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Questions tagged [srtm]

The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February of 2000. As of 2016, it is now almost universally available at 1-Arc Second resolution.

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1answer
36 views

Tips for mapping coastline geometry with SRTM raster

Working on a map that includes a bathymetry layer, SRTM data for hillshade, and an accurate coastline boundary edge. I noticed though that the pixel resolution of SRTM 90m resolution creates visible ...
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0answers
30 views

How to evaluate the hilliness of an area using SRTM data? [closed]

I want to evaluate the hilliness of an area (e.g. municipality) using SRTM data. I thought about just calculating the standard deviation of the raster cells but my gut feeling is that this approach ...
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1answer
70 views

SRTM/DEM 1m resolution (batymetri) to point [closed]

I have bathymetry data (1 huge data) = SRTM/DEM/FGDBRaster (0,9818m resolution pixel, floating, 32 bit, 45 GB size) and an alternative data (split into small pieces data) = same data but with 1m ...
5
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1answer
69 views

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

In QGIS I georeferenced a 1970 US Army contour map for part of southern Laos (20 m intervals) with the following indicated properties: Horizontal datum Indian datum 1960 Spheroid=Everest Verical ...
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1answer
132 views

Getting correct elevation from hgt file [closed]

When reading SRTM3 data from a .hgt file I get the wrong elevation of a specific latitude longitude and I can't see why. Maybe someone can see the problem ? My coordinate is near Lissabon in the sea ...
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0answers
45 views

Slope area calculations of Google Earth Engine

First maybe this approach is stupid or wrong, but I get what I want. I need areas of specific slope classes for larger areas. Here is my code // Load the SRTM image. var srtm = ee.Image('USGS/...
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0answers
177 views

gdal_warp with huge tif: integer overflow

I retrieved the SRTM 1" data and merged it in one huge tif. Now I want to warp it. It's working fine for low resolution (eg 5000, 1000, 500), but it doesn't for 90m resolution. I'm using this command: ...
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0answers
64 views

gdal: apply orthorectification to ogr dataset

I'm trying to process Digital Globe L2A image with gdal utilities (e. g. this one: https://www.digitalglobe.com/resources/product-samples/washington-dc-usa) I am using SRTM digital elevation model to ...
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0answers
31 views

Can SRTM preserve topological feature well?

There are studies on SRTM data vertical elevation accuracy, which seem to indicate that there are around an average of 5m vertical error when compared with a DEM derived from cartographic maps. ...
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184 views

Which DEM format is efficient .tiff or .hgt

I know this is a vague question, but I've no expertise in GIS world. I was building this terrain map for a game like simulation project that I'm invested in. Data accuracy is least or no concern, but ...
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87 views

Hillshade in QGIS 3: scale correction factor missing

Recently (ca. 2 weeks ago), I created a QGIS-Project (QGIS 3, Win 7 and 10) covering large parts of Eurasia as physical map, using hillshades created from SRTM-DEM with the Raster – Analysis – DEM (...
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1answer
62 views

What is the absolute vertical accuracy and the relative vertical accuracy of SRTM 1-arc second?

When I was looking for the accuracy values for the srtm dem, I found research papers trying to find out these values for its own selected area of study, some of them assume that the absolute value in ...
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1answer
38 views

r.viewshed output location

I'm very new on GRASS and trying to extract the viewshed of a SRTM HGT file. This is what I've done so far: (why I'm using GRASS command line this way is not in question. Please answer this same way) ...
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65 views

SRTM/ 90m DEM - slope calculations

I have a question relating to a comment in a closed discussion (Does a value in srtm dem file refer to the center or corner of a cell?). The comment was following: "When talking about any DEM, it's ...
0
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1answer
217 views

Please check code to read elevation data from HGT file

I'm trying to read elevation data from NASA HGT file. I've started from Extracting elevation from .HGT file? and have changed this code a little to keep it simple and to use 1-ARCSEC (30-meter) data ...
2
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0answers
148 views

GDAL merge of DEM data resulting in large black tiles, elevation min/max problem?

