El LIDAR Composite DTM/DSM es un modelo de terreno ráster que cubre aproximadamente el 99% de Inglaterra con una resolución espacial de 1 m y que la Agencia de Medio Ambiente del Reino Unido produjo en 2022. El modelo contiene 3 bandas de datos de terreno: un modelo digital del terreno (DTM), un modelo digital de superficie (DSM) de primer retorno y un DSM de último retorno. …

The digital ground model numerically defines the morphology of the ground by means of a system of discrete points known through the spatial coordinates x,y and z. The sampling pitch used is 40 meters. The reference system is the Gauss-Boaga merged East.

MERIT (Multi-Error-Removed Improved Terrain DEM) is a substantially improved near-global terrain description with 90 m (3 arc-seconds) spatial resolution (Yamazaki et al. 2017). MERIT covers almost all of Earth’s land areas within 90N-60S, except of Antarctica. Different to most other global DEM data sets, MERIT provides – in good approximation – elevations of the bare ground. This has been achieved by reducing vegetation heights (known as tree height bias) using tree density and tree height maps as auxiliary information in the production of the MERIT DEM. However, over built areas, MERIT elevations may contain a bias due to urban canopy.MERIT relies on SRTM v2.1 South of 60° latitude, ALOS AW3D North of 60° latitude, and uses elevations from Viewfinder Panoramas (VFP-DEM) to fill voids (unobserved areas) where present. For the void-filling with VFP-DEM, an average matching method has been applied by Yamazaki et al. (2017) to ensure smooth transitions. Within the SRTM data area, about 0.5 % of MERIT land cells rely on VFP-DEM. North of 60°, the contribution of VFP-DEM is about ~30 %. As a result, elevation errors previously present in the SRTM model have been reduced such that actual terrain features stand out more clearly.

Geodetic information: The MERIT DEMs are vertically referenced to the EGM96 geoid and horizontally referenced to the WGS84 (World Geodetic System 1984).

Further notes: The MERIT DEM mostly represents bare ground elevations, so is technically close to a digital terrain model (DTM). This makes the data set suitable for applications requiring heights of the bare ground. Example areas are hydrology, hydrodynamics, physical geodesy and geophysics.

Data access: The authors freely share their model for non-commercial applications (e.g. science and education) via URL: hydro.iis.u-tokyo.ac.jp/~yamadai/MERIT_DEM/

References:

Yamazaki, D., D. Ikeshima, R. Tawatari, T. Yamaguchi, F. O’Loughlin, J.C. Neal, C.C. Sampson, S. Kanae, P.D. Bates (2017), A high accuracy map of global terrain elevations, Geophysical Research Letters, Doi: 10.1002/2017GL072874

This is a tiled collection of the 3D Elevation Program (3DEP) and is one meter resolution. The 3DEP data holdings serve as the elevation layer of The National Map, and provide foundational elevation information for earth science studies and mapping applications in the United States. Scientists and resource managers use 3DEP data for hydrologic modeling, resource monitoring, mapping and visualization, and many other applications. The elevations in this DEM represent the topographic bare-earth surface. USGS standard one-meter DEMs are produced exclusively from high resolution light detection and ranging (lidar) source data of one-meter or higher resolution. One-meter DEM surfaces are seamless within collection projects, but, not necessarily seamless across projects. The spatial reference used for tiles of the one-meter DEM within the conterminous United States (CONUS) is Universal Transverse Mercator (UTM) in units of meters, and in conformance with the North American Datum of 1983 ...

Modelos digitales de la superficie (DSM) y el terreno (DTM) derivados de los datos LiDAR de NEON. DSM: Funciones de superficie (información topográfica con vegetación y estructuras artificiales). DTM: Elevación del terreno sin vegetación (información topográfica sin vegetación ni estructuras artificiales). Las imágenes se proporcionan en metros sobre el nivel medio del mar y se combinan en un mosaico sobre un…

Layers include: Ensemble Digital Terrain Model (EDTM) in 250-m resolution. Unit is in metre(m) and precision is in decimetre (dm). Maps are downscaled from 30-m resolution to 250-m in order to fit the size limit. We provide 30-m EDTM and its standard deviation as links:

