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22 votes
Accepted

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 ...
Camilo Rada's user avatar
  • 1,219
19 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. ...
Stefan's user avatar
  • 4,424
15 votes
Accepted

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 ...
Kazuhito's user avatar
  • 31k
10 votes
Accepted

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 ...
ahmadhanb's user avatar
  • 41.1k
10 votes
Accepted

Blocky SRTM hillshade in QGIS

Your screenshot depicts the classic blocky "herringbone" pattern resulting from applying a Nearest Neighbor resampling to raster elevation data. The solution is to instead apply either a ...
Stu Smith's user avatar
  • 8,190
7 votes

Getting 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 ...
Roberto Ribeiro's user avatar
6 votes
Accepted

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 ...
Gabriel De Luca's user avatar
6 votes
Accepted

Creating color physical map using SRTM V2 GeoTIFF tiles in QGIS

The area around the Caspian Sea is below sea (ocean) level. Baku, capital of Azerbaijan, is 28m below sea level. So using one single color ramp applied to a Digital Elevation Model that represents ...
Babel's user avatar
  • 73.1k
5 votes

Least Cost Path Analysis in QGIS?

It seems you're mostly confused about how to define cost. I highly recommend this post by Amanda Briney on GIS Lounge, especially the Requirements for Least Cost Path Analysis section. Cost can be ...
csk's user avatar
  • 24.9k
5 votes
Accepted

How to compress DEM SRTM files?

You most probably do not want to compress DEM data with JPEG, that would be lossy and introduce weird steps in the data. Instead I recommend the DEFLATE compression. To improve the size savings you ...
bugmenot123's user avatar
  • 10.9k
5 votes

SRTM raster looks pixelated with hillshade style in QGIS when zooming in

Hillshade is only as good as the quality (resolution) of the underlying DEM. What you can do is changing the resampling mode from Nearest Neighbour (default) to Bilinear (recommended for elevation/...
Babel's user avatar
  • 73.1k
4 votes
Accepted

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 ...
dbaston's user avatar
  • 13.2k
4 votes

Remove border lines of SRTM tiles rendered as hillshade

As described by @Kazuhito, the tiles should be combined into a virtual raster. Their method is performed within QGIS. If you have a large number of tiles you may prefer to do this from the ...
Alex Hajnal's user avatar
4 votes

QGIS raster merge results in a black rectangle

The merge was not successful: towards the end of you log you can read: MemoryError I would assume (also looking at the shape of the output "map", and judging from the large amount of time it took) ...
RafDouglas C. Tommasi's user avatar
4 votes

gdal translate resampling -r flag has no effect?

Resampling applies when the gridding of the input file is different from the gridding in the new space (most of the time, a warped space due to reprojection). It also makes sense when the size of the ...
radouxju's user avatar
  • 49.8k
4 votes
Accepted

QGIS "Profile Tool" Plugin inaccurate reading

The SRTM DEM has a ground resolution of 30 meters (1 arc-second), see https://en.wikipedia.org/wiki/Shuttle_Radar_Topography_Mission#Highest_Resolution_Global_Release and references. So the elevation ...
til_b's user avatar
  • 5,154
4 votes

SRTM hillshade looks weird in QGIS

.hgt SRTM files are in a geographic coordinate system (WGS84 EPSG:4326). Reproject them to an appropriate projected coordinate system that uses metres as the horizontal unit. Alternatively, if you ...
user2856's user avatar
  • 67.1k
3 votes

Looking for good quality DEMs for Svalbard and Faroe Islands

There is a DEM that covers 83N to 83S at 1 arc-second (~30m) resolution called ASTER Global DEM. A good description is available at https://lpdaac.usgs.gov/dataset_discovery/aster/aster_products_table/...
BradHards's user avatar
  • 12.9k
3 votes
Accepted

Finding the lat/long bounds of a 1km square (for all of Europe)

You need to convert your lat-long bounding box into a bounding box in a projected coordinate system in metres. You then chop this up into 1,000 unit boxes, giving you kilometre squares. There are pan-...
Spacedman's user avatar
  • 65k
3 votes
Accepted

Selecting DEM that best determines shore line using ArcGIS Desktop?

In addition to the raster solution I provided, here's a vector solution. The first thing I did was to convert the vertices of the DEM1 and DEM2 lines to points. To convert to points, you can use ...
Fezter's user avatar
  • 21.9k
3 votes

Selecting DEM that best determines shore line using ArcGIS Desktop?

I tried replicating this using Spatial Analyst. Firstly, I created three lines in different feature classes (though they could be in the same feature class). Topo Line (blue) DEM 1 (red) DEM 2 (...
Fezter's user avatar
  • 21.9k
3 votes
Accepted

gdal and google earth (and my gps) not reporting the same value

From MIL-PRF-89020B (which includes SRTM requirements), Section 3.3.1.1.2, DTED1 absolute vertical accuracy is 30m (90% Linear Error, to MSL). DTED2 absolute vertical accuracy is 18m (Section 3.3.2.1....
BradHards's user avatar
  • 12.9k
3 votes

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

Using gdalinfo and jq you can get what you need in a succinct fashion. This assumes that band that has your min/max is the first one (change the index if not). gdalinfo -json -mm input.tif | jq ....
Marc Miles's user avatar
3 votes

Reconciling elevation difference between SRTM and old US Army map in Laos?

Elevation is measured using a vertical coordinate system (vertical datum), and this vertical coordinate system can differ even if your ground coordinate system (horizontal datum) is the same. There ...
radouxju's user avatar
  • 49.8k
3 votes
Accepted

How to convert a TIFF file to HGT file?

From the GDAL doc: The driver does support creating new files, but the input data must be exactly formatted as a SRTM-3 or SRTM-1 cell. That is the size, and bounds must be appropriate for a cell. ...
user2856's user avatar
  • 67.1k
3 votes
Accepted

SRTM Data tiles appear to be different scales

There's no scaling in the data. The values are elevation in metres. Your issue is that each tile has different statistics (min, max, mean, etc.) and QGIS is using those stats to rescale/stretch ...
user2856's user avatar
  • 67.1k
3 votes
Accepted

Getting unexpected DEM spatial resolution using ArcMap

As your DEM seems to be in a geographic CRS ( EPSG:4326 ; WGS84), the unit of measurement is in degrees, not in meters. So measurements of length do not make sense: your cellsize is 0.0002777 degrees. ...
Babel's user avatar
  • 73.1k
3 votes

SRTM elevation data download error QGIS

There's no SRTM data available above 60°N. See below screenshot of the SRTM product coverage map from USGS.
user2856's user avatar
  • 67.1k
2 votes

How to stop gdalwarp creating world-spanning outputs near the dateline?

As I was facing the same problem, I wrote a small shell script that finds out if the raster file crosses the dateline. If true, following option is added to gdalwarp: --config CENTER_LONG 180 This ...
pLumo's user avatar
  • 6,519
2 votes

Using SRTM Global DEM for Slope calculation

Global DEM parameters (where most of formulas are based on assumption of Euclidean space) can be derived efficiently using the EQUI7 GRID system (Bauer-Marschallinger et al. 2014). EQUI7 GRID splits ...
Tom Hengl's user avatar

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