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 ...

The Smoothed Digital Elevation Model (DEM-S) was derived from the SRTM data acquired by NASA in February 2000. DEM-S represents ground surface topography (excluding vegetation features) and has been smoothed to reduce noise and improve the representation of surface shape. An adaptive process applied more smoothing in flatter areas than hilly areas, and more smoothing in noisier areas than in less noisy areas. This DEM-S supports calculation of local terrain shape attributes such as slope, aspect, and curvature that could not be reliably derived from the unsmoothed 1 second DEM because of noise. There are several areas with unexpected negative values: close to Canberra around (150.443044, -35.355281) with values of -55 and in Western Australia around (124.84, -16.44) with -43.

This is a tiled collection of the 3D Elevation Program (3DEP) and is 1 arc-second (approximately 30 m) resolution. The elevations in this Digital Elevation Model (DEM) represent the topographic bare-earth surface. 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 seamless 1 arc-second DEM layers are derived from diverse source data that are processed to a common coordinate system and unit of vertical measure. These data are distributed in geographic coordinates in units of decimal degrees, and in conformance with the North American Datum of 1983 (NAD 83). All elevation values are in meters and, over the continental United States, are referenced to the North American Vertical Datum of 1988 (NAVD88). The seamless 1 arc-second DEM layer provides coverage of the conterminous United States, Hawaii, Puerto Rico, other territorial islands, and much of Alaska and Canada. The seamless 1 arc-second DEM is available as pre-staged current and historical products tiled in GeoTIFF format. The seamless 1 arc-second DEM layer is updated continually as new data become available in the current folder. Previously created 1 degree blocks are retained in the historical folder with an appended date suffix (YYYYMMDD) when they were produced. Other 3DEP products are nationally seamless DEMs in resolutions of 1 and 1/3 arc-second. These seamless DEMs were referred to as the National Elevation Dataset (NED) from about 2000 through 2015 at which time they became the seamless DEM layers under the 3DEP program and the NED name and system were retired. Other 3DEP products include one-meter DEMs produced exclusively from high resolution light detection and ranging (lidar) source data and five-meter DEMs in Alaska as well as various source datasets including the lidar point cloud and interferometric synthetic aperture radar (Ifsar) digital surface models and intensity images. All 3DEP products are public domain.

This is a tiled collection of the 3D Elevation Program (3DEP) and is 2 arc-second (approximately 60 m) resolution covering Alaska. The elevations in this Digital Elevation Model (DEM) represent the topographic bare-earth surface. 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 seamless 2 arc-second DEM layers are derived from diverse source data that are processed to a common coordinate system and unit of vertical measure. These data are distributed in geographic coordinates in units of decimal degrees, and in conformance with the North American Datum of 1983 (NAD 83). All elevation values are in meters and, over the continental United States, are referenced to the North American Vertical Datum of 1988 (NAVD88). The seamless 2 arc-second DEM layer provides coverage of the Alaska only. The seamless 2 arc-second DEM is available as pre-staged current and historical products tiled in GeoTIFF format. The seamless 2 arc-second DEM layer is updated continually as new data become available in the current folder. Previously created 1 degree blocks are retained in the historical folder with an appended date suffix (YYYYMMDD) when they were produced. Other 3DEP products are nationally seamless DEMs in resolutions of ⅓ and 1 -arc-second. These seamless DEMs were referred to as the National Elevation Dataset (NED) from about 2000 through 2015 at which time they became the seamless DEM layers under the 3DEP program and the NED name and system were retired. Other 3DEP products include one-meter DEMs produced exclusively from high resolution light detection and ranging (lidar) source data and five-meter DEMs in Alaska as well as various source datasets including the lidar point cloud and interferometric synthetic aperture radar (Ifsar) digital surface models and intensity images. All 3DEP products are public domain.

Abstract

The dataset was derived by the Bioregional Assessment Programme from the 1 second SRTM Digital Elevation Model (DEM) dataset. The source dataset is identified in the Lineage field in this metadata statement. The processes undertaken to produce this derived dataset are described in the History field in this metadata statement.

A clipped version of the Australia wide 1 second -S DEM, version 1, which limits the size to the rectangular extent of the Galilee Basin Subregion, enhancing speed and efficiency for visualisation and processing.

