the island from the west.

Central Oahu is flat and largely in agricultural use. In the background, Honolulu and Pearl Harbour can be seen.

One of the most scenic spots on the island is Kailua beach on the north-eastern coast, offering a spectacular constrast of steep cliffs, long beaches and lush tropical vegetation.

The hires ground texturing scheme for Oahu has been carefully designed to display the contrast between lush vegetation and the red volcanic soil.

The other islands – Lanai, Molokai, Kauai, Kaho’Olawe and Niihau

Lanai is a fairly arid and sparsely populated island south-west of Maui with a single airport. It is dominated by a single mountain ridge reaching just above 3000 ft, with some valleys carved by erosion.

Molokai is, like Maui, a fairly diverse island – its eastern part consists of steep and towering cliffs whereas its western part is mostly flat and gentle landscape. Kalaupapa airport (PHLU) is built on a peninsula just beneath the cliff faces.

Kaho’Olawe is a small, uninhabited island. It has no airport and can only be reached by helicopter.

Its surface is mostly composed of arid stretches and lava fields.

Kauai, the garden island, is one of the nicest bits of scenery in the Hawaiian islands. It features the spectacular Na’Pali coast and Waimea Canyon.

Sadly, the scenery in Flightgear is currently a bit of a let-down – the terrain shows some errors in Kauai, and neither the Na’Pali coast nor Waimea come anywhere close to the originals.

Here is a scene close to Hanalei:

Finally, the island of Niihau is not part of the high resolution scenery package, and thus not really worth visiting.

Some Hawaiian airports

Hilo International Airport (PHTO) is located on the eastern side of Hawaii island at the coast – in a vert scenic location close to the town of Hilo. It is one of the two major airports of the archipelago and with a runway length of 9,800 ft large enough to admit essentially all airplanes.

Kona International Airport (PHKO) is located in the lava fields at the western coast of Hawaii island. Three million pounds of dynamite have been used to flatten the lava flow on which it was constructed. It offers a single 11,000 ft runway which is second in length only to Honolulu International Airport.

Waimea-Kohala Airport (PHMU) is a not very busy public airfield at 2,600 ft altitude in the western drylands of Hawaii island. It offers a single 5,197 ft runway.

Princeville: (HI01) is a small private airport close to Hanalei on the garden island Kauai. It is only suitable for smaller aircraft.

Lihue: (PHLI) is the main airport of Kauai. It has mainly connections to Honolulu, but also some long-distance traffic to the US mainland.

12 Days of Flight Tips (Season 2)

Last year, Oscar (youtube user: osjcag) created a series of short “howto” movies called the 12 Days of FlightGear Tips.  This year he is producing Season #2!  Each day he releases a new tip in honor of the twelve days of Christmas. Make sure you check back each day for the new tip!  Even “seasoned” FlightGear pilots may pick up a new trick or two.  Enjoy!

Terrain Texturing

Author: Thorsten Renk

Regional and procedural texturing

It’s perhaps not a big secret that the default Flightgear World Scenery does not look stunning everywhere in the world. Yet, with regional texturing in Flightgear 2.8 and easy to configure procedural texturing in the current development version 2.9, two techniques have arrived which have the potential to rapidly change this. But precisely what are these techniques?

Short of addons such as fgphotoscenery, Flightgear has never used aerial photographs for texturing. Instead, the terrain is described in terms of landclasses, and each landclass has an associated texture. Up to 2.8, these texture definitions were the same all over the world, Yet in reality, this is not true – cities in the US for instance tend to be organized in rectangular grid patterns which are completely uncommon in Europe, Irrigated crops in Asia are most likely rice terraces, whereas rice terraces are not a common sight in the US Mid-West. Regional texturing allows to define texturing schemes for specified geographical regions and allow to overcome these problems – European cities can now defined to look different from US cities.

Procedural texturing is an even more powerful technique. In the default rendering scheme, the terrain of a certain landclass is painted with a pre-defined texture, then the light is computed and this is what we see on the screen. Procedural texturing does not use a pre-defined texture, but computes the texture as part of the rendering process. This powerful technique allows textures to be sensitive to the environment and hence simulate wet or dusty terrain, to create the actual texture as a mixure of various overlay textures which change dependent on how steep the terrain is or to add snow cover with any density on the fly. Procedural texturing has been part of the shader effects in Flightgear 2.8, for instance in terms of the wind-dependent wave patterns of water, or the snowline settings, but in 2.9 it gained many additional options and most important is configurable without any knowledge of OpenGL rendering by just a few lines of xml code.

Procedural texturing is best illustrated pictorially – here is a scene (China Lake Naval Air Weapons Station (KNID), California) in default texturing. The visible terrain is mostly shrubland, and there is a pronounced tiling effect – the texture pattern is seen to repeat in the scene, leading to regular structures which become even more prominent from higher altitude.

