Questions tagged [terrain]

The vertical and horizontal dimension of land surface

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Terrain Ruggedness index to polygon

I need to calculate ruggedness for a circular region extending x meters away from a central point. The TRI function in Terrain uses Wilson (2007) equation to calculate TRI for an entire raster TRI <...
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What is the difference between TIN vs MESH vs TERRAIN in the context of GIS?

I couldn't seem to fully understand the differences between TIN, MESH, and TERRAIN dataset formats in GIS. Per Wikipedia a triangulated irregular network (TIN)1 is a representation of a continuous ...
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How to determine the area size of a terrain for which I want to calculate its roughness

I want to calculate the wind speed on the ground for a specific location. In order to do so I will use the log wind profile. One of the input variables of this formula is the surface/terrain roughness....
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Terrain creation error using a GeoTIFF file with HEC-RAS 6.2 - "object reference not set to instance of object"

I am attempting to import a TIFF file created in QGIS, into HEC-RAS. I have a projection file as the SRS definition for HEC-RAS, which is derived from a shapefile that lines up with the spatial extent ...
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Band used for deformation estimation using In-SAR

Which polarization of SAR data (C-band - Sentinel-1A) shall I use to get a better deformation map of a mountain terrain - VV or HH?
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Calculate slope along line feature for line segments of equal elevation?

I would like to calculate the surface slope of a glacier in the Swiss alps. In ArcGIS Pro this can be done using the Add Surface Information Tool. The output is a data table with the slope for each ...
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Terrain correction TerraSAR-X images

I am trying to perform terrain correction on a SAR image using GDAL. I tried using simple gdalwarp, but the accuracy is not enough for me, so I decided to use: gdalwarp -multi -wo NUM_THREADS=ALL_CPUS ...
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Error calculating aspect from DEM in R using raster/terra

I have a DEM file gathered using R. The raster and terra packages both have a function to calculate aspect, called terrain(). When using the terrain() function and the units="degrees" ...
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2 answers
136 views

Converting aspect/direction raster from geographic degrees to arithmetic radians

I have a raster/grid representing e.g. terrain aspect or flow direction, coded in geographic degrees (0-360°, clockwise from the north). I would like to convert it in arithmetic radians (0-2π, ...
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Creating TIFF from Contour Lines

I need to quickly create a TIFF terrain (shades of grey terrain) from contour lines, or rather to create a GeoTIFF. In the past, I extracted vertexes from the contour lines and used that to create new ...
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Generate GLTF/OBJ models from quantized mesh (terrain) in CesiumJS?

I’m exploring ways to generate gltf / obj models from terrain mesh. My goal is to show 3d cut-fill volume calculation, something like the following - I realized that I don’t need to DEM to generate ...
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How to query height of a given lat long coordinate from server side?

I need to some calculation with terrain surface, I use cesium but it works slow. Cesium has a method sampleTerrainMostDetailed, it gives me height of given coordinates but it calculates height on ...
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2 answers
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Creating Contour Lines in QGIS 3.16 with a distance of 0,10 m

I would like to create Isohypses (Shape) ("Create contour lines") with a distance of 0,10m in a Digital Terrain Model (Shape File). While processing the command, there are some errors poping ...
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Exporting terrain shape vectors

I'm trying to export from QGIS a physical map, with terrain info (shades from green to brown so to speak). I managed through Contour tool to have the single lines altitude map and export to SVG, but I'...
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Plan curvature in QGIS

I am trying to obtain plan curvature from a DEM. So far I have tried two methods from SAGA and GrassGIS plugins, however both do not seem to work and give errors. Do you have a workaround suggestion? ...
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300 views

Using Watershed Basin from SAGA in QGIS

I have a weird phenomenon going on in QGIS. I want to derive a channel network and also the catchment areas using "watershed basin" from SAGA. In the end I want to have the flow direction ...
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1 answer
101 views

How to interpret Terrain Ruggedness Index according to Wilson et al. (2007)?

