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24 votes

Splitting raster into smaller chunks using GDAL?

There's a bundled python script specifically for retiling rasters, gdal_retile: gdal_retile.py [-v] [-co NAME=VALUE]* [-of out_format] [-ps pixelWidth pixelHeight] [-overlap ...
mikewatt's user avatar
  • 5,093
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
20 votes
Accepted

Hillshade results look too grainy

I think you are using Geographic CRS not Projected CRS. Usually this hillshade output is due to you are not using a projected DEM such as UTM projection with a meter unit. You need first to reproject ...
ahmadhanb's user avatar
  • 40.9k
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
18 votes
Accepted

calling gdal_merge into python script

Add an empty argument in the first approach (because gdal_merge.py parses arguments starting from 1 and not 0): import sys sys.path.append('C:\\OSGeo4W64\\bin') import gdal_merge as gm gm.main(['', '-...
Antonio Falciano's user avatar
17 votes

Viewing LIDAR data (.las) in QGIS?

QGIS 3.18+ supports point cloud visualisation natively.
Peter Petrik's user avatar
  • 1,455
13 votes

How to perform a slope analysis in QGIS?

Slope analysis is performed on a DEM (raster layer with elevation values). This is one way to do it. If your contours have an elevation value, you can use the interpolation option (raster/...
Gerardo Jimenez's user avatar
13 votes

Hillshade shows grid texture artifacts

The problem is because the DTM has a high-resolution pixel size when data (in my opinion) doesn't have the same resolution is some areas. For example, direct hillshade raster: Check pixel values (...
aldo_tapia's user avatar
  • 13.7k
12 votes
Accepted

Querying Elevation Data in Postgis

Your elevation points are definitely regularly aligned and hence there is no need to bother about nearest neighbors. The value of the pixel in which your point fall into is always the value of the ...
Pierre Racine's user avatar
12 votes
Accepted

Making an animation of an evolving digital elevation model

Probably the best tool for this is Paraview. Once you've downloaded and acquired that you'll want to load your images: Use the CSV reader to load them: Below, you can find filters faster by pressing ...
Richard's user avatar
  • 1,831
12 votes
Accepted

Update DEM based on line feature in QGIS

You can use r.carve within QGIS and set up a negative stream depth to increase the height of your DEM along your line feature (In the image below a positive stream depth have been applied to the DTM)
wanderzen's user avatar
  • 2,140
11 votes

Seeking tool to generate Mesh from DTM?

We have just created an open source project that will help you do exactly what you want. Tin-Terrain is a simple command line tool that will generate a mesh from DEM files either as TIN or TRN. The ...
morishuz's user avatar
  • 265
11 votes

In hydrologic terrain analysis is there a difference between "pits", "depressions", and "sinks"?

There is a difference, and I recommend the typology presented by Lindsay (2015) be used. Lindsay (2015) presents a typology which defines a pit as a single cell in a DEM whose elevation is below that ...
Richard's user avatar
  • 1,831
11 votes

How to replace pixel values in a single band DEM?

You can do something similar using gdal_calc.py, e.g.: gdal_calc.py -A dtm.tif --calc='((A>=100)*(A<=200))*A+((A<100)*0)+((A>200)*0)' --outfile=dtm_reclass.tif --NoDataValue=-32767 This ...
dmci's user avatar
  • 4,892
11 votes
Accepted

Generating STL (3D) file from raster ASTER GDEM data?

I know QGIS has a plugin that export DEM to STL using DEMto3D, and I tested on a DEM and it worked. The description of the plugin mentioned that clearly: DEMto3D is the first tool that links GIS (...
ahmadhanb's user avatar
  • 40.9k
11 votes
Accepted

Merging drone/photogrammetry-derived DEM and satellite-derived DEM using ArcGIS Pro

Assuming: both are in the same projection / coordinate reference system, you have a Image/Spatial Analyst license, and NoData has been set correctly on the High res DEM. You could use a Raster ...
user2856's user avatar
  • 66.5k
11 votes
Accepted

Filter for south pointing areas from a DEM

You can calculate Aspect to get a raster with values ranging from 0-360º, then reclassify south facing values to 1, and the rest to 0/Nodata. I use 150-210 as the definition of south: First part of ...
BERA's user avatar
  • 73.8k
10 votes

Extracting Values to Points without ArcGIS Spatial Analyst?

