About the New Global Scenery

    Revision History
  • 11-17-05

    Initial Draft

Coverage and Extent

The new global scenery render covers the world from 54 degrees south to 60 degrees north inclusive. This is the same area as the SRTM2 dataset. There should be a DSF for any file that has SRTM data and is not totally filled with water.

The new global scenery comes on 7 dual-layer DVDs, divided by continent for easy installation. The installer lets you select sub-areas to install; the whole package is approximately 54 GB.

A note on framerate: you will almost certainly have to turn your rendering settings down a notch when you use the global scenery. This may feel like a 'step backward' (I used to run with 'insane objects' and 'extreme res' now I only get 'tons' and 'very high'), but it's not! Basically we now use a larger number of textures, more triangles in the mesh, in some cases more objects, and more quads in the roads than we used to. If you are using the same machine, you must turn down the settings to compensate for this increase in detail. In other words, the global scenery spends your system resources in different ways. By using more textures at a lower resolution we can create a more realistic environment.

We do not expect you to be able to run this scenery on 'extreme' res, 'insane objects, etc. unless you have a very powerful computer. (This is why they are named 'extreme' and 'insane'!!) Graphics cards double in power every six months, computers every two years. We have to create scenery that will look good for users with slower computers and great for users with faster ones. This is what we have tried to do with this render; we hope it will look good even with objects and roads off and 'high' resolution. If we set the maximum settings to work on an older computer, then users with new computers would be able to run at 200 fps but would not be getting all of the detail their machines were capable of. So this scenery has been designed to run on a range of settings.

Most of the picturse I have posted are at 'extreme' resolution and 'insane' objects; my poor computer with a Radeon 9600XT can't display the scenery very fast like this. It is definitely worth experimenting iwth the settings. In particular the "world detail level" setting makes a huge difference in the performance of the scenery. You may be able to turn the object density up by turning this down. (This is similar to autogen-distance vs autogen-level in X-Plane 7; the world detail level is like autogen distance, and the object density is like autogen-level.)

New Features and Technology

The new global render involves a number of major upgrades from our last set of DSFs, the US render:

Terrain

  • New data sources; the whole set is rendered via the SRMT2 data set - this is the SRTM DEMs with flattened water. We then fill in holes in the SRTM using NED data for the US and GTOPO30 for the world. Cities utilize NED data to filter out sky-scraper artifacts.
  • New rule-set based terrain textures. Our artists created 700 MB of new terrain textures, as well as a 600-rule control file to determine where they are placed.
  • A new border blending system produces dithered transitions between terrain files; no more sharp borders.
  • A new mesh algorithm produces more accurate terrain shapes using less triangles.
  • A synchronization algorithm matches terrain across DSF boundaries for smooth tiling. (See bugs for more info.)
  • City textures are photo based - they look like cities even if you cannot run with objects. They also come with night lighting maps.

Water

  • The coastlines are based on the SWBD (SRTM Water Body Data) coastline dataset as well as VMAP0 vectors. (US data comes from the TIGER 2002 dataset.) This provides more accurate coastlines than just VMAP0. In some cases we had to blend SWBD and VMAP0 because SWBD sometimes misses rivers.
  • Some rivers were added to appropriate environments by hydrological analysis of the terrain.
  • Water contains some sea-lake water codes; right now the sim can't do much with this but this will allow us to tune the look of water in the future.
  • We render beach overlays onto most land/water transitions, using a ruleset to determine what beach belongs to a given location. A new .bch file provides the graphics and can be customized.
  • We use SRTM2 data, which provides flat water, as well as our own flattening algorithm.

Airports

  • The airport area is now rendered in a special terrain to isolate it from the rest of the scenery.
  • We calculate the airport area's extent and make sure to fill in water (for airports that are right on the water when the coastline data is inaccurate) and we make sure no objects are placed on the airport premisis
  • Airports are slope-controlled; with 820 it should be possible to turn on "sloped runways" and fly with the new global scenery.

Roads

  • Roads now work in 3-d: where two roads cross we render an overpass depending on the road type and intercept angle.
  • We have bridge road types for suspension bridgse, arch bridges, and other types.
  • Roads are carefully tessolated over the terrain mesh to 'hug' the terrain instead of flying over it.

Buildings

  • Objects are now placed according to terrain type; this means they should only occur in cities and not over airports.
  • Objects are placed with height control parameters, so the scenery will not be too "tall" outside downtown areas.
  • Multiple buildings are grouped into single objects for performance.
  • Building placement takes slope into consideration to limit artifacts.
  • Buildings and antennas are properly matched in height to the real-world obstacles.
  • US objects are freshly reimported from the FAA obstacle database.
  • Tall buildings and other FAA obstacles are prioritized in the file so that they are visible even on the lowest object settings.

Limitations

There are some definite limitations to the global scenery; here are some of the big ones...

  • Global coastline inaccuracies. I am not sure how many there are; the SWBD dataset is a great imrpovement for coastline data but definitely not perfect, and the merging of this dataset with VMAP0 causes problems too. So there may be some strange coastlines in areas where the source SWBD data was not good.
  • No coverage past 60N. This is because we only created scenery for SRTM elevation data. There's a lot of great flying beyond 60N and we do want to create scenery for these areas. We chose not to go past 60N to limit the scope of the project; each time we get a new elevation dataset we must retune our algorithms extensively. Adding areas beyond 60N would have delayed shipment by months, so we chose to release what we already have first.
  • Non-US roads. The dataset for non-US roads (VMAP0) is very inaccurate - road location can be wrong by up to 1 km. For this reason you will see European roads climbing up mountains, etc. We have not attempted to move the roads to the rihgt place; unlike rivers, there is no "iron law" for where the road should be.
  • Object Artwork. The DVDs are shipping with the first revision of the object library for the US and no library for non-US. This means that you will not have objects outside the US initially. The objects are in the DSF files, so once we have a global library of OBJ files, we will release it as part of the next sim patch and you will be able to quickly download it for free and then see objects everywehre.
  • While we were planning 3-d forests, this feature did not make it into the render; the technology was not ready in time. We are still working on this and the sim itself will support 3-d forests; the global DSFs do not have any 3-d forests thouhg.