The metadata for the Geoscience Australia 1 sec SRTM is below:

The 1 second DSM, DEM, DEM-S and DEM-H are national elevation data products derived from the Shuttle Radar Topography Mission (SRTM) data. The SRTM data is not suitable for routine application due to various artefacts and noise.

The data has been treated with several processes to produce more usable products:

\* A cleaned digital surface model (DSM)

\* regular grid representing ground surface topography as well as other features including vegetation and man-made structures

\* A bare-earth digital elevation model (DEM)

\* regular grid representing ground surface topography, and where possible, excluding other features such as vegetation and man-made structures.

\* A smoothed digital elevation model (DEM-S)

\* A smoothed DEM based on the bare-earth DEM that has been adaptively smoothed to reduce random noise typically associated with the SRTM data in low relief areas.

\* A hydrologically enforced digital elevation model (DEM-H)

\* A hydrologically enforced DEM is based on DEM-S that has had drainage lines imposed and been further smoothed using the ANUDEM interpolation software.

The last product, a hydrologically enforced DEM, is most similar to the DEMs commonly in use around Australia, such as the GEODATA 9 Second DEM and the 25 m resolution DEMs produced by State and Territory agencies from digitised topographic maps.

For any analysis where surface shape is important, one of the smoothed DEMs (DEM-S or DEM-H) should be used. DEM-S is preferred for shape and vertical accuracy and DEM-H for hydrological connectivity. The DSM is suitable if you want to see the vegetation as well as the land surface height. There are few cases where DEM is the best data source, unless access to a less processed product is necessary.

The 1 second DEM (in its various incarnations) has quite different characteristics to DEMs derived by interpolation from topographic data. Those DEMs are typically quite smooth and are based on fairly accurate but sparse source data, usually contours and spot heights supplemented by drainage lines. The SRTM data is derived from radar measurements that are dense (there is essentially a measurement at almost every grid cell) but noisy.

Version 1.0 of the DSM was released in early 2009 and version 1.0 of the DEM was released in late 2009. Version 1.0 of the DEM-S was released in July 2010 and version 1.0 of the hydrologically enforced DEM-H was released in October 2011. These products provide substantial improvements in the quality and consistency of the data relative to the original SRTM data, but are not free from artefacts. Improved products will be released over time.

The 3 second products were derived from the 1 second data and version 1.0 was released in August 2010. Future releases of these products will occur when the 1 second products have been improved. At this stage there is no 3 second DEM-H product, which requires re-interpolation with drainage enforcement at that resolution.

Purpose

To enhance the speed and efficiency for visualisation and processing of the smoothed 1 second DEM data within the Galilee Basin Subregion

Dataset History

The original, Australia wide, 1 second smoothed DEM was clipped to rectangular extents of the Galilee subregion using the Spatial Analyst 'Extract By Rectangle' tool in ESRI ArcCatalog v10.0 with the following parameters:

Input raster: source 1 second SRTM

Extent: Galilee Basin subregion polygon

Extraction Area: INSIDE

'no data' values are created outside the clip extent therefore the extent of the dataset may still reflect the national DEM extent in ArcCatalog. Check the tool details for more info.

The lineage of the source 1 second SRTM is below:

The following datasets were used to derive this version of the 1 second DEM products:

Source data

1. SRTM 1 second Version 2 data (Slater et al., 2006), supplied by Defence Imagery and Geospatial Organisation (DIGO) as 813 1 x 1 degree tiles. Data were produced by NASA from radar data collected by the Shuttle Radar Topography Mission in February 2000.

2. GEODATA 9 second DEM Version 3 (Geoscience Australia, 2008) used to fill voids.

3. SRTM Water Body Data (SWBD) shapefile accompanying the SRTM data (Slater et al., 2006). This defines the coastline and larger inland waterbodies for the DEM and DSM.

4. Vegetation masks and water masks applied to the DEM to remove vegetation.

Full metadata, methodologies and lineage descriptions can be found in the PDF userguide within this dataset.

Dataset Citation

Bioregional Assessment Programme (2014) Smoothed Digital Elevation Model (DEM) - 1 arc second resolution - Clipped to Galilee Subregion extent. Bioregional Assessment Derived Dataset. Viewed 10 December 2018, http://data.bioregionalassessments.gov.au/dataset/0fe257aa-8845-4183-9d05-5b48edd98f34.

