This image service is available through CTECO, a partnership between UConn CLEAR and CT DEEP. This layer is a hydro-flattened bare earth digital elevation model (DEM) derived from the classified Lidar point cloud covering the state of Connecticut.NOTE Service ChangesAlthough currently displaying 2023 elevation, this service (called Elevation) previously displayed 2016 elevation and will be updated when new elevation is available. Visit the CT ECO Map and Image Services page for a complete list of available elevation services. Connect to this service when you always want the latest and greatest service. Connect to CT 2023 Elevation (DEM) service for 2023 elevation that will not change. 2023 Statewide Extent: ConnecticutDates: 2023 (March 27 - April 13), between snow melt and leaf outData Info: statewide Digital Elevation Model (DEM), which is a bare earth elevation raster with no functions applied Pixel Resolution: 2 foot DEM raster derived from QL1+ Lidar point cloud with a minimum of 15 points per square meter inland and 20 points per square meter along the coast. The bare earth elevation from the points were averaged to get the elevation value for each pixel in the DEM. Projection: CT State Plane NAD 83 (2011) Feet (EPSG 6434)Service Projection: WGS 1984 Web Mercator Auxiliary Sphere (EPSG 3857)More Information- All About the 2023 Data Collection (Imagery and Lidar)- All about Connecticut Lidar Elevation- Lidar Elevation on CT ECO Explained- Metadata xml format- Download DEM and pointsTips- The elevation service contains processing templates like hillshade, slope, and aspect, that can be applied to change the appearance of the layer. - Symbology is another useful and easy way to display the elevation differently. Credit and Funding

This image service is available through CTECO, a partnership between UConn CLEAR and CT DEEP. This layer is a hydro-flattened bare earth digital elevation model (DEM) derived from the classified Lidar point cloud covering the state of Connecticut.

NYC 1foot Digital Elevation Model: A bare-earth, hydro-flattened, digital-elevation surface model derived from 2010 Light Detection and Ranging (LiDAR) data. Surface models are raster representations derived by interpolating the LiDAR point data to produce a seamless gridded elevation data set. A Digital Elevation Model (DEM) is a surface model generated from the LiDAR returns that correspond to the ground with all buildings, trees and other above ground features removed. The cell values represent the elevation of the ground relative to sea level. The DEM was generated by interpolating the LiDAR ground points to create a 1 foot resolution seamless surface. Cell values correspond to the ground elevation value (feet) above sea level. A proprietary approach to surface model generation was developed that reduced spurious elevation values in areas where there were no LiDAR returns, primarily beneath buildings and over water. This was combined with a detailed manual QA/QC process, with emphasis on accurate representation of docks and bare-earth within 2000ft of the water bodies surrounding each of the five boroughs. Please see the following link for additional documentation- https://github.com/CityOfNewYork/nyc-geo-metadata/blob/master/Metadata/Metadata_DigitalElevationModel.md

This image service is available through CTECO, a partnership between UConn CLEAR and CT DEEP. This layer is a hydro-flattened bare earth digital elevation model (DEM) derived from the classified Lidar point cloud covering the state of Connecticut.

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 (NAD83). All bare earth elevation values are in meters and are referenced to the North American Vertical Datum of 1988 (NAVD88). Each tile is distributed in the UTM Zone in which it lies. If a tile crosses two UTM zones, it is delivered in both zones. The one-meter DEM is the highest resolution standard DEM offered in the 3DEP product suite. Other 3DEP products are nationally seamless DEMs in resolutions of 1/3, 1, and 2 arc seconds. 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 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.

A bare-earth, hydro-flattened, digital-elevation surface model derived from 2010 Light Detection and Ranging (LiDAR) data. Surface models are raster representations derived by interpolating the LiDAR point data to produce a seamless gridded elevation data set. A Digital Elevation Model (DEM) is a surface model generated from the LiDAR returns that correspond to the ground with all buildings, trees and other above ground features removed. The cell values represent the elevation of the ground relative to sea level. The DEM was generated by interpolating the LiDAR ground points to create a 1 foot resolution seamless surface. Cell values correspond to the ground elevation value (feet) above sea level. A proprietary approach to surface model generation was developed that reduced spurious elevation values in areas where there were no LiDAR returns, primarily beneath buildings and over water. This was combined with a detailed manual QA/QC process, with emphasis on accurate representation of docks and bare-earth within 2000ft of the water bodies surrounding each of the five boroughs.

