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  • Contours from NED in QGIS - "oversampled" NED?

    Contours from NED in QGIS - "oversampled" NED? January 5

    This question already has an answer here: What raster smoothing/generalization tools are available? 3 answers 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.

  • Defining and exporting a path from discrete points in QGISAugust 4

    I'm working with elevation data (NED, SRTM, etc.) in QGIS and I'm wondering how I might be able to pick a set of points from my map and export the coordinates to something like CSV. For example, I'd like to choose point A, then point B, C, and so for

  • Cesium terrain tiles too high by roughly 30mJuly 1

    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 roughly 30m. The Cesium AGI STK World Terrain set

  • Generating elevation 'database' from NED IMG dataJune 27

    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 the San Francisco Bay Area that I can look up with

  • Downloading NED Data: GridFloat versus IMG versus ESRI Grid (ArcGrid)May 5

    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 what purposes?

  • NED tiff files in ArcGISMarch 17

    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 the average elevation of each polygon from the tiff

  • Resolution of NED (National Elevation Dataset)November 6

    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 measured the dimensions of the area covered by differ

  • Does the NED use geocentric or geodetic latitude?

    Does the NED use geocentric or geodetic latitude?July 23

    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 in the documentation that comes with the data I dow

  • How to read out the geoPDF data downloaded from USGS ned database?March 26

    How do I read the GeoPDF data that I download from the National elevation database from USGS? All I am looking for is lat/long/height for each point as much as the resolution would allow for a specific area in the map. Are there ways to get this data

  • qgis2 slope analysis from NED data gives crazy histogram

    qgis2 slope analysis from NED data gives crazy histogramDecember 7

    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 one big valley in the middle: Here's the initial

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