Script: import arcpy, traceback, sys, os pntFile=arcpy.GetParameterAsText(0) rasters=arcpy.GetParameterAsText(1) rasters=rasters.split(';') theFields=[x.name.lower() for x in arcpy.ListFields(...
FelixIP's user avatar
  • 23k
10 votes

Different DEM range values in QGIS and ArcGIS

In both software, the initial data range is just an estimate, which can easily be manipulated. For instance, should you display several DEM side by side, you will likely want to use a common range so ...
JGH's user avatar
  • 42.1k
10 votes
Accepted

Adjacent DEM color matching in QGIS?

In the main menu bar, go to Raster | Miscellaneous | Build Virtual Raster and select all the tiles you want to group (don't forget to uncheck the Place each input file into a separate band tickbox). ...
Gabriel's user avatar
  • 3,145
10 votes
Accepted

Sampling points in raster without generating new file in QGIS

You can use the raster_value function in an expression in the Field Calculator to update a field in your point layer with the pixel value from an underlying raster: raster_value( 'DEM', 1, $geometry )...
Ben W's user avatar
  • 21.7k
10 votes
Accepted

Elevation from TIFF file

Save the Excel file as CSV In GIS, add the CSV file to QGIS using "Layer > Add Layer > Add Delimited Text Layer" Use "Sample raster values" from "Processing Toolbox (...
Kadir Şahbaz's user avatar
10 votes

Extract raster value at each vertex from line, while keeping the line

You can use "Drape (set Z value from raster)" tool to set the z value of every vertex in the densified line to a value sampled from a raster.
Kadir Şahbaz's user avatar
10 votes

Make the pixel values of the DEM correspond to the actual heights

I had a similar SE-GIS question several years ago. The answer: by default, QGIS displays an estimate of the min/max values, which results in the unexpected values. To see this, open up the Min/Max ...
Stu Smith's user avatar
  • 8,290
10 votes
Accepted

Blurry resolution when uploading DEM 5ft data onto QGIS

You have downloaded a digital elevation model (DEM). The top screenshot is showing a hillshade. You can either style the DEM as a hillshade or create a hillshade. Style F7: The same layer with ...
BERA's user avatar
  • 73.8k
9 votes
Accepted

Extract river polygons from DEM

One approach that our amazing intern recently used, which turned out really well for us: Fill the DEM Calculate flow direction on the filled raster Accumulate the flow of the flow direction output Do ...
Tom's user avatar
  • 4,128
9 votes

Generating series of cross sections (profiles) along line using QGIS?

I've been trying to find how to do this for a while. @Kazuhito's comment led me to find this. You need two things:- a line (your axis or route) a DEM (raster) Convert Points to Line You can get ...
Steven Kay's user avatar
  • 20.4k
9 votes
Accepted

Merging hillshade / DEM data into color relief single geotiff with QGIS and GDAL

gdal_calc.py is a good tool to perform mathematical operations and functions on raster images. The gamma and overlay functions are fairly simple to write and you can string together some temporary ...
Logan Byers's user avatar
  • 2,859
9 votes

Delete raster values lower than 0

Use raster calculator to set all values under 2 to 0: ("DEM@1">=2)*"DEM@1" "DEM@1" represents the name of your layer (difference layer). The output of "DEM@1">=2 will be a layer with 0 and 1 ...
aldo_tapia's user avatar
  • 13.7k
9 votes
Accepted

Finding pixels in DEM with 5% slope or less?

You mention 3D Analyst so I am assuming you have ArcGIS. Use the tool ArcToolbox-3D Analyst Tools-Raster Surface-Slope to create a slope surface from your LiDAR data. Use the tool ArcToolbox-3D ...
GBG's user avatar
  • 9,930

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