Digital elevation model: Difference between revisions

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{{quotation|A '''digital elevation model''' (DEM) is a digital representation of ground surface topography or terrain. It is also widely known as a '''digital terrain model(DTM)'''. A DEM can be represented as a raster (a grid of squares) or as a triangular irregular network.}} ([http://en.wikipedia.org/wiki/Digital_terrain_model Wikipedia], retrieved 16:06, 12 May 2010 (UTC)).
{{quotation|A '''digital elevation model''' (DEM) is a digital representation of ground surface topography or terrain. It is also widely known as a '''digital terrain model(DTM)'''. A DEM can be represented as a raster (a grid of squares) or as a triangular irregular network.}} ([http://en.wikipedia.org/wiki/Digital_terrain_model Wikipedia], retrieved 16:26, 12 May 2010 (UTC)).
   
   
A '''digital surface model''' (DSM) on the other hand includes buildings, vegetation, and roads, as well as natural terrain features. The DEM provides a so-called bare-earth model, devoid of landscape features. While a DSM may be useful for landscape modeling, city modeling and visualization applications, a DEM is often required for flood or drainage modeling, land-use studies, geological applications, and much more. ([http://en.wikipedia.org/wiki/Digital_terrain_model Wikipedia], retrieved 16:06, 12 May 2010 (UTC)).
A '''digital surface model''' (DSM) on the other hand includes buildings, vegetation, and roads, as well as natural terrain features. The DEM provides a so-called bare-earth model, devoid of landscape features. While a DSM may be useful for landscape modeling, city modeling and visualization applications, a DEM is often required for flood or drainage modeling, land-use studies, geological applications, and much more. ([http://en.wikipedia.org/wiki/Digital_terrain_model Wikipedia], retrieved 16:26, 12 May 2010 (UTC)).


== File Formats ==
== File Formats ==
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* Vector data either can be points (locations), lines or polylines (e.g. for topographics lines or roads), or polygons.  
* Vector data either can be points (locations), lines or polylines (e.g. for topographics lines or roads), or polygons.  


{{quotation|Additional non-spatial data can also be stored along with the spatial data represented by the coordinates of a vector geometry or the position of a raster cell. In vector data, the additional data contains attributes of the feature. For example, a forest inventory polygon may also have an identifier value and information about tree species. In raster data the cell value can store attribute information, but it can also be used as an identifier that can relate to records in another table.}} ([http://en.wikipedia.org/wiki/Geographic_information_system Wikipedia], retrieved 16:06, 12 May 2010 (UTC)).
{{quotation|Additional non-spatial data can also be stored along with the spatial data represented by the coordinates of a vector geometry or the position of a raster cell. In vector data, the additional data contains attributes of the feature. For example, a forest inventory polygon may also have an identifier value and information about tree species. In raster data the cell value can store attribute information, but it can also be used as an identifier that can relate to records in another table.}} ([http://en.wikipedia.org/wiki/Geographic_information_system Wikipedia], retrieved 16:26, 12 May 2010 (UTC)).


; Digital elevation models
; Digital elevation models


{{quotation| The [http://en.wikipedia.org/wiki/USGS_DEM USGS DEM] standard is a geospatial file format developed by the United States Geological Survey for storing a raster-based digital elevation model. It is an open standard, and is used throughout the world. It has been superseded by the USGS's own SDTS format but the format remains popular due to large numbers of legacy files, self-containment, relatively simple field structure and broad, mature software support.}} (Wikipedia, retrieved 16:06, 12 May 2010 (UTC))
;USGS DEM:
: {{quotation| The [http://en.wikipedia.org/wiki/USGS_DEM USGS DEM] standard is a geospatial file format developed by the United States Geological Survey for storing a raster-based digital elevation model. It is an open standard, and is used throughout the world. It has been superseded by the USGS's own SDTS format but the format remains popular due to large numbers of legacy files, self-containment, relatively simple field structure and broad, mature software support.}} (Wikipedia, retrieved 16:26, 12 May 2010 (UTC))