Dataset Ancestors

• Derived From Geoscience Australia, 1 second SRTM Digital Elevation Model (DEM)

To advance the U.S. Geological Survey 3D National Topography Model (3DNTM) including the next generation of the 3D Elevation Program (3DEP) and the 3D Hydrography Program (3DHP), the USGS researched and created a Seamless 1-meter resolution (S1M) Digital Elevation Model (DEM) for the conterminous United States (CONUS). This dataset is a result of a joint project between the National Geospatial Technical Operations Center (NGTOC) and the Earth Resources Observation and Science Center (EROS) of the USGS National Geospatial Directorate (NGD). Scientists and resource managers can use the S1M data for global change research, hydrologic modeling, resource monitoring, mapping, visualization, and many other applications. A S1M DEM requires merging multiple lidar projects in which the lidar sensor, bare-earth DEM generation methodology, source resolution, datums/projection, unit of measure, and geoid (mean sea level mo ...

This is an image service providing access to bathymetric/topographic digital elevation models stewarded at NOAA's National Centers for Environmental Information (NCEI).There are 5 related image services providing access to Digital Elevation Models:DEM Mosaic (Individual DEMs)DEM Global Mosaic (Elevation Values)DEM Global Mosaic (Color Shaded Relief)CUDEM Mosaic (Elevation Values)CUDEM Mosaic (Color Shaded Relief)NCEI builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to understand and predict changes in Earth's environment, and conserve and manage coastal and marine resources to meet our Nation's economic, social, and environmental needs. They can be used for modeling of coastal processes (tsunami inundation, storm surge, sea-level rise, contaminant dispersal, etc.), ecosystems management and habitat research, coastal and marine spatial planning, and hazard mitigation and community preparedness. For more information about coastal DEMs at NCEI, please see: https://www.ncei.noaa.gov/products/coastal-elevation-models or learn more from our DEM Fact Sheet (1 MB PDF).This service provides data from many individual DEMs combined together as a mosaic (maximum of 80 rasters at once). By default, the rasters are drawn in order of cell size, with higher-resolution grids displayed on top of lower-resolution grids. If overlapping DEMs have the same resolution, the newer one is shown. Alternatively, a single DEM or group of DEMs can be isolated using a filter/definition query or using the "Lock Raster" mosaic method in ArcMap.The DEMs can be viewed in NCEI's Bathymetric Data Viewer along with other bathymetric datasets stewarded at NCEI.Please see NCEI's corresponding DEM Footprints map service for polygon footprints and more information about the individual DEMs used to create this composite view. The newer 1/3 and 1/9 arcsecond "tiled" DEMs are hosted by NOAA's Office for Coastal Management; please see the Data Access Viewer for access to these data. View these services together in a single combined map.This service has a server-side function available. This can be selected in the ArcGIS Online layer using "Image Display", or in ArcMap under "Processing Templates".None: The default. Provides elevation/depth values in meters. Please refer to the vertical datum for each DEM.ColorHillshade: An elevation-tinted hillshade visualization. The depths are displayed using this color ramp:THREDDS catalog (for extracting/downloading DEMs)

This data set contains 8-meter Digital Elevation Model (DEM) mosaics of high mountain Asia glacier and snow regions generated from from very-high-resolution commercial stereo satellite imagery.

This is a tiled collection of the 3D Elevation Program (3DEP) covering Alaska only, and is 5-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 5-meter DEMs are produced exclusively from interferometric synthetic aperture radar (Ifsar) source data of 5-meter or higher resolution. Five-meter DEM surfaces are seamless within collection projects, but, not necessarily seamless across projects. This DEM is delivered in the original resolution, with the original spatial reference. All elevation units have been converted to meters. These data may be used as the source of updates to the seamless 1/3 ...

SUPERSEDED --> See version 4.3

https://data.cnra.ca.gov/dataset/san-francisco-bay-and-sacramento-san-joaquin-delta-dem-for-modeling-version-4-3

Citation and Main Description:

This product is described in Chapter 5 of the 2018 DWR Delta Modeling Section annual report, produced jointly with USGS.

https://data.cnra.ca.gov/dataset/methodology-for-flow-and-salinity-estimates-in-the-sacramento-san-joaquin-delta-and-suisun-marsh/resource/84d4fd29-c839-4efa-82be-b58f7ed176db

Domain and Product

This product is a mutually compatible suite of DEMs covering most of the aquatic and terrestrial areas of the Bay-Delta. The product was derived from original point data collections, lidar and other DEMs. Also included in the resources are images and shapefiles describing the source data.