Unmanned Aerial System (UAS) flights were conducted over four stream catchments in Rio Blanco County, Colorado, during the summer of 2016. Two sties had active oil and gas operations within the basin whereas the other two sites did not. Structure from motion (SfM) was used to align raw images and create a dense point cloud, georectified orthoimage, and Digital Elevation Model (DEM) for each basin. A Digital Terrain Model (DTM), or bare earth model, for each basin was created by reclassifying the dense point cloud as either bare ground or other (vegetation, oil and gas infrastructure, etc.) and interpolating the land surface between bare ground points. Ideally, the DTM would always be equal or lower than the DEM; however, the interpolated surface can sometimes be higher than the DEM if bare ground points surround depressions with vegetation or in thick vegetation strands with an undulating surface. Therefore, a final surface model, created by merging the DTM with the DEM for all areas where the DTM was greater than the DEM, was produced for each basin. Lastly, a random forest classification approach was used to classify the orthoimagery on a pixel level into five vegetation/land cover classifications - bare ground, grass, litter, shrub/woody vegetation, and shadow.

Unmanned Aerial System (UAS) flights were conducted over four stream catchments in Rio Blanco County, Colorado, during the summer of 2016. Two sties had active oil and gas operations within the basin whereas the other two sites did not. Structure from motion (SfM) was used to align raw images and create a dense point cloud, georectified orthoimage, and Digital Elevation Model (DEM) for each basin. A Digital Terrain Model (DTM), or bare earth model, for each basin was created by reclassifying the dense point cloud as either bare ground or other (vegetation, oil and gas infrastructure, etc.) and interpolating the land surface between bare ground points. Ideally, the DTM would always be equal or lower than the DEM; however, the interpolated surface can sometimes be higher than the DEM if bare ground points surround depressions with vegetation or in thick vegetation strands with an undulating surface. Therefore, a final surface model, created by merging the DTM with the DEM for all areas where the DTM was greater than the DEM, was produced for each basin. Lastly, a random forest classification approach was used to classify the orthoimagery on a pixel level into five vegetation/land cover classifications - bare ground, grass, litter, shrub/woody vegetation, and shadow.

This resource contains Lidar-DEM collection status shapefiles from the Texas Natural Resources Information System (TNRIS) [http://tnris.org]. November 2023 updates: this year, TNRIS changed its name to Texas Geographic Information Office (TxGIO). The domain name hasn't changed yet, but the data hub is continually evolving. See [1], [2] for current downloadable data.

For purposes of Hurricane Harvey studies, the 1-m DEM for Harris County (2008) has also been uploaded here as a set of 4 zipfiles containing the DEM in tiff files. See [1] for a link to the current elevation status map and downloadable DEMs.
Project name: H-GAC 2008 1m Datasets: 1m Point Cloud, 1M Hydro-Enforced DEM, 3D Breaklines, 1ft and 5ft Contours Points per sq meter: 1 Total area: 3678.56 sq miles Source: Houston-Galveston Area Council (H-GAC) Acquired by: Merrick, QA/QC: Merrick Catalog: houston-galveston-area-council-h-gac-2008-lidar

References: [1] TNRIS/TxGIO StratMap elevation data [https://tnris.org/stratmap/elevation-lidar/] [2] TNRIS/TxGIO DataHub [https://data.tnris.org/]

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 GEODATA 9 Second DEM (DEM-9S) Version 3 is a grid of ground level elevation points covering the whole of Australia, with a grid spacing of 9 seconds in longitude and latitude (approximately 250 metres) in the GDA94 coordinate system. The 9 Second Flow Direction Grid (D8-9S) is a corresponding grid describing the principal directions of surface drainage across the whole of Australia.