{{quotation| The [http://mcmcweb.er.usgs.gov/sdts/ The Spatial Data Transfer Standard] (SDTS) is a robust way of transferring earth-referenced spatial data between dissimilar computer systems with the potential for no information loss. It is a transfer standard that embraces the philosophy of self-contained transfers, i.e. spatial data, attribute, georeferencing, data quality report, data dictionary, and other supporting metadata all included in the transfer.}} ([http://mcmcweb.er.usgs.gov/sdts/ USGS], retrieved 16:06, 12 May 2010 (UTC))
; SDTS
{{quotation| The [http://mcmcweb.er.usgs.gov/sdts/ The Spatial Data Transfer Standard] (SDTS) is a robust way of transferring earth-referenced spatial data between dissimilar computer systems with the potential for no information loss. It is a transfer standard that embraces the philosophy of self-contained transfers, i.e. spatial data, attribute, georeferencing, data quality report, data dictionary, and other supporting metadata all included in the transfer.}} ([http://mcmcweb.er.usgs.gov/sdts/ USGS], retrieved 16:26, 12 May 2010 (UTC))


{{quotation|DTED (or Digital Terrain Elevation Data) is a standard of digital datasets which consists of a matrix of terrain elevation values. This standard was originally developed in the 1970s to support aircraft radar simulation and prediction.}} ([http://en.wikipedia.org/wiki/DTED DTED] (Wikipedia, retrieved 16:06, 12 May 2010 (UTC))
; DTED
{{quotation|DTED (or Digital Terrain Elevation Data) is a standard of digital datasets which consists of a matrix of terrain elevation values. This standard was originally developed in the 1970s to support aircraft radar simulation and prediction.}} ([http://en.wikipedia.org/wiki/DTED DTED] (Wikipedia, retrieved 16:26, 12 May 2010 (UTC))


; General puporse 3D formats
; Surface models
 
; SRTM
: {{quotation|The Shuttle Radar Topography Mission (SRTM) is a partnership between NASA and the National Geospatial-Intelligence Agency (NGA). Flown aboard the NASA Space Shuttle Endeavour (11-22 February 2000), SRTM fulfilled its mission to map the world in three dimensions.}} ([http://eros.usgs.gov/ EORS.usgs.gov])
 
 
; General pupose 3D formats


* See [[3D file format]]s
* See [[3D file format]]s
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== Available terrain maps ==
== Available terrain maps ==


; STRM
[http://www2.jpl.nasa.gov/srtm/ The Shuttle Radar Topography Mission (SRTM)] Maps.
Download links:
* [http://dds.cr.usgs.gov/srtm/ directory]. Read [http://dds.cr.usgs.gov/srtm/What_are_these.pdf What_are_these.pdf] first. Can be imported to ARCInfo with a little work (not tested)


; GTOPS30
; GTOPS30
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[http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/gtopo30_info GTOPO30] is a global digital elevation model (DEM) of the whole world with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GTOPO30 was derived from several raster and vector sources of topographic information.
[http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/gtopo30_info GTOPO30] is a global digital elevation model (DEM) of the whole world with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GTOPO30 was derived from several raster and vector sources of topographic information.


; Download links
Download links:
* [http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/gtopo30_info GTOPO30] (US Geological survey EROS Data Center)
* [http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/gtopo30_info GTOPO30] (US Geological survey EROS Data Center)
* [ftp://edcftp.cr.usgs.gov/pub/data/gtopo30/global/ GTOPO30 FTP Server]
* [ftp://edcftp.cr.usgs.gov/pub/data/gtopo30/global/ GTOPO30 FTP Server]

Revision as of 18:26, 12 May 2010

Draft

“A digital elevation model (DEM) is a digital representation of ground surface topography or terrain. It is also widely known as a digital terrain model(DTM). A DEM can be represented as a raster (a grid of squares) or as a triangular irregular network.” (Wikipedia, retrieved 16:26, 12 May 2010 (UTC)).