Changes between 4.1 and 4.2 are documented in the change log below. Changes prior to that are recorded in the 4.1 web page.

Changes in version 4 relative to prior products are limited to the region east of the Carquinez Strait (starting around Carquinez Bridge). To facilitate compatibility between products released by DWR and USGS/NOAA partners, DWR distributes the region west of the active work at 10m resolution but does not actively work in this region. The San Pablo Bay boundary of active revision in the present product in a place where its source data matches that of other Bay elevation models, e.g., the 2m seamless high-resolution bathymetric and topographic DEM of San Francisco Bay by USGS Earth Resources Observation and Science Center (EROS) (https://topotools.cr.usgs.gov/coned/sanfrancisco.php ), the 2010 San Francisco Bay DEM by National Oceanic and Atmospheric Administration (https://www.ngdc.noaa.gov/metaview/page?xml=NOAA/NESDIS/NGDC/MGG/DEM/iso/xml/741.xml&view=getDataView&header=none ) or the prior (version 3) 10m digital elevation model (https://data.cnra.ca.gov/dataset/san-francisco-bay-and-sacramento-san-joaquin-delta-dem-v3 ).The 10m DEM for the Bay-Delta is based on the first on the list, i.e. EROS’ 2m DEM for the Bay

Version: 4.2

• Time Completed: December 2020
• Horizontal Datum: NAD83
• Spheroid:GRS1980
• Projection:UTM_Zone_10N (meters)
• Vertical Datum:NAVD88 (meters)

Changes since 4.1

• Incorporate 1m DEMs from Cache Slough Complex (USGS, 2020) into 2m DEMs for Yolo and North Delta.
• Develop 1m DEM for Lindsey Slough Restoration area based on Handley DEM (UCD, 2015) and Lindsey Slough, Cache Sough, Liberty Island DEM (USGS, 2020) and and merge it into 2m Yolo DEM.
• Develop 2m DEM for Tom Paine Slough based on 2018 Bathymetry Survey (DWR, NCRO) and 2017 LiDAR (DWR) and merge it with 2m DEM for South Delta.
• Develop 2m DEM for Suisun Slough based on 2018 Bathymetry Survey (DWR, NCRO) and 2017 LiDAR (DWR) and merge it with 2m DEM for Montezuma Slough.
• Develop 2m DEM for Georgiana Slough based on 2019 Bathymetry Survey (DWR, NCRO) and 2017 LiDAR (DWR) and merge it with 2m DEM for North Delta.
• Develop 2m DEM for Sacramento River between its junctions with American River and Sutter Slough based on 2019 Bathymetry Survey (DWR, NCRO) and 2017 LiDAR (DWR) and merge it with 2m DEM for North Delta.
• Incorporate all the 2m additions and modifications done for Yolo, North Delta, Montezuma Slough and South Delta into the 10m DEM for Delta and Bay-Delta.

Abstract

This dataset and its metadata statement were supplied to the Bioregional Assessment Programme by a third party and are presented here as originally supplied.

The 3 second (\~90m) Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) version 1.0 was derived from resampling the 1 arc second (\~30m) gridded DEM (ANZCW0703013355). The DEM represents ground surface topography, and excludes vegetation features. The dataset was derived from the 1 second Digital Surface Model (DSM; ANZCW0703013336) by automatically removing vegetation offsets identified using several vegetation maps and directly from the DSM. The 1 second product provides substantial improvements in the quality and consistency of the data relative to the original SRTM data, but is not free from artefacts. Man-made structures such as urban areas and power line towers have not been treated. The removal of vegetation effects has produced satisfactory results over most of the continent and areas with defects are identified in the quality assessment layers distributed with the data and described in the User Guide (Geoscience Australia and CSIRO Land & Water, 2010). A full description of the methods is in progress (Read et al., in prep; Gallant et al., in prep). The 3 second DEM was produced for use by government and the public under Creative Commons attribution.

The 3 second DSM and smoothed DEM are also available (DSM; ANZCW0703014216,

DEM-S; ANZCW0703014217).

