ASTER GDEM v1

Japan’s Ministry of Economy, Trade and industry (METI) and NASA released a GDEM on 29 June 2009. This GDEM (Global Digital Elevation Model) was created by stereo-correlating the 1.3 million scene ASTER VNIR archive, covering the Earth’s land surface between 83N and 83S latitudes from the year 2000 onwards. ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is an imaging instrument flying on Terra, a satellite launched in December 1999 as part of NASA's Earth Observing System (EOS).

The GDEM covers land surfaces between 83°N and 83°S with estimated accuracies of 20 meters at 95% confidence for vertical data and 30 meters at 95% confidence for horizontal data. By contrast the horizontal resolution for the SRTM data is 90m.

The raw data is available for free from http://asterweb.jpl.nasa.gov/gdem.asp

Malaysia

A rectangular block from (N0 to N8, E99 to E121) including the whole of Malaysia, Singapore and Brunei but also including portions of Indonesia, Thailand and the Philippines has just been compiled. The total size is 472Mb.

Tiles are named as 60NN1EEE.img where NN is the number of degrees North and EEE is the number of degrees East of the lower left corner of the tile (all tiles are 1 degree squared). The "60" represents Malaysia's IDD code, "1" represents v1.

Problems

Although the ASTER-GDEM v1 is generally smoother and more detailed compared to SRTM v4, there are a few problems that I've noticed so far:

1. There are 'holes' - areas of persistent cloud cover - which are quite messed up indeed.

2. Don't know quite how to describe this but certain parts have lots of unnatural straight lines ...

Technical details

Vectorisation done with dem2topo:
SF 5
Minor 10m
Intermediate 100m
Major 500m
Shoreline 2m

The Polish Map (.mp) file header (this is the settings I used for compilation with cgpsmapper). I noticed that there is quite considerable degradation in the quality of the data after conversion with cgpsmapper despite using the highest setting for SimplifyLevel.
ID=60001099
Name=maps.three15.org ASTER-GDEM1
Elevation=M
Preprocess=N
TreSize=1000
RgnLimit=1024
POIIndex=N
Copyright=Data sources http://asterweb.jpl.nasa.gov/|Compilation http://maps.three15.org/
Levels=4
Level0=22
Level1=20
Level2=18
Level3=15
Zoom0=0
Zoom1=1
Zoom2=2
Zoom3=3
DrawPriority=26
Transparent=Y
SimplifyLevel=10

Have a look at the quality of the ASTER-GDEMv1 compared with SRTMv4 ...