This collection is a legacy product that is no longer supported. It may not meet current government standards. The Canadian Digital Elevation Model (CDEM) is part of Natural Resources Canada's altimetry system designed to better meet the users' needs for elevation data and products. The CDEM stems from the existing Canadian Digital Elevation Data (CDED). In these data, elevations can be either ground or reflective surface elevations. A CDEM mosaic can be obtained for a pre-defined or user-defined extent. The coverage and resolution of a mosaic varies according to latitude and to the extent of the requested area. Derived products such as slope, shaded relief and colour shaded relief maps can also be generated on demand by using the Geospatial-Data Extraction tool. Data can then be saved in many formats. The pre-packaged GeoTiff datasets are based on the National Topographic System of Canada (NTS) at the 1:250 000 scale; the NTS index file is available in the Resources section in many formats.

This 8m Digital Elevation Model (DEM) was originally created by Geographx (geographx.co.nz) and was primarily derived from January 2012 LINZ Topo50 20m contours (data.linz.govt.nz/layer/768).

Suitable for cartographic visualisation only. It was created by the interpolation of 20m contours with post-processing and filtering it is not suitable for terrain analysis.

Spatial accuracy is nominally the same as for the LINZ source data: 90% of well-defined points are within ±22 metres horizontally and within ±10 metres vertically.

For a full description of the how the DEM was generated refer to this layer’s metadata.

Digital model of elevations of Aragon, obtained from the ascii MDT files of the 2015 PNOA of 0.5 meters of resolution provided by the National Geographical Institute. The information is presented in raster format, adapted to its exploitation by means of geographic information systems (GIS). Digital model of elevations of Aragon, obtained from the ascii MDT files of the 2015 PNOA of 0.5 meters of resolution provided by the National Geographical Institute. The information is presented in raster format, adapted to its exploitation by means of geographic information systems (GIS).

The Terrain Ruggedness Index (TRI) is used to express the amount of elevation difference between adjacent cells of a DEM. This raster function template is used to generate a visual representation of the TRI with your elevation data. The results are interpreted as follows:0-80m is considered to represent a level terrain surface81-116m represents a nearly level surface117-161m represents a slightly rugged surface162-239m represents an intermediately rugged surface240-497m represents a moderately rugged surface498-958m represents a highly rugged surface959-4367m represents an extremely rugged surfaceWhen to use this raster function templateThe main value of this measurement is that it gives a relatively accurate view of the vertical change taking place in the terrain model from cell to cell. The TRI provides data on the relative change in height of the hillslope (rise), such as the side of a canyon.How to use this raster function templateIn ArcGIS Pro, search ArcGIS Living Atlas for raster function templates to apply them to your imagery layer. You can also download the raster function template, attach it to a mosaic dataset, and publish it as an image service. The output is a visual TRI representation of your imagery. This index supports elevation data.References:Raster functionsApplicable geographiesThe index is a standard index which is designed to work globally.

The U.S. Geological Survey (USGS), in cooperation with the Illinois Center for Transportation and the Illinois Department of Transportation, prepared hydro-conditioned geographic information systems (GIS) layers for use in the Illinois StreamStats application. These data were used to delineate drainage basins and compute basin characteristics for updated peak flow and flow duration regression equations for Illinois. This dataset consists of raster grid files for elevation (dem), flow accumulation (fac), flow direction (fdr), and stream definition (str900) for each 8-digit Hydrologic Unit Code (HUC) area in Illinois merged into a single dataset. There are 51 full or partial HUC 8s represented by this data set: 04040002, 05120108, 05120109, 05120111, 05120112, 05120113, 05120114, 05120115, 05140202, 05140203, 05140204, 05140206, 07060005, 07080101, 07080104, 07090001, 07090002, 07090003, 07090004, 07090005, 07090006, 07090007, 07110001, 07110004, 07110009, 07120001, 07120002, 071200 ...

The 5m DEM is derived from the LiDAR2019B dataset (consisting of the 2018, 2019A and 2019B datasets). The 5m DEM has a vertical accuracy of 30cm. The height reference used is the SA Land Levelling Datum and the SAGEOID2010 was employed.The City of Cape Town Ground Level Map 2019 is defined in the City of Cape Town Municipal Planning Amendment By-law, 2019 as: “‘City of Cape Town Ground Level Map’ means a map approved in terms of the development management scheme, indicating the existing ground level based on floating point raster’s and a contour dataset from LiDAR information available to the City”. The Ground Level Map was approved by the City Council on the 27th July 2023.All Raster Image Services (REST):https://cityimg.capetown.gov.za/erdas-iws/esri/GeoSpatial%20Datasets/rest/services/All Raster Image Services (WMS):Use URL below to add WMS Server Connection in ArcGIS Desktop, ArcPro, QGIS, AutoCAD, etc.https://cityimg.capetown.gov.za/erdas-iws/ogc/wms/GeoSpatial Datasets?service=WMS&request=getcapabilities&For a copy or subset of this dataset, please contact the City Maps Office: city.maps@capetown.gov.zaCCT Ground Level Map: ‘How to Access’ Guide – External Users: CCT Ground Level Map: ‘How to Access’ Guide – External Users | Open Data Portal (arcgis.com)Geomatics Ground Level Map Explainer: Geomatics Ground Level Map Explainer | Open Data Portal (arcgis.com)Land Use Management Ground Level Map Explainer: Land Use Management Ground Level Map Explainer | Open Data Portal (arcgis.com)