I am new to QGIS (former Arc user) and having trouble with the raster merge tool. I am merging 7 tiles of SRTM arc 1 data to cover a province in eastern Ecuador. Data is resulting in large areas of ...
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0answers
30 views

NetCDF: Start+count exceeds dimension bound (Crop SRTM files for GMT)

I would like to crop the 1-arc second SRTM dataset for usage with GMT. I'm interested in Southern Africa. When running WEST=-10 NORTH=10 EAST=70 SOUTH=-50 gdal_translate -co TILED=YES -of GMT -...
5
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1answer
888 views

Producing smooth and consistent contour lines from SRTM

I downloaded and merged together a set of SRTM imagery. I am not sure whether it is my workflow, the actual terrain in question or if the scale of the imagery is simply too large to obtain smooth ...
2
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1answer
104 views

Correctly scale topographic SRTM data in OSM

I am trying to create contour maps in OSM with scales of 1:50,000 and 1:250,000 using 30-meter NASA SRTM data from here. Examples of what I'm trying to achieve can be seen on LINZ NZ Contours 1:50k ...
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1answer
95 views

Calculate elevation from rgb from png created from qgis

I am using qgis to create a raster elevation image (png) from SRTM data. I need to create a png via qgis which I will then query to determine the rgb of particular pixels via php. How do I define a ...
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2answers
462 views

Converting vertical datum from WGS84 to EGM96 in ArcGIS Desktop?

I am comparing two different Digital Elevation Models SRTM (Datum: EGM96) Cartosat (Datum: WGS84) How to convert WGS84 to EGM96 in ArcGIS Desktop?
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1answer
97 views

How can get correct elevation values from Digital elevation models

I am a bit new to spatial data analysis. I am trying to analyse elevation data for a coastal (almost flat) city with the highest elevation of about 30m. I have DEMs from ASTER, SRTM, and a DSM from ...
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1answer
1k views

What is NASADEM and when it will be released?

I heard some time ago about a new global DEM called NASADEM that was going to be released in 2017, and promised to be the best global DEM to date. What exactly is NASADEM and when will it be available?...
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0answers
134 views

Generating HGT Files from SRTM 90m Digital Elevation Database v4.1?

This may be a really dumb question and I apologize if it is - this is pretty new to me. I'm using the HGT files from https://dds.cr.usgs.gov/srtm/version2_1/SRTM3/ with a program currently and want ...
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344 views

Preparing SRTM (hgt) for use in SAGA GIS?

I am trying to prepare a raster file which i could use with SAGA processing tools for hydrologic analysis in QGIS. I am using Win 7, 32 bit, QGIS 2.14.20 and SAGA 2.3.2 I downloaded the srtm file in ...
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0answers
50 views

DEM interpolation when re-projecting [closed]

Can there be some instances where it is necessary to interpolate DEM when re-projecting (e.g. SRTM from WGS84 to another projection)? My current understanding of interpolation tells me that one ...
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0answers
39 views

Different pixel size between SRTM raster and watershed calculation

I have a problem in GRASS : I am trying to draw a river on STRM 30m. My raster has 30m*30m pixel but when I lauch r.watershed the size of pixel used was much bigger(1km*1km)... An idea?
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2answers
41 views

How to create new raster from only the extreme scores of another raster? (Correcting errors in ASTER elevation data)

I'm fairly new to working with rasters. I found out that in my area the ASTER digital elevation data has a "bump" artifact in it, where there's a large (non existant in real life) bump in the ...
5
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1answer
410 views

Delineating coastal subbasins using SAGA GIS or GRASS in QGIS?

I'm having some problems trying to delineate watersheds using the SAGA watershed delineation tools in QGIS. I have a SRTM DEM (cell size 30 m) which I set the water cells to NULL values, following ...
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4answers
279 views

Looking for good quality DEMs for Svalbard and Faroe Islands

I'm trying to find Open Data DEMs for a couple of personal mapping projects, for the following areas:- Faroe Islands Svalbard (Longyearbyen) Ideally, with 100m resolution or better. I normally use ...
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1answer
268 views

Extracting flat areas and saving them as lakes using QGIS?

I would like to extract lakes and sea from a DEM (SRTM) and save them as a separate layer. Is this possible? I have tried to extract flat areas with the Raster Calculator, but that did not work.
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118 views

Which STRM resolution Srtm2Osm.exe uses?

The piece of program Srtm2Osm uses SRTM elevation model from NASA to produce countour lines in OSM format. Does it use the SRTM1 at 30m or SRTM3 at 90m?
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310 views

Reading SRTM30 Plus data with Python

From How to extract elevation from .HGT file? I know how to get the elevation from SRTM1 and SRTM3 files. But how to get elevation from SRTM30 Plus ftp://topex.ucsd.edu/pub/srtm30_plus/srtm30/data/ ? ...
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2answers
415 views

How to render relief shadows on my map?

