AW3D30

From OpenStreetMap Wiki
Jump to navigation Jump to search
AW3D30 - Other languages

The ALOS Global Digital Surface Model "ALOS World 3D - 30m" (AW3D30) is the dataset with a horizontal resolution of approximately 30-meter mesh (1 arcsec), provided by Japan Aerospace Exploration Agency (JAXA) free of charge. The dataset has been compiled with images acquired by the Advanced Land Observing Satellite "DAICHI" (ALOS).

The dataset is published based on the commercial DSM dataset (5-meter mesh version) of the "World 3D Topographic Data", which is the most precise global-scale elevation data at this time, and its elevation precision is also at a world-leading level as a 30-meter mesh version. The positive difference in detail level is clearly visible even in simple visual comparison with SRTM 1-arcsecond data with similar pixel size.

Warning: this surface model, as well as many others, including SRTM, has significant feature: it does not reflect a shape of a ground surface but reflects an envelope surface, "draping" over buildings, tree tops and other natural and man-made objects.

For coverage details, see official interactive map (white and black areas are masked as invalid due to cloud or snow/ice cover).

For detailed quality review, read this article by Christoph Hormann.

Data format

  • Resolution: 1 arcsec (approx. 30m mesh) containing 1° lat/long tile.
  • Height accuracy: 5 meters as standard deviation (1σ)

Composition:

  • DSM (Height above sea level, signed 16bit GeoTIFF) The calculated elevation value by average (AVE) and median (MED) when resampling from 5-meter mesh version. The nearest neighbor (NN) is considered in next version)
  • Mask information file (8bit GeoTIFF, DN=0: Valid; 1: Clouds, snow and ice (invalid); 2: Land water and low correlation (valid); and 3: Sea)
  • Stacked number file (8bit GeoTIFF, DN=number of stacking)
  • Quality assurance Information (ASCII text, add information for 1 arcsec product to original 5-m mesh DSM information)
  • Header file (ASCII text)

Header file format definition. Full product information (in Japanese).

Obtaining data

To download AW3D30 data, it's required to fill the registration form. A confirmation letter will be sent to email, submitted with this form. After confirming your registration, you will receive another email with login and password.

After completing registration, you can proceed to download page. First, you have to select 30°×30° region of global coverage map, then - 5°×5° region. 5°×5° regions are downloadable, but if you need smaller 1°×1° coverage, you can proceed to the next page by selecting one of the sub-cells on the map.

Data package has *.tar.gz format. Downloaded 5°×5° region package contains a number of separate 1°×1° fragments, named accordingly to coverage coordinates .

License

Original terms of use (Updated on April 1, 2016):

This dataset is available to use with no charge under the following conditions.

When the user provide or publish the products and services to a third party using this dataset, it is necessary to display that the original data is provided by JAXA.

You are kindly requested to show the copyright (© JAXA) and the source of data When you publish the fruits using this dataset.

JAXA does not guarantee the quality and reliability of this dataset and JAXA assume no responsibility whatsoever for any direct or indirect damage and loss caused by use of this dataset. Also, JAXA will not be responsible for any damages of users due to changing, deleting or terminating the provision of this dataset.

It means, that AW3D30 can not be used to update OSM data directly, since it explicitly requires to display attribution information (unlike some other sources, in which cases it's okay to have them mentioned on Contributors page). But third-party services can use it for relief shading or isohypse contour generation just like some of them already doing with SRTM data (see warning about the nature of surface model above).

See also

Retrieved from "https://wiki.openstreetmap.org/w/index.php?title=AW3D30&oldid=2001129"