ALOS/PRISM AW3D30

The ALOS/PRISM AW30D30 is a global digital elevation model (DEM) with 30 m resolution, generated based on optical photogrammetry with the PRISM sensor. PRISM is a panchromatic stereo mapping sensor operated onboard Japan Aerospace Exploration Agency (JAXA)’s ALOS “DAICHI” satellite between 2006 and 2011. PRISM consisted of three radiometers viewing forward, nadir and backwards with 35 km swath-width, producing three sets of stereoscopic images. JAXA has been developing a precise digital 3D map using about 3 million PRISM stereo scenes, resulting into an Earth Digital Surface Model (DSM) with near-global coverage and ortho-rectified nadir-look image of PRISM. As a commercial product, AW3D (ALOS World 3D) offers up to 0.15 arc-second (5 m) resolution within 80° North and 80° South latitude range. For non-commercial purposes, the resolution level of 1 arc-sec (30 m) is publicly available as JAXA product AW3D30. This data set is distributed in terms of 1° x 1° geographic latitude and longitude tiles, shown here . AW3D30 was developed based on AW3D, through down-sampling of the 0.15 arc-sec resolution down to 1 arc-sec of AW3D. In its newest version of v1.1, JAXA has filled existing voids (no-data areas) between 60° North and 60° South with auxiliary DEMs (e.g. NLMI DEM of Japan, SRTM v3 and PRISM DSM) using the Delta Surface Fill method to ensure smooth continuity of topography at the boundaries of the voids. In high latitudes, no-data areas are still present. A single AW3D30 1 degree x 1 degree tile is of about 28 MB size (compressed tar.gz). For each tile 5 files are available, these are the elevation data (digital surface model), mask file, stacking number file, header and quality assurance information. The DSM data comes in two versions that differ in the resampling method applied for the down-sampling (median and moving averages). The vertical accuracy is claimed to be about 4.4 m (standard deviation). Geodetic information: The AW3D30 elevations are vertically referenced to the EGM96 geoid and horizontally referenced to the WGS84 (World Geodetic System 1984). Further notes: The AW3D data set can be considered as a digital surface model (DSM), representing elevations of the bare ground where vegetation cover or buildings are absent, and otherwise elevations of the surface objects (e.g. vegetation). Users are requested to share their experiences with the AW3D in geodetic applications with IDEMS. Data access: The Homepage of AW3D30 dataset can be reached on http://www.eorc.jaxa.jp/ALOS/en/aw3d30/ , with data searching function available on dedicated search page of JAXA, available on http://www.eorc.jaxa.jp/ALOS/en/aw3d30/data/index.htm . Users need to register before downloading the dataset, on http://www.eorc.jaxa.jp/ALOS/en/aw3d30/registration.htm . References: JAXA, ALOS Global DSM AW3D30 Dataset Product Format Description for V 1.1, available on http://www.eorc.jaxa.jp/ALOS/en/aw3d30/aw3d30v11_format_e.pdf Tadono, T, H. Ishida, F. Oda, S. Naito, K. Minakawa and H. Iwamoto. Precise Global DEM Generation by ALOS-PRISM. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol.II-4, pp.71-76, 2014. Available on http://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/II-4/71/2014/isprsannals-II-4-71-2014.pdf J. Takaku, T. Tadono, K. Tsutsui, M. Ichikawa. Validation of ‘AW3D’ Global DSM Generated from ALOS PRISM, ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol.III-4, pp.25-31, 2016. Available on http://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/III-4/25/2016/isprs-annals-III-4-25-2016.pdf © Japan Aerospace Exploration Agency (JAXA)