A map service layer (map image layer) containing hydro-corrected drainage basin, watershed, catchment and sub-basin boundaries for drainage areas that impact Tallahassee and Leon County, Florida. This map service was generated from the most recent digital elevation model of Leon County, Florida. LAYERSBasins: Local level basins are the largest drainage unit tracked by Tallahassee-Leon County government and reflect final destinations of surface water drainage. Lake Jackson is, for example, a natural lake where a substantial amount of surface water runoff ultimately collects. Ames Sink (Lake Munson Basin) is a natural swallet (a sinkhole where surface water enters the aquifer) where surface watercourses terminate into the Floridan Aquifer. Lake Miccosukee is a water feature in part created from infrastructure that controls water elevation (weir/spillway) and a berm that prevents the surface water from draining into the aquifer by way of a swallet. Watersheds: Watersheds are groups of catchments aggregated (merged) to produce even larger more meaningful drainage units. The results are produced from storm-water inventory wherever possible and indicate where water ultimately collects. This could be a much larger storm-water facility, a natural area (lake or depression) or other area where a greater volume of surface water collects. Catchments: Catchments are an aggregated set of data. Meaning groups of sub-basins (deranged areas) are merged to create larger more meaningful boundary areas. For natural areas this could be several shallow depressions being included with a larger nearby natural feature (lake, sink, etc.). Meaning depending upon rainfall conditions an entire area of interconnected lower elevation depressions coalesce into a larger drainage area. For developed areas, this could mean a series inlets direct surface drainage by way of conduits to a storm-water management facility. This information is processed by either known inventory data connection or by best assumption. Sub-Basins: The sub-basin features are identical geometry to the ‘deranged area’ boundaries produced by Archydro, an extension of ESRI ArcGIS software. The deranged area boundaries used to produce the sub-basins are themselves produced by hydro-correcting the DEM surface to reflect both natural environments and areas with human activity. Areas with more substantial human activity effect the drainage pattern of water and in particular storm-water runoff. This would include things like paved roads, paved parking lots and buildings. An effort has been made to produce deranged area boundaries at locations where storm-water runoff is directed (inlets, grates, storm-water ponds, etc.) and as well natural locations in the environment (sinks, depressions, confluences, etc.). Hydro-correcting involves a certain amount of modification and manipulation of the DEM surface to produce better results. For example, ‘burning’ in a channelized ditch along a road with many driveway aprons that obscure the subsurface ditch (driveway culverts) beneath. A deranged area boundary is created by leveling an area that approximates where the water would flow (inlet, pond, sinkhole, etc.) by way of gravity and infrastructure that directs it (ditches, curbs, etc.). From the leveled area the ArcHydro software uses the DEM to generate the drainage boundary (deranged area boundary) using the DEM surface. DETAILSProject SummaryESRI’s Arc Hydro toolset was used to “hydro-correct” a high-fidelity Lidar-derived bare earth DEM for the purpose of mapping all drainage areas that contribute water to Leon County. This process allowed for the mapping of actual surface drainage patterns on the ground, including natural areas of unaltered drainage along with areas where surface drainage has been engineered to not follow the natural topography. This process yielded a much more accurate delineation of the amount of water draining to a given location than would otherwise be possible using topographic DEMs alone. Since one of the goals of the project was to map all drainage areas that contribute surface drainage to Leon County, the mapping area extends beyond Leon County to include an additional nine counties in Florida and Georgia. This effort marked the first time that all areas that contribute surface drainage to Leon County were mapped. Hydro-CorrectionHydro-correction methods were used to modify the DEMs in order to take into account the presence of stormwater inventory. For this dataset, hydro-correction was accomplished by using 3 geoprocessing tools from the Arc Hydro toolset: Build Walls: The Build Wall tool allows the user to superimpose a polyline on an input DEM to raise the elevation values in the output DEM by a user-specified amount. This tool was primarily used where drainage divides were not well expressed in the source DEM. Additionally it was used to force drainage to stop at a particular point of interest (such as a stream confluence). DEM Reconditioning: This tool allows the user to superimpose a polyline on an input DEM to reduce the elevation values in the output DEM by a user-specified amount. This is often referred to as “burning” and is the opposite of Build Walls. Level DEM: This tool allows the user to superimpose a polygon on an input DEM to reassign cell values in the output DEM to a constant user-specified elevation. This tool was used to create pour point locations in the output DEM by reassigning the output elevation to be slightly lower than the surrounding input pixel values, thereby creating a “pit” in the output DEM. The area that drains to each “pit” is referred to as a Sub-Basin. Drainage Area Delineation The Arc Hydro tool Sink Evaluation uses the 3 hydro-correction feature classes, the pour point feature class and the base earth DEM to create the drainage areas. Four feature classes representing drainage areas were produced: Sub-basins, Catchments, Watersheds, and Drainage basins. Sub-basins represent the smallest units of coherent drainage that were mapped. The Sub-Basins were the “building blocks” for creating a nested hierarchy of drainage units that are designed to be used at local scales as well as regional scales. The Sub-Basins were aggregated into larger nested drainage units, referred to as Catchments. The Catchments were aggregated into still larger nested drainage units, referred to as Watersheds. Finally, the Watersheds were aggregated into still larger nested drainage units, referred to as Drainage Basins. Drainage Boundary 3DDrainage Boundary 3D is a Polyline Z feature class created by intersecting the Sub-Basin boundaries with the DEM. The purpose of this feature class is to provide a set of metrics for identifying the high and low points along a Sub-Basin boundary, as well as pop-off locations for areas of closed drainage.