The same scene in procedural texturing looks much more appealing – the random mixture of different base texture removes the tiling for good, and a thin dust effect creates the impression of dry terrain as appropriate for the near-desert location.

Unfortunately, procedural texturing does not come for free – computing textures on the fly creates a significant drain on framerate, thus procedural texturing is only suitable for modern graphics cards.

The structure of Flightgear Scenery

The combination of regional and procedural texturing is extremely powerful and allows to make dramatic improvements to the world scenery at the simple expense of few lines of xml code. Let’s look at an example location:

Canaima National Park in Venezuela is one of the world’s most fascinating mountain regions with table-mountains like Auyantepui towering over jungle terrain, featuring the world’s tallest waterfall, Angel Falls (3,287 ft). The scenery offers steep near-vertical cliffs hundreds of meters high, rugged and inaccessible plateaus atop the table mountains and lush tropical forest with winding reivers at their feet. The best place to access the park is Canaima airport (SVCN).

Yet, in the Flightgear default rendering scheme, Auyantepui is shown like this:

There is… something wrong here. In order to understand what goes wrong, let’s take a short look at the structure of the Flightgear scenery.

The basic ingredient of the scenery is the terrain mesh, containing the elevation data for all mesh points and the information what landclass the terrain between grid points is. The terrain mesh is created by a tool called TerraGear from public geodata. The output of this stage contains the altitude information of the terrain, and for instance the information that the terrain represents tropical forest (the so-called ‘landclass’).

Upon loading the terrain once it is used by Flightgear, the landclass is associated with a texture. At the same time, random objects such as buildings or trees are created and placed upon the terrain mesh where appropriate. Thus, the tropical forest landclass would at this step be associated with a forest texture and be populated with a large number of trees. At this stage, also shader effects are associated with a particular landclass, for instance water receives a reflection effect, whereas urban terrain may receive the urban shader effect.

In the last step, static (unique and shared) objects are added to the scene. These are objects which appear always at a given location, for instance airport terminals or special landmarks, and they are found in the Flightgear Scenery Database.

Armed with this knowledge, let’s analyze the above scene to find out what goes wrong: We can see that large parts of the table mountain get an agricultural texture. Visiting the scene with the ufo and using ctrl + alt + click (only in 2.9) on the offending terrain reveals that the mesh is here classified as ‘DryCrop’. This isn’t completely unreasonable, as the top of the table mountain is a rather barren grassland – but DryCrop becomes automatically associated with Europen-style agriculture textures – which look just plain silly in a place which in reality is utterly inaccessible, despite the valiant effort of the shader effect to change the agriculture to brown earth on steep slopes. Similarly, the nearby tropical forest is classified as ‘EvergreenForest’ (which is technically correct) – but EvergreenForest is associated with needle forest textures and needle trees.

Editing scenery texturing

There are various possibilities how this could be addressed. For instance, using TerraGear the landclasses in the scenery could be changed to something closer to reality. But to do this requires some learning, TerraGear is not a trivial tool. In this case, it is also unnecessary: The basic elevation mesh is in good order, the landclasses are not unreasonable, just the way textures and random objects are assigned to them is not working, and thus we need to change this.

The mapping of landclasses to textures and various other properties is controlled by a file called materials.xml. The regionalized version of it is found under $FGRoot/Materials/regions/materials.xml. In this file, for each landclass, a block of definitions exists. The idea is then to just copy the block for ‘DryCrop’ and edit the copy to contain an alternative definition valid for a particular geographical region, then change the texture to something more suitable. Plenty of nice textures already are in $FGRoot/Textures/Terrain/ and $FGRoot/Textures.high/Terrain/, so usually we don’t even need a new texture. While we’re at it, we might as well add two more lines to the etxture declaration specifying the overlay texture for procedural texturing. And that’s all it takes – next is EvergreenForest – we repeat the procedure and in addition change the tree texture from evergreen needle trees to tropical trees.

After just about an hour of editing materials.xml (the whole procedure is described in detail here), Canaima National Park looks like this:

Much better – isn’t it? Now all that’s missing is Angel Falls – we’re going to need a static model for this. The Particle System of Flightgear is going to be our friend here…

Canaima Sightseeing

After adding the model of Angel Falls using the ufo, Canaima National Park is ready for a sightseeing Flight (Flightgear 2.9 users can already enjoy it like this!) – once the landclass assignment is okay, procedural texturing takes care of the rest:

Steep cliffs and sheer drops flying over Auyantepui enroute to Angel Falls:

Table mountain tops reaching above the clouds:

Angel Falls seen from high altitude:

The barren top plateau of Auyantepui:

Tropical rainforest on return to Canaima airport:

Don’t wait for someone else to fix the terrain you want to explore – it’s easy, the tools are there and in many cases it’s more work to create a single model of a building than to make terrain texturing in a vast region look good!