White Paper
PlanetDEM 30 Plus
PlanetObserver
10/12/2015
PlanetObserver France – www.planetobserver.com – msat@planetobserver.com – Tel. +33 4 73 44 19 00
White Paper – PlanetDEM 30 Plus – PlanetObserver
1. Introduction
PlanetObserver presents PlanetDEM 30 Plus, a new Digital Elevation Model (DEM) offering global
coverage and reliable data at 30-meter resolution.
Background information
The NASA Shuttle Radar Topographic Mission (SRTM) has provided digital elevation data for all land
between 56 degrees south and 60 degrees north latitude, which comprises 80% of Earth’s total
landmass.
The NASA has initially released the SRTM dataset at 3 Arc-Seconds (approx. 90 meters) for nearglobal coverage. The latest SRTM data version released by the NASA offers 1 Arc-Second resolution
(approx. 30 meters) for the entire dataset.
The SRTM dataset at 1 Arc-Second is a void-filled elevation dataset processed by the NASA. Although
the product has been corrected, some tiles still contain voids and pervasive artifacts, pits and bumps.
The SRTM data coverage is limited up to 60 degrees north and 56 degrees south. There is a lack of
coverage for all polar regions, including Norway and Sweden.
PlanetObserver has developed PlanetDEM 30 Plus, a new high quality elevation dataset offering 30meter resolution globally. PlanetDEM 30 Plus is processed from SRTM 1 Arc-Second data thoroughly
corrected and combined with other source data. All input elevation data have been compiled and
extensively reprocessed in order to offer a comprehensive global DEM with precise, corrected and
detailed information for the entire Earth.
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White Paper – PlanetDEM 30 Plus – PlanetObserver
2. Product features
2.1 Global coverage
PlanetDEM 30 Plus elevation product covers all emerged lands (at 99%).
The above map shows SRTM data coverage in grey. It is limited to all land between 60 degrees north
and 56 degrees south latitude. All void areas and artifacts still present in the SRTM 30m elevation
dataset have been identified and corrected by using ASTER 30m elevation data. Corrected areas are
identified in orange on the map. Extensive data corrections have been carried out on all mountainous
regions across the world and in many desert areas in Africa and the Middle East.
On the map, blue areas correspond to the additional elevation data that have been compiled beyond
60° north latitude and 56° south latitude, areas uncovered by SRTM data. Those elevation data come
all from highly reliable sources.
2.2 Data sources
PlanetDEM 30 Plus is processed from different source data:


SRTM 1 Arc-Second (from 60 degrees north to 56 degrees south latitude) corrected with
ASTER data in several places:
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Mountain areas: Andes, Alps, Himalayas, Southeast Asia, New Zealand, etc.
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Desert: Mauritania, Algeria, Libya, Egypt, Arabian Peninsula, etc.
For areas uncovered by SRTM data, accurate sources have been used:
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Antarctica: NSIDC (National Snow and Ice Data Center)
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Alaska: AGDC (Alaska Geospatial Data Clearinghouse)
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Canada: CDED (Canadian Digital Elevation Data) from Geobase
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Greenland, Iceland and Svalbard: topographic maps
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North Atlantic Islands, North Scandinavia, North Russia and North Siberia: Russian maps
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White Paper – PlanetDEM 30 Plus – PlanetObserver
2.3 Corrections
PlanetDEM 30 Plus is a global elevation composite dataset processed with different source data.
Specific processing methods have been developed and applied, with a particular focus on edge
smoothing processing in order to produce a seamless and global DEM product.
Voids and artifacts due to clouds, sand and shadow effect still present in SRTM 1 Arc-Second dataset
have been carefully identified and corrected with ASTER 30m data.
2.4 Data specifications
PlanetDEM 30 Plus specifications in terms of vertical and horizontal accuracy are similar to SRTM
specs which are reported to be as follows:
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Vertical accuracy (LE95): 14 meters
-
Horizontal accuracy (CE95): 10 meters
Oceans are set to 0 meter.
Negative values are present in areas under the sea level.
2.5 Data structure and format

Resolution :
PlanetDEM 30 Plus is available with a resolution of 1 Arc-Second (approx. 30m resolution).

File format :
The product is available in the following formats:
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GEOTIFF, 16 bit-format, divided in 5° x 5° tiles (18,000 x 18,000 pixels), for a total of 1,449
tiles ; total data size: 876 GB.
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DTED 2, divided in 1° x 1° tiles, for a total of 25,518 tiles; total data size: 397 GB.
Both file formats are supplied without tiles containing water only.

Tile naming :
For GeoTiff format, tiles are named as follows: PlanetDEM_30_Plus_(N or S)(yy)(W or E)(xxx).tif
N or S = tile upper latitude
W or E = tile left longitude

Projection :
The product comes in Geographic (latitude-longitude) projection, WGS84.
Other projections can be provided on demand for specific AOIs.
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White Paper – PlanetDEM 30 Plus – PlanetObserver
3. Comparaison: PlanetDEM 30 Plus vs. SRTM
SRTM
PlanetDEM 30 Plus
Desert, Egypt
SRTM
PlanetDEM 30 Plus
Coastal area, Indonesia
SRTM
PlanetDEM 30 Plus
Himalayas
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White Paper – PlanetDEM 30 Plus – PlanetObserver
SRTM
PlanetDEM 30 Plus
Alps
SRTM
PlanetDEM 30 Plus
Fjords, Chile
SRTM
PlanetDEM 30 Plus
Desert, Niger
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