Questions tagged [ned]

The National Elevation Dataset (NED) is the primary elevation data product of the USGS.

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Where do I find the date for a specific NED raster?

I am looking at stream height and flooding. As there are seasonal differences in flood severity, knowing what month or general time of year of the image(s) is essential. I downloaded a 3m National ...
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149 views

Choosing UTM to NED Conversion method?

I am having GPS and SFM (Structure for motion) trajectory in UTM coordinates. I wanted to convert the both trajectory to NED (North East Down). Method 1 In First step: I converted the data from UTM -...
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60 views

BIL formatted elevation files from NED

Sorry this is a novice question. I am completely new to the GIS domain and inherited a parser that expects a .bil file to get elevation at latlon points. From what little documentation there was, it ...
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How can I project a raster DEM and not get serious distortion in the resulting DEM?

Please see this link to see a fine example of what I am dealing with. Distortion in projected raster My specific situation is that I have downloaded DEM data from the National Map (USA) and it comes ...
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110 views

Using Tissot's Indicatrix Validate Conversion to ECEF

When using NED & ECEF as CRS: https://www.mathworks.com/help/map/ref/ned2ecef.html?requestedDomain=true Am I should worry from getting 'classical' projection issues? For example when x,y are ...
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662 views

Perform Calculations in Cartesian Frame (NED/ECEF) Vs. Geodetic Frame

I'm recording robot's path (using INS) in Cartesian frame coordinates (x,y,z) relative to origin point. So essentially I've created NED coordinate system. Origin point has exact (in advance measured) ...
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920 views

Convert locations from ECEF NED (local coordinate system) to WGS 84 (global coordinate system)

I track relative positions to known fixed reference location (Lat/Lon/Alt on WGS 84). Which means Location_0 is the above reference location, and Location_i is something like (X,Y,Z) relative by ...
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595 views

NED (NAVD88) to WGS84 heights

I need to convert the 1/3 arc second DEM files from the NED into WGS84 ellipsoid heights. The documentation says that the NED is referenced to NAVD88. I've tried using gdalwarp as follows: gdalwarp ...
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176 views

Zonal Statistics with very large mosaic in ArcGIS

I have the complete National Elevation Dataset from USGS in over 3000 ArcGrid files (coming to almost 190 GB), and a polygon shapefile of Colorado counties. I'm trying to use ArcMap Zonal Statistics ...
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881 views

Which is better for measuring actual ground elevation, NED or SRTM?

I know that NED DEM layers are created using mainly Lidar point clouds and that the SRTM derives its data from shuttle-based radar. I have both of these loaded into QGIS and can see that over my study ...
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196 views

Contours from NED in QGIS — “oversampled” NED? [duplicate]

I have downloaded an IMG file of NED data from the USGS National Map elevation products site and I want to create a contour map using QGIS. The problem is, the NED raster is "oversampled". There are ...
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348 views

Cesium terrain tiles too high by roughly 30m

I'm using the NED 1/3 arc second data set to generate tiles to zoom level 15 for Cape Canaveral in Florida, and finding that the terrain looks accurate in appearance, but the elevation is too high by ...
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458 views

Generating elevation 'database' from NED IMG data

I'm starting to work with the NED 1/3 and 1/9 arc-second data. I've been using gdal in Python and QGIS to do some basic conversions of the raw .IMG data from USGS. My goal is to get elevation data of ...
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1k views

Downloading NED Data: GridFloat versus IMG versus ESRI Grid (ArcGrid)

What are the advantages/disadvantages of each of these three file types? They are all available as formats for downloading NED data from The National Map. Which should generally be downloaded for ...
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388 views

NED tiff files in ArcGIS

I am working with ArcGIS 10 and have some tiff elevation files (NED). I can load them into Arc GIS and can look at them, and the values seem OK. I also have some shapefiles polygons and want to get ...
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1answer
103 views

Resolution of NED (National Elevation Dataset)

I downloaded some DEMs from the USGS with a resolution of 1/3 degrees for different areas in the US. Now I am looking at the files and saw that all DEMs have the same number of columns and rows. I ...
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Does the NED use geocentric or geodetic latitude?

What kind of latitude does the National Elevation Dataset (NED) use? Geocentric or geodetic or something else? I can't find the information anywhere on their site (http://ned.usgs.gov/index.html) or ...
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778 views

Slope analysis from NED data gives crazy histogram? [duplicate]

I'm attempting a simple slope analysis in QGIS2 using the plugin at Raster -> Terrain Analysis -> Slope. The slope output layer has a very strange histogram, basically spikes at 0 and at 89.9098 with ...