Dataset History

Source data

1. SRTM 1 second Version 2 data (Slater et al., 2006), supplied by Defence Imagery and Geospatial Organisation (DIGO) as 813 1 x 1 degree tiles. Data was produced by NASA from radar data collected by the Shuttle Radar Topographic Mission in February 2000.

2. GEODATA 9 second DEM Version 3 (Geoscience Australia, 2008) used to fill voids.

3. SRTM Water Body Data (SWBD) shapefile accompanying the SRTM data (Slater et al., 2006). This defines the coastline and larger inland waterbodies for the DEM and DSM.

4. Vegetation masks and water masks applied to the DEM to remove vegetation.

5. 1 second DEM resampled to 3 second DEM.

1 second DSM processing

The 1 second SRTM-derived Digital Surface Model (DSM) was derived from the 1 second Shuttle Radar Topographic Mission data by removing stripes, filling voids and reflattening water bodies. Further details are provided in the DSM metadata (ANZCW0703013336).

1 second DEM processing (vegetation offset removal)

Vegetation offsets were identified using Landsat-based mapping of woody vegetation. The height offsets were estimated around the edges of vegetation patches then interpolated to a continuous surface of vegetation height offset that was subtracted from the DSM to produce a bare-earth DEM. Further details are provided in the 1 second DSM metadata (ANZCW0703013355).

Void filling

Voids (areas without data) occur in the data due to low radar reflectance (typically open water or dry sandy soils) or topographic shadowing in high relief areas. Delta Surface Fill Method (Grohman et al., 2006) was adapted for this task, using GEODATA 9 second DEM as infill data source. The 9 second data was refined to 1 second resolution using ANUDEM 5.2 without drainage enforcement. Delta Surface Fill Method calculates height differences between SRTM and infill data to create a "delta" surface with voids where the SRTM has no values, then interpolates across voids. The void is then replaced by infill DEM adjusted by the interpolated delta surface, resulting in an exact match of heights at the edges of each void. Two changes to the Delta Surface Fill Method were made: interpolation of the delta surface was achieved with natural neighbour interpolation (Sibson, 1981; implemented in ArcGIS 9.3) rather than inverse distance weighted interpolation; and a mean plane inside larger voids was not used.

Water bodies

Water bodies defined from the SRTM Water Body Data as part of the DSM processing were set to the same elevations as in the DSM.

Edit rules for land surrounding water bodies

SRTM edit rules set all land adjacent to water at least 1m above water level to ensure containment of water (Slater et al., 2006). Following vegetation removal, void filling and water flattening, the heights of all grid cells adjacent to water was set to at least 1 cm above the water surface. The smaller offset (1cm rather than 1m) could be used because the cleaned digital surface model is in floating point format rather than integer format of the original SRTM.

Some small islands within water bodies are represented as voids within the SRTM due to edit rules. These voids are filled as part of void filling process, and their elevations set to a minimum of 1 cm above surrounding water surface across the entire void fill.

Overview of quality assessment

The quality of vegetation offset removal was manually assessed on a 1/8 ×1/8 degree grid. Issues with the vegetation removal were identified and recorded in ancillary data layers. The assessment was based on visible artefacts rather than comparison with reference data so relies on the detection of artefacts by edges.

The issues identified were:

\* vegetation offsets are still visible (not fully removed)

\* vegetation offset overestimated

\* linear vegetation offset not fully removed

\* incomplete removal of built infrastructure and other minor issues

DEM Ancillary data layers

The vegetation removal and assessment process produced two ancillary data layers:

\* A shapefile of 1/8 × 1/8 degree tiles indicating which tiles have been affected by vegetation removal and any issue noted with the vegetation offset removal

\* A difference surface showing the vegetation offset that has been removed; this shows the effect of vegetation on heights as observed by the SRTM radar

instrument and is related to vegetation height, density and structure.

The water and void fill masks for the 1 second DSM were also applied to the DEM. Further information is provided in the User Guide (Geoscience Australia and CSIRO Land & Water, 2010).

