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22 votes
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What is NASADEM and when it will be released?

NASADEM is a full reprocessing of the SRTM data using state-of-the-art interferometric processing techniques. It also improves accuracy, reduce gaps and improve the quality of the data used to fill ...
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  • 1,174
20 votes

Choosing DEM in France?

The answer is not as simple as the question may imply. If we had one "best one" we would not need the others, we would just use the best. Horses for courses though, needs matter. Saying that. This ...
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17 votes

Gdal: how to get the max and min altitudes of my topographic raster?

With Python, you can access raster statistics using the Python GDAL/OGR API. from osgeo import gdal # open raster and choose band to find min, max raster = r'C:\path\to\your\geotiff.tif' gtif = gdal....
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16 votes
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Gdal: how to get the max and min altitudes of my topographic raster?

With bash alone, you can use : gdalinfo -mm input.tif It returns a range of infos within which is the string Computed Min/Max=-425.000,8771.000, for my Eurasian raster. Some cleanup and you get your ...
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  • 2,553
16 votes

Producing smooth and consistent contour lines from SRTM

To smooth your contours it is the best way to smooth your DEM first. Here are some useful information: What raster smoothing/generalization tools are available? I'm using SAGA GIS for this task. ...
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  • 4,184
15 votes
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Download new SRTM 30 meters

There is a new, 30 meters resolution SRTM DTM coming out. As stated on the NASA JPL official page, The next release is planned for later in 2014, and it is expected to include all of South America ...
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  • 4,398
14 votes
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Remove border lines of SRTM tiles rendered as hillshade

SRTM tiles (3601 px * 3601 px in this case) have 1-pixel overlaps in between. When you apply transparency (or reduced opacity) to your hillshade layer, such overlapping pixels stand out. You may have ...
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  • 29k
9 votes
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Why are poles missing from GIS topographic data?

SRTM (Shuttle Radar Topography Mission) was a shuttle mission, no satellite involved. But essentially the satellites do not cross the poles. In a sun-synchronous orbit, which most imaging satellites ...
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8 votes

Download new SRTM 30 meters

I answered a similar question here You can download and clip a portion of the SRTM 30m DEM with one command with the elevation Python command line tool. Install it and perform the self ...
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  • 271
8 votes
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Why do "stripes" appear on raster?

The resampling method 'near' or 'nearest' is generally to be considered only for succinct/classified data, it attempts to assign a cell value based on the closest source pixel: This is most commonly ...
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7 votes
Accepted

Delineating large scale watershed?

I have a tremendous respect for GRASS and the r.tarraflow algorithm and I'm sure that given enough effort, you would be able to make it work for this application. But as an alternative, I develop a ...
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  • 10.8k
7 votes
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SRTM v4 hillshade very grainly surface

This is a fairly common problem to run into. My guess is that your SRTM data are still in geographical coordinates and has not been reprojected. As such, the elevation units are being measured in ...
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  • 10.8k
7 votes

Downloading SRTM data

You can download and clip a portion of the SRTM 30m DEM with one command with the elevation Python command line tool. Install it and perform the self check with: $ pip install elevation Check if ...
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  • 271
7 votes

Extracting elevation from .HGT file?

GDAL can read/write these raster formats with the SRTMHGT driver. This means you can view the raster with QGIS, ArcGIS, or use GDAL utilities like gdallocationinfo to get values from a point, e.g.: ...
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  • 39.7k
7 votes
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Which is better for measuring actual ground elevation, NED or SRTM?

This is by no means an answer to your specific problem but an explanation of elevation data and vertical accuracy. Also, this all wouldn't fit in a comment. Only a select number (depending of area ...
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  • 5,727
7 votes
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Extracting flat areas and saving them as lakes using QGIS?

You need to extract the slope first from the DEM using the Raster -> Terrain Analysis -> Slope OR Raster -> Analysis -> DEM (Terrain Models). Then use the slope raster to extract the lakes ...
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  • 36.2k
6 votes
Accepted

Does a SRTM DEM image show details such as fields?

Chris, Your confusion stems from the distinction between the image represented by image 1 (a true color image) and the DEM you downloaded. The two are very different things and this distinction is ...
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  • 826
6 votes
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Use "SRTM Downloader Plugin" with "QGIS 3.4"

I have tested the plugin and it is working fine in my machine. One common way to download (SRTM among other) data is searching it in Earth Explorer site. All the information about how to use the ...
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5 votes

Gdal: how to get the max and min altitudes of my topographic raster?

If the stats have already been calculated: gdalinfo input.tif If they haven't been calculated yet, do: gdal_translate -stats input.tif output.tif gdalinfo output.tif
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5 votes
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Removing no data area (sea) from raster in ArcMap?

If you go to Symbology under Layer Properties of your image, there is an option to Display Background Values. You can choose 'No Color' and that should remove the black sea part.
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  • 6,876
5 votes

Elevation value (in meters) from SRTM

SRTM data are distributed in a few common formats including *.hgt files, the DTED format, and the more common *.tif file format. Both of these are raster formats and the elevation values are stored ...
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  • 10.8k
5 votes
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artifacts in SRTM contour layers processed with GDAL tools and rendered with mapnik?

Here was my problem: No way the SRTM data is that messed up. The SRTM data IS that messed up. The warping above is actually in the DEMs in the SRTM3 dataset (downloaded from http://dds.cr.usgs.gov)...
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5 votes

Bad SRTM files?

You might try the USGS SRTM FTP site. I can assure you that each of the tiles you list as examples are there in their proper .hgt format and there are no suspicious files in the associated zip file. ...
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  • 10.8k
5 votes

Does a SRTM DEM image show details such as fields?

In the text there is basically an error in that there should be another sub heading between the SRTM data download section and the imagery download section. We provide a methodology for obtaining SRTM ...
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5 votes
Accepted

SAGA tool 'Relative Heights and Slope Positions' - What do results tell me?

Now, the answer from the developers of the tool, who kindly allowed me to forward the answer here. I translate and do my best to reproduce what I learnt from Dr. Conrad: The only expected input-...
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  • 141
5 votes

Choosing DEM in France?

As "@user two seven two three nine" says, it depends on what you are trying to do. For the geosciences, there are a number of relevant papers in "Elevation Models for Geoscience", Geological Society ...
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  • 1,214
4 votes

Basic question about downloading SRTM 3 arc resolution data

I recently wrote an SRTM download tool that works from the free and open-source GIS, Whitebox Geospatial Analysis Tools (which can be downloaded here). The user simply specifies the range of lat/long ...
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  • 10.8k
4 votes

SRTM vs Google Earth Pro elevation data

Both are the same. Google Earth uses the SRTM elevation data according to this topic on the Google Earth Help Forum: The global terrain dataset is 90M SRTM It says the same thing on Wikipedia: ...
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  • 985
4 votes
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Looking for good quality DEMs for Svalbard and Faroe Islands

The amazing ArcticDEM project has 2m and 5m coverage for much of the arctic, some of it available as time series. Not all of the data has been processed yet, but it looks like they have coverage of ...
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  • 12.3k
4 votes

How can get correct elevation values from Digital elevation models

It's impossible to pinpoint what is going on without looking at the data per se, but a wild guess would be due to the DEM being a DSM and not a DTM. I don't know how well you know these terms, but on ...
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