Version 3 of the DEM-9S was calculated by Version 5.2.2 of the ANUDEM procedure (Hutchinson 2007) from comprehensively revised and augmented national GEODATA TOPO-250K (TOPO-250K) topographic source data (AUSLIG 1992, Geoscience Australia 2003, Geoscience Australia 2006). The

source data included revised versions of TOPO-250K elevation points, streamlines, cliff lines and waterbodies, trigonometric points from the National Geodetic Database and additional elevation, streamline and sink point data digitised by the Fenner School from 1:100K source material. Version

5.2.2 of the ANUDEM procedure incorporates major upgrades to the modelling of streamlines, lakes, cliff lines and the coastline.

The 9 Second Flow Direction Grid (D8-9S) has been released for the first time, with Version 3. This grid was calculated by the ANUDEM procedure as it calculated the DEM-9S. It incorporates the data streamline structure and describes the drainage structure continent-wide. It can be used to delineate

streamlines and associated catchment boundaries for the DEM-9S. This is particularly useful in low relief areas where drainage structure is not reliably defined by the DEM elevations alone.

The comprehensive revisions and additions to the source data for the DEM-9S Version 3 were completed over a period of 3 years by the Fenner School and Geoscience Australia. This built on the substantial period of source data revision and algorithmic development by the Fenner School over the last 15 years. Comprehensive quality assurance of the DEM-9S and the D8-9S was performed jointly by the Fenner School and Geoscience Australia. The revised version of the ANUDEM elevation gridding procedure was developed and implemented by Professor Michael Hutchinson of the Fenner School.

The DEM-9S Version 3 is a model of the terrain in which each data point represents the approximate elevation at the centre of each 9 second by 9 second cell. The density and positional accuracy of the source point elevation data generalises the local terrain, resulting in limited representation of some high

points. Version 3 incorporates the improvements made in Version 2 by including with the source data the national trigonometric points from the National Geodetic Data Base.

The representation of abrupt changes in landform has been comprehensively upgraded in Version 3 by incorporating, for the first time, the TOPO-250K national cliff line data and by upgrading the modelling of cliff lines by the ANUDEM procedure to minimise conflicts between streamlines and cliff lines. The

upgraded procedure maximises the accuracy of the representation of surface shape within the limits imposed by the 9 second grid spacing.

Of central importance for the accurate representation of surface drainage structure is the upgrading of the modelling of streamlines by ANUDEM. This improves the positional accuracy of streamlines and explicitly incorporates, also for the first time, the extensive distributary streamline networks that occur in low relief areas of the Australian continent. ANUDEM has also been upgraded to improve the positional accuracy of the coastline and to ensure a smooth transition between land and seabed away from areas with coastal cliffs.

Dataset History

Dataset history was not supplied with the original metadata. The following history was written by the Bioregional Assessment team.

See: Chapter 2 - "The Development of the 9 Second DEM" within the attached User Guide PDF.

* Early National Digital Elevation Models

* 9 Second DEM Version 1

* 9 Second DEM Version 2

* 9 Second DEM Version 3

This chapter recounts the development over the last three decades of national topographic data, and the associated development of the ANUDEM elevation gridding procedure, leading to the successive versions of the 9 Second DEM.

Further information can be found at http://www.ga.gov.au/metadata-gateway/metadata/record/66006/

Dataset Citation

Geoscience Australia (2008) GEODATA 9 second DEM and D8: Digital Elevation Model Version 3 and Flow Direction Grid 2008. Bioregional Assessment Source Dataset. Viewed 13 March 2019, http://data.bioregionalassessments.gov.au/dataset/ebcf6ca2-513a-4ec7-9323-73508c5d7b93.

This Digital Elevation Model (DEM) of the Vietnamese part of the Mekong delta was interpolated using almost 20.000 elevation points derived from a national topographical map of 2014 (scale 1:200,000). The elevation data is vertically referenced to the Vietnam's geodetic Hon Dau datum, which has its elevation origin at mean sea level (MSL) of the Hon Dau tide gauge. The DEM was interpolated from the topographical elevation points using empirical Bayesian kriging employing empirical data transformation and an exponential model. Elevation points with elevations higher than +10m, located on elevated bedrock outcrops were excluded from the interpolation. Rivers and bedrock outcrops were clipped from the final DEM. For more details on the elevation data, the interpolation procedure and data processing steps, see the corresponding paper and supplementary information.File name: Topo_DEM_Mekong_delta_excl_rivers_and_bedrock.ascFile format: ASCI fileSpatial reference: WGS_1984_UTM_Zone_48NVertical reference datum: Hon Dau datum (Vietnamese)Grid cell size: 500 x 500 m