Is there a categorical scale used to interpret values from the Terrain Ruggedness Index as calculated by Wilson et al. (2007), which is used in the raster library in R?
2 votes
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117 views

Interpreting Ruggedness Index calculated from SRTM Tiles

I am looking for help interpreting the values from Ruggedness Index calculations. I downloaded SRTM tiles using the SRTM Downloader plugin in QGIS. Then I calculated ruggedness from SRTM tiles in QGIS ...
2 votes
1 answer
277 views

Intersection of an arbitrarily oriented 3D plane with a terrain DEM

In a nutshell I'd like to compute the intersection of a 3D plane (defined by 3 points) and a terrain (given as a raster DEM GeoTIFF), and more particularly the part between two lines of that plane. ...
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300 views

Calculating direct solar radiation using QGIS and GRASS

I am using QGIS 3.16.8 and GRASS 7.8.5. I would like to compare two places in my study area climatically. Since both are only a few 100 metres away, I assume that they only differed in terms of slope ...
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1 answer
115 views

Reproducing terrain ruggedness index from the original paper example [closed]

I am not able to reproduce the terrain ruggedness index for the example used in the original Riley et. al paper. The example is as follows: When I try to reproduce the numbers in MS Excel I get ...
2 votes
1 answer
116 views

How to calculate the terrain profile in Profile Tools plugin

Now, I'm trying to calculate terrain slope(°) using pyqgis using below process. Along the specific lines which I want to know the terrain profile, I generated the points using 'qgis:pointsalonglines'....
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An error occurred when using the terrain function in the production of Shiny dashboard

I am new to the 'shiny' package. I just try to produce an aspect map from the existing DEM data using the Shiny dashboard for training purposes. However, I faced the below warning in R and error in ...
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Grid from SAGA natural neighbor results in black grid

I'm new in QGIS and I'm following tutorials mainly on YouTube so I created a path in Google Earth then exported to kml which is converted to txt via GPS visualizer. When added delimited layer it shows ...
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285 views

Why do I get negative values for the topographic position index (TPI)?

I run into issues, when trying to calculate the topographic position index (TPI). I get values ranging from -13 to 17. And the resulting layer looks a bit odd, too: If I understand it correctly, this ...
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Free or FOSS Elevation API for Heightmaps (image files) instead of elevation points

I'm coming from a Blender background, in which simple FOSS extensions exist (like BlenderGIS) that download SRTM/Aster Elevation Data and make a terrain based on this. I'd like to make something ...
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1 answer
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How to get elevation raster data at custom scales for a specific region?

I'm new to GIS and trying to obtain elevation data for a specific region, transformed to raster data with a custom cell size of 10 meters. My first attempt was to download a TBDEM dataset from USGS ...
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130 views

How do I overlay vector data over a 3D terrain basemap?

I would like to create a map that is similar to the one found here: https://www.reddit.com/r/MapPorn/comments/lpo557/geological_map_of_north_america/ . I'm thinking that you could replicate this with ...
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r.slope.aspect grass gis datum format on dx and dy analysis

I'm performing terrain analysis due to photovoltaic installation on QGIS with r.slope.aspect plugin. I'm interested in evaluate differently N-S slope and E-W slope based on the PV system I would ...
1 vote
1 answer
550 views

Terrain Ruggedness Index (TRI) calculated in QGIS is approx 4 times that calculated in GDAL

When I calculate TRI using QGIS and GDAL tools for the same elevation DEM, I get results that are comparable between the two except that the absolute values in QGIS are approximately 4x that in GDAL. ...
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1 answer
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Selecting Terrain Dataset by elevation in ArcGIS Pro

I have added the Terrain Dataset to my project in ArcGIS Pro. I would like to select the areas which have an elevation above some threshold. Eventually, I want to use this selection as a clipping mask ...
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NA values as result from Grass functions (r.slope.aspect, r.sim.water) in R

As the result from r.slope.aspect I get a raster with only NA values. r.param.scale works, but doesnt generate dx and dy maps, which I both need for r.sim.water function. Code snippet 1 (initialize ...
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203 views

Using Aspect tool in QGIS

For my bachelor thesis in biology I´m working with QGIS 3.14 (Pi) and tried to create a layer where the slope aspect/expositon/exposure is presented. I´ve got a DTM1 on hands. There is this function ...
2 votes
3 answers
156 views

