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DEM-Net Samples

Summary

Please note that the DEM tiles will be downloaded on first run if they are not present on the local system.

Elevation samples
GPX Samples
Dataset Samples

Elevation Samples

Get Elevation on SRTM_GL3 dataset from a location (lat/lng) :

// download missing DEM files if necessary
ElevationService.DownloadMissingFiles(DEMDataSet.SRTM_GL3, lat, lon);

// get elevation
GeoPoint point = ElevationService.GetPointElevation(lat, lon, DEMDataSet.SRTM_GL3);
double? elevation = point.Elevation;

Get Elevation from multiple locations at once :

This sample get elevations for all line/DEM intersections (it can return a LOT of points). The line can be generalized and return only points where elevation change is relevant AND keeping the local maximas.

IEnumerable<GeoPoint> geoPoints = ElevationService.GetPointsElevation(points, dataSet);

Get line elevation :

// Straight line crossing exactly Mt Ventoux peak
var elevationLine = GeometryService.ParseGeoPointAsGeometryLine(new GeoPoint(44.078873, 5.144899), new GeoPoint(44.225876, 5.351516));

// Download DEM tiles if necessary
ElevationService.DownloadMissingFiles(DEMDataSet.AW3D30, elevationLine.GetBoundingBox());

// Get line elevation : 1274 points !
var geoPoints = ElevationService.GetLineGeometryElevation(elevationLine, dataSet);

// Compute metrics (to get distance from origin)
var metrics = geoPoints.ComputeMetrics();

// Simplify line with 50m resolution
var simplified = DouglasPeucker.DouglasPeuckerReduction(geoPoints.ToList(), 50 /* meters */);

//
// Now we have only 20 points but all the peaks and coves
//

GPX Samples

Get elevations for a GPX track

// Read GPX points and flatten the segments into a list of points
var gpxFile = Path.Combine("SampleData", "lauzannier.gpx");
var points = GpxImport.ReadGPX_Segments(gpxFile)
                      .SelectMany(segment => segment);

 // Retrieve elevation for each point on DEM
List<GeoPoint> gpxPointsElevated = ElevationService.GetPointsElevation(points, DEMDataSet.AW3D30)
                                        .ToList();

Dataset samples

A DEM.Net Dataset is a public data source of DEM files. DEM.Net supports global datasets in OpenTopography.org.

Get a report of all downloaded files

RasterService.GenerateReportAsString();

This will produce this nice output :

glTF 3D samples

DEMDataSet dataset = DEMDataSet.AW3D30;
var modelName = $"Montagne Sainte Victoire {dataset.Name}";

// You can get your boox from https://geojson.net/ (save as WKT)
string bboxWKT = "POLYGON((5.54888 43.519525, 5.61209 43.519525, 5.61209 43.565225, 5.54888 43.565225, 5.54888 43.519525))";
var bbox = GeometryService.GetBoundingBox(bboxWKT);
var heightMap = _elevationService.GetHeightMap(bbox, dataset)
		.ReprojectGeodeticToCartesian() // Reproject to 3857 (useful to get coordinates in meters)
		.ZScale(2f)                     // Elevation exageration
		.CenterOnOrigin();

// Triangulate height map
var mesh = _glTFService.GenerateTriangleMesh(heightMap);
var model = _glTFService.GenerateModel(mesh, modelName);

// Export Binary model file
_glTFService.Export(model, Directory.GetCurrentDirectory(), modelName, exportglTF: false, exportGLB: true);

This will run in less than 500ms and produce this nice model (you can natively open it in Windows 10's 3D viewer):

All elevations are linked together as a triangle mesh.

STL samples

Docs coming soon...

Imagery samples

Docs coming soon...

dem-net/Samples

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