This web map leverages the KyFromAbove 5 foot Digital Elevation Model (DEM) ArcGIS Server Image Service and provides a 5K tiling grid with embedded links for downloading individual DEM tiles from Phase 1, Phase 2 and Phase3 collection periods. Each of the Phase1 DEM tiles are provided in an ERDAS Imagine (IMG) format and is zipped up with its associated metadata file in XML format. Phase2 and Phase3 DEM tiles are provided in a GeoTIFF format. The Phase1 data resource was derived from the ground class within KyFromAbove point cloud data and has a 5-foot point spacing. The Phase2 and Phase3 data was derived from the ground class within KyFromAbove point cloud data and has a 2-foot point spacing. DEM data specifications adopted by the KyFromAbove Technical Advisory Committee can be found here. More information regarding this data resource can be found on the KyFromAbove website.

A global 1-km resolution land surface digital elevation model (DEM) derived from U.S. Geological Survey (USGS) 30 arc-second SRTM30 gridded DEM data created from the NASA Shuttle Radar Topography Mission (SRTM). GTOPO30 data are used for high latitudes where SRTM data are not available. For a grayscale hillshade image layer of this dataset, see "world_srtm30plus_dem1km_hillshade" in the distribution links listed in the metadata.

Underwater images collected near Dollar Point in Lake Tahoe, California, were processed using Structure-from-Motion (SfM) photogrammetry techniques into a classified 3D point cloud. The DEM was derived in Metashape (ver. 1.6.4) from the point cloud, but it excludes the 'high noise' class. The DEM data were output as a geoTIFF raster at 25-mm resolution.

This dataset is a digital elevation model (DEM) of the beach topography of Lake Superior at Minnesota Point, Duluth, Minnesota. The DEM has a 1-meter (m; 3.28084 foot [ft]) cell size and was created from a LAS dataset of terrestrial light detection and ranging (LiDAR) data with an average point spacing of 0.137 m (0.45 ft). LiDAR data were collected August 10, 2019 using a boat-mounted Optech ILRIS scanner and methodology similar to that described by Huizinga and Wagner (2019).

Hydrologically conditioned digital elevation model (DEM) generated from lidar data clipped to the Difficult Run watershed with a 500-m buffer in ArcGIS 10.3.1 (ESRI, Redlands, CA). The DEM was hydrologically corrected by breaching through pits with no downslope neighboring cells to force surface flow to continuously move downslope using Whitebox Geospatial Analysis Tools (Lindsay and Dhun 2015, Lindsay 2016). Pits that were not properly breached were manually adjusted using elevation information from the DEM and aerial imagery to locate culverts under roadways.

The U.S. Geological Survey’s StreamStats program is a publicly-accessible web application (https://streamstats.usgs.gov) that can be used to delineate drainage areas, compute basin characteristics, and estimate flow statistics for user-selected locations on streams. StreamStats services are typically implemented at the statewide or watershed scale (referred to as state or basin applications), and although the three core functionalities remain consistent, many states have implemented custom tools to address specific water-resources planning and management needs. In Massachusetts, a watershed-scale application for the Mystic River Basin was developed to support stakeholder efforts to address stormwater challenges in this highly urbanized basin. The Mystic River Basin stormwater functionality was developed by incorporating 1-meter resolution lidar-derived elevation data and municipal storm drain data to accurately represent urban topography and stormwater flow (that is, subsurface piped flow). In the Mystic River Basin application, users can view the network of stormwater pipes and inlets, delineate drainage areas derived from lidar topography and stormwater infrastructure, and compute land-use/land-cover basin characteristics. This data release contains the 1-meter resolution digital elevation model (DEM; dem.tif) and two datasets derived from the DEM that support on-the-fly watershed delineation in the StreamStats web application. The flow direction raster (fdr.tif) is a raster dataset that indicates the direction of flow out of each cell; if the cell contains a stormwater inlet, it is represented as a sink in the flow direction raster. The catchment raster (cat.tif) represents the drainage areas to stormwater inlets and to surface-water flowpaths within the basin. The flow direction and catchment rasters are used in conjunction with the stormwater network to determine the drainage area to a point of interest selected by the user in StreamStats. This point must lie on the stormwater network, at either an inlet, on a pipe, or on a surface-water flowpath. The delineation produced in StreamStats is the accumulation of all catchments draining to the point of interest. To describe the processing steps used to produce the DEM, fdr, and cat rasters published in this data release, the overall approach to developing the Mystic River Basin stormwater functionality is given in the associated metadata. Please note that the stormwater network, comprised of stormwater inlets, pipes, culverts, and surface flow, produced for this study is not available for publication due to sensitivity concerns. Inquiries about these data may be made to the point of contact provided in the metadata.