Resampling to 3 seconds

The 1 second SRTM derived Digital Elevation Model (DEM) was resampled to 3 seconds of arc (90m) in ArcGIS software using aggregation tool. This tool determines a new cell value based on multiplying the cell resolution by a factor of the input (in this case three) and determines the mean value of input cells with the new extent of the cell (i.e. Mean value of the 3x3 input cells). The 3 second SRTM was converted to integer format for the national mosaic to make the file size more manageable. It does not affect the accuracy of the data at this resolution. Further information on the processing is provided in the User Guide (Geoscience Australia and CSIRO Land & Water, 2010).

Further information can be found at http://www.ga.gov.au/metadata-gateway/metadata/record/gcat_aac46307-fce9-449d-e044-00144fdd4fa6/SRTM-derived+3+Second+Digital+Elevation+Models+Version+1.0

Dataset Citation

Geoscience Australia (2010) Geoscience Australia, 3 second SRTM Digital Elevation Model (DEM) v01. Bioregional Assessment Source Dataset. Viewed 11 December 2018, http://data.bioregionalassessments.gov.au/dataset/12e0731d-96dd-49cc-aa21-ebfd65a3f67a.

A GIS polygon shapefile outlining the boundaries of the native input datasets used to construct a seamless, 2-meter resolution digital elevation model (DEM) was constructed for the open-coast region of the San Francisco Bay Area (outside of the Golden Gate Bridge), extending from Half Moon Bay to Bodega Head along the North-central California coastline. The goal was to integrate the most recent high-resolution bathymetric and topographic datasets available (for example, Light Detection and Ranging (lidar) topography, multibeam and single-beam sonar bathymetry) into a seamless surface model extending offshore at least 3 nautical miles and inland beyond the +20 m elevation contour.

The High Resolution Digital Elevation Model (HRDEM) product is derived from airborne LiDAR data (mainly in the south) and satellite images in the north. The complete coverage of the Canadian territory is gradually being established. It includes a Digital Terrain Model (DTM), a Digital Surface Model (DSM) and other derived data. For DTM datasets, derived data available are slope, aspect, shaded relief, color relief and color shaded relief maps and for DSM datasets, derived data available are shaded relief, color relief and color shaded relief maps. The productive forest line is used to separate the northern and the southern parts of the country. This line is approximate and may change based on requirements. In the southern part of the country (south of the productive forest line), DTM and DSM datasets are generated from airborne LiDAR data. They are offered at a 1 m or 2 m resolution and projected to the UTM NAD83 (CSRS) coordinate system and the corresponding zones. The datasets at a 1 m resolution cover an area of 10 km x 10 km while datasets at a 2 m resolution cover an area of 20 km by 20 km. In the northern part of the country (north of the productive forest line), due to the low density of vegetation and infrastructure, only DSM datasets are generally generated. Most of these datasets have optical digital images as their source data. They are generated at a 2 m resolution using the Polar Stereographic North coordinate system referenced to WGS84 horizontal datum or UTM NAD83 (CSRS) coordinate system. Each dataset covers an area of 50 km by 50 km. For some locations in the north, DSM and DTM datasets can also be generated from airborne LiDAR data. In this case, these products will be generated with the same specifications as those generated from airborne LiDAR in the southern part of the country. The HRDEM product is referenced to the Canadian Geodetic Vertical Datum of 2013 (CGVD2013), which is now the reference standard for heights across Canada. Source data for HRDEM datasets is acquired through multiple projects with different partners. Since data is being acquired by project, there is no integration or edgematching done between projects. The tiles are aligned within each project. The product High Resolution Digital Elevation Model (HRDEM) is part of the CanElevation Series created in support to the National Elevation Data Strategy implemented by NRCan. Collaboration is a key factor to the success of the National Elevation Data Strategy. Refer to the “Supporting Document” section to access the list of the different partners including links to their respective data.

High resolution (1-2m spacing) digital elevation models (DEMs) covering portions of the state. The DEMs are derived from LIDAR data and depict the bare earth terrain in raster format. Multiple agencies (Federal, State, and County) provided the data. The DEMs can be downloaded through the NYS Orthos Online app (http://orthos.dhses.ny.gov/).

Digital elevation model (DEM) data are arrays of regularly spaced elevation values referenced horizontally either to a Universal Transverse Mercator (UTM) projection or to a geographic coordinate system. The grid cells are spaced at regular intervals along south to north profiles that are ordered from west to east. The U.S. Geological Survey (USGS) produces five primary types of elevation data:...

