Scenery System Frequently Asked Questions
From X-Plane Wiki
Why do all parts of the global scenery not look equally good?
There are roughly three levels of quality in the scenery. The continental US is most detailed due to SRTM data and detailed road maps. The entire world from 54 degrees south to 60 degrees north is somewhat detailed, thanks to SRTM data, but the roads are not as detailed. Parts of the world not covered by the SRTM data (where the SRTM data is corrupted) are very inaccurate due to a lack of high quality elevation data and high quality vectors.
Also, the accuracy of the data we use varies; sometimes it is very good and sometimes there are errors. You may get lucky and find your home town looks perfect, or you may find huge errors. While we try to make the global scenery as good as we can, we cannot go through the entire world and hand-correct errors. It will be possible to use our tools to make custom scenery that represents small areas with a high degree of accuracy and detail.
What is a DSF file?
DSF stands for Distribution Scenery File format. DSF is the file format for the X-Plane 8 and 9 native scenery. ENV is the file format for version 7 and older scenery.
What is the resolution of the terrain mesh in version 8?
The terrain mesh in version 8 can be variable resolution; there may be more mesh points in some areas and less in others. There is no upper limit on the resolution for the mesh. The default scenery is created from 90 meter DEMs and usually has a maximum density of 90 meters. The default scenery usually has approximately 100,000 triangles per square degree, but this does vary.
Does the scenery system support custom objects?
Yes, absolutely! You might almost say that the scenery system only supports custom objects. In X-Plane 8 and 9, there are no objects built into X-Plane; every object comes from an OBJ file somewhere. Objects can either be in a library or directly in a custom scenery package. The default scenery uses only objects from libraries, but a DSF file can use objects from its own scenery package as well. You can have hundreds of thousands of objects hand-placed in a DSF file.
Can the scenery system create photorealistic scenery?
Yes. While the default scenery is not photorealistic (it is based on classes of land, road networks, and individually placed objects for buildings), it is possible to use aerial or satellite photographs to create scenery. For more information, see the Airport Customization tutorial.
What happened to AutoGen? Is Autogen coming back?
The version 8/9 scenery system does not support auto-gen as we know it from X-Plane 7. In X-Plane 8 and 9, objects that correspond to a given terrain type (apartments or shops in a city, farm houses on a field, etc.) are each individually placed in the DSF files by the scenery-generator tool. This allows objects to be placed using a very complex algorithm that would be too slow to run inside X-Plane while flying. For this reason, objects cannot be placed automatically based on terrain. X-Plane can, however, place objects along vector roads--powerline towers are placed this way. This is similar to autogen.
Can X-Plane 8 and 9 read version 7 scenery?
Yes. X-Plane 8/9 will load X-Plane 7 custom scenery packages without any modification. Scenery packages that require modifying the Resources folder may not work without modification. However, X-Plane 8/9 do not support autogen, so version 7 scenery will look sparse.
What happened to the vector rivers in my custom scenery?
X-Plane 7 featured rivers as textured line segments; the X-Plane 8/9 rendering engine draws all water, no matter how narrow, as full polygonal waterbodies. The upside of this decision is that a seaplane can correctly land on anything that looks wet in X-Plane 8 and 9. The downside is that we cannot draw X-Plane 7 vector rivers in versions 8 and 9.
General Scenery Development
What is Photo-Realistic Scenery?
Photo-Realistic scenery is scenery based primarily on high resolution aerial or satelite photographs. Essentially you are flying over a picture of what the area looks like in real life.
Probably the greatest strength of photo-realistic scenery is that while in flight, it looks almost exactly like what you see out the window of a real aircraft. However, it has some limitations too: because it is based on photographs, shadows do not change with the time of day, season, or weather, and when you fly low to the ground, it becomes clear that you are not flying over real buildings, but pictures of buildings.
Photo-realistic add-ons are available for X-Plane. The global scenery is not created using this technique for two reasons: there is not a good source for global high resolution photos that we could use, and also the scenery (at 16 meters per pixel) would potentially take up 2340 GB - that's 260 DVDs.
It is possible to make photo-realistic scenery with our new scenery tools (see the the Airport Customization tutorial). It is also possible to combine photo-realistic scenery with other scenery techniques. For example, you can use land classes where photos are not available, and place buildings over their images in the scenery for a 3-D look in cities.
What is land class scenery?
Landclass scenery is scenery based on catagories of land. The world is broken down into areas with catagories such as forests, cities, farms, etc. and then the terrain is textured based on these catagories.
Landclass scenery can cover a large area with only a few image files (one for each land class), but a large area of a single land class can look repetitive (for example an area of repeating farms). More textures can be used to hide the repetitions.
The global scenery is to some extent land-class scenery.
What is the SRTM?
SRTM is the Space Shuttle Radar-Topography Mission, a joint project between NASA and the NGA to collect high quality global elevation data. The SRTM is one of the best free, public domain sources of elevation data available right now. SRTM data has a resolution of 90 meters worldwide and 30 meters in the US. The SRTM data covers a latitude band from 54S to 60N.
What is the Maximum Resolution of a Base Mesh?
X-Plane does not have maximum resolutions; the file formats are variable resolution. Mesh resolution is limited by memory; you could support a very high resolution over a small area.
The current tools are limited to 90 meters horizontally and 1 meter vertically; these limitations could be removed or adjusted fairly easily in the tool source code, and may be improved in the future.
What is the Maximum Image Resolution?
X-Plane does not have a maximum image resolution; the scale of images is decided by the metadata files that go with terrain imagery. The constraining factors are memory (VRAM and virtual memory) and performance.
Individual texture images can be a maximum of 2048x2048 pixels, but you can use a theoretical limit of 32768 separate images for about 2-4 pixels per meter. In practice, system resource constraints kick in first.