The digital elevation models (DEM) are 2 m resolution raster elevation products that were generated from the Ontario Classified Point Cloud (Imagery-Derived) data. The point clouds were created via a pixel-autocorrelation process from the stereo aerial photography of the Geospatial Ontario (GEO) imagery program. The DEM does not represent a full ‘bare-earth’ elevation surface. There are areas where there are very few points classified as ground and interpolation has occurred across the resulting voids. Points classified as ground have not been assessed for accuracy to determine if they represent true ground features. Some features are still raised above ground surface, such as larger buildings, larger forest stands and other raised features. This data is for geospatial tech specialists, and is used by government, municipalities, conservation authorities and the private sector for land use planning and environmental analysis.

Digital Elevation Model (DEM) dataset current as of 2006. This dataset, produced by the PAMAP Program, consists of a raster digital elevation model with a horizontal ground resolution of 3.2 feet. The model was constructed from PAMAP LiDAR (Light Detection and Ranging) elevation points. PAMAP data a.

The GEODATA 9 Second Digital Elevation Model (DEM-9S) Version 3 is a grid of ground level elevation points covering the whole of Australia with a grid spacing of 9 seconds in longitude and latitude (approximately 250 metres) in the GDA94 coordinate system.

Version 3 of the DEM-9S was calculated by Version 5.2.2 of the ANUDEM procedure (Hutchinson 2007) from comprehensively revised and augmented national GEODATA-250K topographic source data (AUSLIG 1992, Geoscience Australia 2003, Geoscience Australia 2006) using Version 5.2.2 of the ANUDEM elevation gridding procedure. The source data included revised versions of GEODATA-250K elevation points, streamlines, cliff lines and waterbodies, trigonometric points from the National Geodetic Database and additional elevation and sink point data digitised by the Fenner School from 1:100K source material. Version 5.2.2 of the ANUDEM procedure incorporates major upgrades to the modelling of streamlines, lakes, cliff lines and the coastline.

GEODATA 9 Second Flow Direction Grid (D8-9S) has been released for the first time with Version 3. The D8-9S is a corresponding grid describing the principal directions of surface drainage across the whole of Australia. This grid was calculated by the ANUDEM procedure as it derived the DEM-9S. It incorporates the data streamline structure and describes the drainage structure continent-wide. It can be used to delineate streamlines and associated catchment boundaries for the DEM-9S. This is particularly useful in low relief areas where drainage structure is not reliably defined by the DEM-9S elevations alone.

The product can be used for applications requiring accurate representation of absolute elevation values. The elevation of source data high points (hills or mountains) is well represented in Version 3. The 1:250,000 source scale of the elevation grid makes the product useful for national, State-wide and regional applications.

For more detailed information please refer to the User Guide below.

Product Information Coverage: Australia, excluding external territories Currency: 2008 Coordinates: Geographical Datum: Horizontal: GDA94; Vertical: AHD71 Available Formats ESRI ASCII Grid, ER Mapper Grid, ESRI Grid,
ERDAS Imagine Grid, ASCII XYZ Grid Medium: DVD-ROM (All formats available) or free online from Geophysical Archive Data Delivery System (as ER Mapper Grid only)

You can also purchase hard copies of Geoscience Australia data and other products at http://www.ga.gov.au/products-services/how-to-order-products/sales-centre.html