The USGS 3D Elevation Program (3DEP) Index service from The National Map shows two general categories of downloadable elevation data: (1) digital elevation model (DEM) datasets at standardized horizontal resolutions, and (2) elevation source data including that used to produce standard DEMs, and additional datasets derived from ifsar in Alaska only. Distributable DEM products include: 2 arc-second (in Alaska only); 1 arc-second; 1/3 arc-second; 1/9 arc-second; 5 meter (in Alaska only); and 1 meter. The 2-, 1-, and 1/3-arc-second products are staged for download in 1x1 degree tiles in ArcGrid, GridFloat, or IMG formats, while 1/9 arc-second products are staged in 15x15 minute tiles in IMG format only. The 5-meter products are staged for download in ArcGrid only as a single mosaicked raster to each project extent. The 1-meter products are staged in 10,000x10,000 meter tiles in IMG format only. Distributable elevation source data include: lidar point clouds (LPC) in LAS format for various parts of the U.S., and ifsar-derived digital surface models (DSM) and orthorectified radar images (ORI) in TIFF format in Alaska only. For additional information on the 3DEP, go to http://nationalmap.gov/3DEP/index.html.

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated bathymetric-topographic DEMs are used to support individual coastal States as part of the National Tsunami Hazard Mitigation Program's (NTHMP) efforts to improve community preparedness and hazard mitigation. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources including: NOAA; the U.S. Geological Survey (USGS); the Puget Sound Lidar Consortium (PSLC); and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical datum of NAVD 88 and horizontal datum of World Geodetic System 1984 geographic (WGS 84). Grid spacing for the DEM is 1/3 arc-second (~10 meters).

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual coastal States as part of the National Tsunami Hazard Mitigation Program's (NTHMP) efforts to improve community preparedness and hazard mitigation. These integrated bathymetric-topographic DEMs are used to support tsunami and coastal inundation mapping. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. National Ocean Service (NOS), the U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), the Federal Emergency Management Agency (FEMA), and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to various vertical and horizontal datums depending on the specific modeling requirements of each State. For specific datum information on each DEM, refer to the appropriate DEM documentation. Cell sizes also vary depending on the specification required by modelers in each State, but typically range from 8/15 arc-second (~16 meters) to 8 arc-seconds (~240 meters).

The SurfZone Digital Elevation Model (DEM) was produced in 2019. Combining LIDAR and near-shore multibeam SONAR Bathymetry elevation data, it is the best currently available Digital Elevation Model (DEM) covering the inter-tidal zone produced by the Environment Agency.

The EA SurfZone DEM 2019 is supplied as a tiled raster dataset in GeoTiff format. Each tile is 5km * 5km and aligned to the Ordinance Survey National Grid. Each pixel represents 2 metres spatial resolution on the ground and elevations are presented in metres to Ordinance Survey Great Britain using the OSGM'15 and OSTM'15 transformation models. Elevations are referenced to Newlyn except for the Isles of Scilly which is referenced to St Marys.

The SurfZone DEM was produced by using a bespoke feathering technique to smooth the overlaps between LIDAR and Bathymetric surveys to produce a merged surface. Where small gaps existed between the LIDAR and Bathymetric surveys these were interpolated using a bilinear interpolation technique.

Please refer to the metadata index catalgoues which show for any location which survey was used in the production of the SurfZone DEM. The Metadata Index Catalogue provides information about the source of the survey data used, either LIDAR or Bathymetry for any area as well as the surface type, coastal monitoring region, geoidal model and transformation models used.

All LIDAR data used in the production of the SurfZone DEM was surveyed by the Environment Agency. Bathymetry data was surveyed by the Environment Agency or sourced from the National Network of Regional Coastal Monitoring Programmes of England from the Channel Coastal Observatory (www.channelcoast.org) website. The National Network of Regional Coastal Monitoring Programmes of England comprises of 6 Regional Programmes. When re-using these data, you must use the copyright statements in the licence to acknowledge the individual regions when reusing this dataset.

This 30 Meter Digital Elevation Model (DEM) is a copy of the USGS 1:24,000 scale Level 2 DEMs for the State.

There are three quadrangles known be be Level 1 DEM data: Town Line Lake (q1925), Grand Portage (q1261) and Grand Portage OE N (q1161).