TerraLand Elevation & Imagery Global Coverage Resolutions

Elevation Data Resolution

The World Elevation data resolutions are ranging from over 30 meters in most of the Earth areas to approximately 3 meters in some limited areas.

In Depth:

• The AHN Netherlands (AHN2) 3 meters* DTM covers entire Netherlands.
• The Geoland 10 meters DTM covers entire Austria.
• The Geodatastyrelsen DTM (approx. 3 meters* and 10 meters) dataset covers entire Denmark.
• The National Land Survey of Finland 3 meters* and 10 meters DTM covers partial areas of Finland and entire Finland respectively.
• The Norwegian Mapping Authority 10 m DTM covers the entire area of Norway.
• The Ordnance Survey’s OS Terrain 50 (50 meters) dataset covers Great Britain.
• The FEMA LiDAR DTM (approx. 3 meters) covers partial areas of the conterminous United States.
• The National Elevation Dataset (NED) 1/9 arc second (approx. 3 meters) dataset covers areas of the conterminous United States and small areas of Alaska.
• The National Elevation Dataset (NED) 1/3 arc second (approx. 10 meters) dataset covers the conterminous United States, Hawaii, partial Alaska, and Territorial Islands of the United States.
• The National Elevation Dataset (NED) 1 arc second (approx. 31 meters) dataset covers the conterminous United States, Hawaii, partial Alaska, Puerto Rico, Territorial Islands of the United States, Canada and Mexico.
• The National Elevation Dataset (NED) 2 arc second (approx. 62 meters) dataset covers the state of Alaska.
• The Shuttle Radar Topography Mission (SRTM) 1 arc second (approx. 31 meters) dataset from NASA covers all land areas between 60 degrees north and 56 degrees south except Australia (which is covered by DEM-S from Geoscience Australia).
• The Shuttle Radar Topography Mission (SRTM) 1 arc second (approx. 31 meters) DEM-S dataset from Geoscience Australia covers Australia.
• The Shuttle Radar Topography Mission (SRTM) 3 arc second (approx. 93 meters) dataset covers all land areas between 60 degrees north and 56 degrees south.
• The EarthEnv-DEM90 3 arc second (approx. 93 meters) dataset covers approx. 90% of globe.
• Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) 7.5, 15 and 30 arc second (approx. 232, 464 and 928 meters) datasets cover global land areas.
• General Bathymetric Chart of the Oceans (GEBCO)** 30 arc second (approx. 928 meters) dataset covers the entire globe.

So, in most cases you are going to have the source data ranging from 30 to 10 meters resolution and in worst case scenarios it’s 90 meters in resolution.

But as mentioned earlier, TerraLand can dynamically resample the source data to user specified resolutions and have higher resolution extracted from the original data if needed. Needs extra Smoothness operation though.

Note: Resampling the data to higher resolutions doesn’t mean that there will be extra details of terrain surface which doesn’t exist in original data but just provides flexibility in resolutions and maps existing height values to a higher dataset for later enhancement features on heightmap.

Satellite Imagery Data Resolution

World Imagery provides one meter or better satellite and aerial imagery in many parts of the world and lower resolution satellite imagery worldwide.

• 15m TerraColor imagery at small and mid-scales (~1:591M down to ~1:72k) and 2.5m SPOT Imagery (~1:288k to ~1:72k) for the world
• 0.3m resolution imagery in the continental United States and parts of Western Europe from DigitalGlobe
• Additional DigitalGlobe sub-meter imagery is featured in many parts of the world, with concentrations in South America, Eastern Europe, India, Japan, the Middle East and Northern Africa, Southern Africa, Australia, and New Zealand. Sub-meter Pléiades imagery is available in select urban areas globally
• In the United States, 1 meter resolution NAIP 2013 through 2015 imagery is available (~1:36k down to ~1:4k) across 47 states
• In other parts of the world 1 meter resolution imagery is available from GeoEye IKONOS, Getmapping, AeroGRID, IGN Spain, and IGP Portugal
• Additionally, imagery at different resolutions has been contributed by the GIS User Community. In select communities, very high resolution imagery (0.07m) is available down to ~1:280 scale

Source: https://forum.unity.com/threads/terraland-2-high-quality-photo-realistic-terrains-from-real-world-gis-data.377858/#post-2478547