A digital surface model (DSM) on the other hand includes buildings, vegetation, and roads, as well as natural terrain features. The DEM provides a so-called bare-earth model, devoid of landscape features. While a DSM may be useful for landscape modeling, city modeling and visualization applications, a DEM is often required for flood or drainage modeling, land-use studies, geological applications, and much more. (Wikipedia, retrieved 16:26, 12 May 2010 (UTC)).

File Formats

Both digital elevation and surface models can either be represented as raster or vector graphics.

  • Raster data can present either just images (as in any image format like *.jpg*) or include specific data about a cell.
  • Vector data either can be points (locations), lines or polylines (e.g. for topographics lines or roads), or polygons.

“Additional non-spatial data can also be stored along with the spatial data represented by the coordinates of a vector geometry or the position of a raster cell. In vector data, the additional data contains attributes of the feature. For example, a forest inventory polygon may also have an identifier value and information about tree species. In raster data the cell value can store attribute information, but it can also be used as an identifier that can relate to records in another table.” (Wikipedia, retrieved 16:26, 12 May 2010 (UTC)).

Digital elevation models
USGS DEM
“The USGS DEM standard is a geospatial file format developed by the United States Geological Survey for storing a raster-based digital elevation model. It is an open standard, and is used throughout the world. It has been superseded by the USGS's own SDTS format but the format remains popular due to large numbers of legacy files, self-containment, relatively simple field structure and broad, mature software support.” (Wikipedia, retrieved 16:26, 12 May 2010 (UTC))
SDTS

“The The Spatial Data Transfer Standard (SDTS) is a robust way of transferring earth-referenced spatial data between dissimilar computer systems with the potential for no information loss. It is a transfer standard that embraces the philosophy of self-contained transfers, i.e. spatial data, attribute, georeferencing, data quality report, data dictionary, and other supporting metadata all included in the transfer.” (USGS, retrieved 16:26, 12 May 2010 (UTC))

DTED

“DTED (or Digital Terrain Elevation Data) is a standard of digital datasets which consists of a matrix of terrain elevation values. This standard was originally developed in the 1970s to support aircraft radar simulation and prediction.” (DTED (Wikipedia, retrieved 16:26, 12 May 2010 (UTC))

Surface models
SRTM
“The Shuttle Radar Topography Mission (SRTM) is a partnership between NASA and the National Geospatial-Intelligence Agency (NGA). Flown aboard the NASA Space Shuttle Endeavour (11-22 February 2000), SRTM fulfilled its mission to map the world in three dimensions.” (EORS.usgs.gov)


General pupose 3D formats

Available terrain maps

STRM

The Shuttle Radar Topography Mission (SRTM) Maps.

Download links:

GTOPS30

GTOPO30 is a global digital elevation model (DEM) of the whole world with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GTOPO30 was derived from several raster and vector sources of topographic information.

Download links:

Other

Advanced Spaceborne Thermal Emission and Reflection Radiometer

Links

Overviews

Visualization and GIS

(these are related subjects)

Overviews and indexes of File formats

Actors

Online maps to look at

(some can show relief).

  • Web Map Services
  • Maps-For-Free.com. Allows to display various Layers on either satellite, terrain, relief or OSM view. Allows to take a picture (jpg).
  • GloVis (USGS Global Visualization) is an online search and order tool for selected satellite data.
  • WIST (Warehouse Inventory Search Tool) is a web-based client to search and order earth science data from various NASA and affiliated center.
  • MRTWeb combines familiar capabilities of the USGS Global Visualization Viewer (GloVis) and the downloadable MODIS Reprojection Tool (MRT)

To sort out

Printing with a RepRap printer

(e.g. a RapMan)

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