I have my OSM data in a local server. I already done with the contour lines using Phyghtmap and achieve a good result. Now I'm trying to show the relief "shadows" like this beautiful map: I know it ...
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1answer
449 views

How to convert SRTM's Lat/Lon to Landsat's utm reference system in GDAL?

SRTM data is given in Lat/Lon coordinates, while Landsat is given in UTM coordinates. Is there a way to reproject the SRTM data into the Landsat CRS in GDAL (Python)?
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145 views

Filling SRTM 1-arc second V4 voids using SRTM 1-arc second V3 with different resolution

I want to fill voids in the SRTM 1-arc second V4 (resolution 30m) DEM for Europe. Is it possible to directly fill the voids using SRTM 1-arc second V3 (resolution 90m) without resampling it to 30m ...
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305 views

Filling voids in DEM SRTM 1-arc second using QGIS by resampling and inserting another DEM

I'd like to use the DEM SRTM 1-arc second (Version 4, 30m) from USGS for Europe. Unfortunately there are some voids. My idea is to fill those voids using the void-filled version 3 (90m) by resampling ...
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2answers
87 views

Creating DEM using ArcGIS Desktop?

I am new in this field and I am having a problem with my DEM, (SRTM 30M). When I calculate flow accumulation a straight line appears if I fill the DEM. And rivers are not connected if I don't fill ...
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0answers
243 views

Where can I download the complete set of 90 meter elevation data?

I'm looking for .hgt files in bulk download for the complete 90M set. I need them in hgt format. Where can those be downloaded? I got the 27GB file at this link below but then realized it was not in ...
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1answer
124 views

Working with SRTM DEM that has rectangular cells?

I am trying to work with the 1 arc second resolution SRTM DEM from USGS's Earth Explorer, with eventual goals of filling its no data areas with an ASTER grid (also of 1 second resolution). I have an ...
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0answers
86 views

Converting raster into geostatistical layer? [closed]

I have downloaded a raster surface (SRTM) with pixel size equals to 30*30, and I want to use that surface as a geostatistical layer for further analysis. Is there any available tool that converts ...
2
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2answers
88 views

Selecting DEM that best determines shore line using ArcGIS Desktop?

I want to extract the shore line (Z=0) from DEM files. the earth explorer provides two DEM sources (ASTER & SRTM). In the following figure if the blue line represents the shore line as digitized ...
3
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1answer
234 views

SRTM mosaic elevations

My SRTM tiles have their elevations ranging from sea level i.e. 0m to 5,300m in Tanzania. My problem is that when I mosaic any two or more tiles, the elevation displayed on the Table of contents ...
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1answer
44 views

Comparing ASTER/SRTM dataset in ArcGIS Desktop?

Currently I am working with two data set ASTER and SRTM. I want to check their accuracy with reference to toposheet. How would I do that in ArcGIS Desktop 10.4? I want to check accuracy in terms of ...
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0answers
42 views

Elevation from GPS Vs. Query Elevation from Static TOPO database like SRTM

As far as I understand the GPS determines Elevation by real time calculations. What I don't understand is how? For example let's assume perfect (errors free) Lat/Lon fix by GPS. So I can query static ...
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0answers
214 views

REST API for global SRTM in .hgt format [closed]

I have been searching on internet for a quite a while and all the sites I found only gave on-site download option (like USGS EarthExplorer), no APIs. Is there any free or paid rest API for accessing 1 ...
3
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1answer
384 views

SRTM data represented in 3D using Unity. Problem texturing with sat images

I'm currently working on a project that represents geographic data in 3D using Unity. It basically loads, when given a GPS position, the area around it. For example, given the coordinate 50.5N 6.5E it ...
2
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1answer
316 views

Why there's a break between each .hgt srtm tile when importing to QGIS?

When I import the .hgt srtm elevation data to QGIS, the each tiles(each .hgt files) stitches with with a break or contrast variance or something like this: And it gets worst when rendering it with ...
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0answers
64 views

Discrepancies in SRTM 1ArcSec DEM

I have downloaded SRTM 1 ArcSec and processed it to retrieve topographic attributes. Prior to this, I have used 'fill' tool in ArcGIS as a pre processing step. Following is snapshot of clipped DEM; ...
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1answer
129 views

postgis SRTM3 different raster scale in same column

SRTM3 elevation data are stored in HGT files each containing 1201x1201 values. I want to store this information in a PostGIS raster column with a single band. To optimize my queries, I wanted to ...