• 30-m EDTM

https://s3.eu-central-1.wasabisys.com/openlandmap/dtm/dtm.bareearth_ensemble_p10_30m_s_2018_go_epsg4326_v20230221.tif

• Standard deviation

https://s3.eu-central-1.wasabisys.com/openlandmap/dtm/dtm.bareearth_ensemble_std_30m_s_2018_go_epsg4326_v20230221.tif

Derived using ALOS AW3D, GLO-30, MERITDEM, and national DTMs. We derived a lower 10% quantile from all maps. In order to create bare earth data, we used canopy height (canopy height > 2m) and standard deviation (sd > 6m) to mask building and forest in AW3D and GLO-30. Practical processing is written here in Python.

To access and visualize maps use: OpenLandMap.org

If you discover a bug, artifact or inconsistency, or if you have a question please use some of the following channels:

• Technical issues and questions about the code: https://gitlab.com/openlandmap/global-layers/-/issues
• General questions and comments: https://disqus.com/home/forums/landgis/

All files internally compressed using "COMPRESS=DEFLATE" creation option in GDAL in Cloud Optimised GeoTiff (COG). File naming convention:

• dtm.bareearth = variable: digital terrain model (m), bare earth
• ensemble = determination method: ensemble of mutli-source dsm and dtm
• p10/std = aggregation/statistics method: 10th percentile / standard deviation
• 250m = spatial resolution / block support: 250 m,
• s = vertical reference: at surface,
• go = bounding box: global land without Antarctica
• epsg.4326 = ESPG code: epsg.4326
• v20230221 = version code: creation date 20230221

Elevation data is a point, line or surface geographically located in the x and y relative to a horizontal datum, that includes a height (z) above or below a known vertical datum. Bathymetry will deal with all offshore elevation data. - Elevation data will include both raw elevation data and digital elevation models (DEM); - Spot Heights, points on the earth's surface, of known elevation. - Contours, lines which represents an imaginary line on the ground joining points of equal elevation. - Horizontal Control Points, points on the ground, the horizontal position of which has been determined by geodetic survey. - Digital Elevation Models (DEM) are interpolated representations of a surface. Elevation points are spaced at a regular interval so as to create a grid or lattice. These grids can be directly observed or, more generally, they are computed from more than one of the above mentioned irregular spaced elevations. - Digital Terrain Models (DTM) are bare earth DEM's representing the terrain They are interpolated using a combination of elevation information and could also be constrained using break lines, such are cliffs, drainage, coast etc. - Digital Surface Models (DSM) are also DEM's, but they include non-surface objects like trees, buildings etc. So, a DSM = DTM + all non surface objects. - Triangulated Irregular Network (TIN). A vector data structure that partitions geographic space into contiguous, nonoverlapping triangles. The vertices of each triangle are sample data points with x, y, and z values. These sample points are connected by lines to form Delaunay triangles. TINs are used to store and display elevation models. - Hydrologically enforced Digital Elevation Models (HDEM) represents DEM with drainage enforcement. The quality of a DEM is a measure of how accurate elevation is at each pixel (absolute accuracy) and how accurately the morphology is represented (relative accuracy). Several factors affect the quality of DEM-derived products: terrain roughness, sampling density (elevation data collection method), grid resolution or pixel size, interpolation algorithm, vertical resolution and terrain analysis algorithm.

Das digitale Bodenmodell definiert numerisch die Morphologie des Bodens mittels eines Systems diskreter Punkte, die durch die räumlichen Koordinaten x,y und z bekannt sind. Das Referenzsystem ist die Gauß-Boaga fusioniert Osten.

The Digital Terrain Model of the Czech Republic of the 4th generation (DMR 4G) represents a picture of natural or by human activity modified terrain surface in digital form as heights of discrete points in a regular grid (5 x 5 m) with coordinates X,Y,H, where H means the altitude in the Baltic Vertical Datum - After Adjustment with total standard error of 0.3 m of height in the bare terrain and 1 m in forested terrain. The model is based on the data acquired by altimetry airborne laser scanning of the Czech Republic territory between years 2009 and 2013. DMR4G is established to analyse terrain situation at regional scale and character, e.g. for extensive transport and water management projects planning, natural phenomena modelling etc.