Terrain aspect similarity

I have a point data set with terrain aspect at the location of the points, measured in degrees. I want to compute the similarity of aspect between the points, e.g. 70° is similar to 90°. This is ...
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Lidar Dataset for Toe and Crest Detection

I have read a paper on Terrain Toe and Crest Feature Detection and Labelling forAutonomous Mining and started working on building the code for this. But I am unable to find the dataset used in the ...
2 votes
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244 views

Extract terrain coordinates as seen from a viewpoint + FoV in a digital globe

Context Every one working with photogrammetry or 3D knows what a depth image is. For example OpenCV defines a "depth map" from a stereo pair, e.g.: where the darker a pixel is, the greater ...
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How do you export a 3d-model in QGIS to a file that can be read in Rhino?

I am really new to QGIS and haven't really gotten familiar with all the functions yet. I've made a 3D map/model in QGIS, and would like to export this in a file format so that I can use it as a ...
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2 answers
635 views

Earth engine - ee.Terrain.slope() output at wrong resolution after DEM mosaicking

The big picture: I'm using Google Earth Engine (Javascript) to do a terrain correction on Sentinel-1 imagery, as in Andreas Vollrath's work. However, I want to use a higher-resolution Canadian digital ...
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2 votes
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Using ArcMap to build a Terrain DEM that looks exactly the same as a TIN built from the same point shapefile

I am attempting to replicate DEMs previously constructed as TINs in the Terrain format. Building a Terrain and a TIN out of the same point shapefile produces two maps that look extremely similar, but ...
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2 votes
1 answer
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Getting from a USGS historical topographic map to a Unity terrain heightmap

Is it possible to start from a USGS historical topographic map and get to a Unity terrain heightmap? To see an example of the kind of historical topo map I am talking about: Go to: https://ngmdb....
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Define Terrain/Elevation textfile data format

I have a program that can visualize terrain/elevation data but will only recognize files in the below format. It has the extension .map but it is not recognized by QGIS or GDAL so I believe it may be ...
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How do I "flood" a terrain in Cesium to represent a high water level

I am thinking about using a plane object to represent a water level by rendering it as a certain height above ground using Cesium. Is there any example code that
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3 votes
1 answer
522 views

Creating contour lines from DTM in PostGIS

Is there any possibility to compute contour lines from a raster DTM directly in PostGIS on a PostgreSQL database? I have only found this solution based on points "Fast contour lines using plain ...
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1 answer
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What is meaning of scale on x and y axis of image using matplotlib

I am finding elevation of a region using richdem. Can somebody tell me what is the meaning of the scale which is on the x and y axis of the image? import os import numpy as np import matplotlib ...
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201 views

DSM results from WebODM are not correct [closed]

I am new to WebODM and I am trying to generate DSM and Orthomosaic images using default settings in WebODM. The Orthomosaic image is correct by providing GCP but the DSM file is having inaccurate ...
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1 answer
916 views

Digital elevation model - getting files in the .DEM extension

Could you tell me from where can I get the Digital Elevation Model data in the .DEM file extension? The option for QGIS here: https://www.qgistutorials.com/en/docs/working_with_terrain.html shows the ...
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1 answer
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How accurate are Ordnance Survey MasterMap topography spot heights?

The spot heights in the Ordnance Survey MasterMap sample data over Exeter with feature code 15404 are presented as an integer value in metres. But how accurate are these spot heights? I had assumed ...
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Problem with weird values in DTM and not showing correct elevation

I am still new to Gis and don't know if I understand what is wrong. I am working in a ocean survey program with point clouds. As seen on the picture the minimum depth is 1,92 and maximum 12,02. I ...
1 vote
0 answers
464 views

Point/Area location of data in reference to geotransform of raster

I'm trying to understand how to interpret the position of pixel data within a GDAL raster, specifically as it applies to files containing height data. I'm create Triangular Regular Network (TRN) for ...
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ArcGIS 10.X - DEM raster creation - Point to Raster vs. Terrain to Raster tools [closed]

I have a bunch of LiDAR data that I need to make a raster DEM & DSM from. From what I can gather my options are use the Point to Raster tool directly on the Multipoint feature or make a terrain ...
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