Questions tagged [dem]

For questions about Digital Elevation Models (DEM), Digital Terrain Models (DTM) and Digital Surface Models (DSM)

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Colour intersecting viewsheds by number of intersects

I'm creating a PyQGIS plugin which utilises the Grass7 r.viewshed algorithm. It creates viewsheds as .tif Layers in the project, using the main raster layer as a Digital Terrain/Elevation Model for ...
oliver's user avatar
  • 21
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18 views

Converting vertical datum of Lowest Astronomical Tide (LAT) to EGM96

I want to model the impact of sea level rise (SLR) on the coast zone of an Asian country using a modified bathtub model. The SLR projections include AR6 results and extreme sea level (ESL) by high ...
Yuxuan Ye's user avatar
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1 answer
34 views

Outlier's neighbours of a raster analysis in Python/GIS

Starting with point clouds from various drone flights, I created a 0'1x0'1m cell raster with the DEM of Differences (DoD). Next, in order to clean outliers cells, I calculated the 0'1 and 99'9 ...
Deskrub's user avatar
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1 answer
108 views

GRASS r.horizon returns nonsense

I am trying to calculate the horizon profile from a point on a mountainside, through the appropriate DTM elevation file and the GRASS function r.horizon.height (via QGIS). However, the output looks ...
elevation_modeller's user avatar
1 vote
1 answer
41 views

QGIS DEM (Raster) merge: errors

I'm trying to merge 4 tiles (ASC) of a French 1m digital elevation model. Files are loaded in QGIS, they bear no errors, value range is coherent. Merging comes with errors and the result is a raster ...
Gilles's user avatar
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Python: Flood a DEM with a specific amount of water starting from a seed point [closed]

I want to calculate the flooding area produced by a specific volume of water starting from a seed point. Needs to be simple (the real process can be super complex as explained here) and fast. For the ...
stray_dog's user avatar
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20 views

Generating orthomosaic from DEM in Metashape

I'm using Metashape to make a point cloud from georeferenced drone images using the basic workflow (Align photos -> Build Point Cloud). I then export that and align it to a LiDAR cloud we have from ...
waiiana's user avatar
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35 views

Identifying / digitising small surface features automatically in QGIS

I need to locate small features on a digital surface model (dsm) in qgis and get their coordinates. I have a field surface with distributed molehills they show up in the dsm but is there a tool that ...
user878557's user avatar
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1 answer
25 views

Generate 3D rendering / DEM from NOAA ENC files?

Is there a way to generate a 3D rendering of the underwater topography lines from NOAA ENC files in QGIS? I want to take the depth contours and generate a 3D or shaded relief map from this. I ...
Jeremy's user avatar
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Using DEFRA LiDAR dtm-1m to calculate slopes etc in QGIS

I have a shapefile of woodland polygons and want to calulate slope and slope orientation of the polygons. I am using the LiDAR Composite Digital Terrain Model (DTM) - 1m in QGIS. Available at: https://...
user197410's user avatar
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QGIS Slope: Slope processing tools not working as expected using DEM

I have a NRCS 2M DEM Bare Earth file for which I have already successfully applied the Hillshade and Aspect tools in my QGIS v3.34.1 project (see below). Now I am attempting to determine slope using ...
Linus's user avatar
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Using a DEM to elevation data to an existing point shapefile

I have a point layer called air_quality_locations which contain points with air quality and ozone readings across California. I also have a 30m DEM for California. How do I take the elevation data ...
Jonathan Sharp's user avatar
4 votes
1 answer
200 views

Filter for south pointing areas from a DEM

I want to get all south pointing areas within a city. These will be the ideal locations for PV-Plants. I am aware that a DEM is rasterdata and there is not an attribut table like for shape files/...
BAE_23's user avatar
  • 601
1 vote
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23 views

QGIS 3D viewer autoupdate frames from temporal controller

I am using QGIS 3.30.3 and I am trying to make a cinematic with the 3D viewer of some flood tiles. I have a Digital elevation Model and a few flood tiles with temporal information. Using the temporal ...
luis castillo's user avatar
2 votes
0 answers
51 views

DSM to DTM limited by polygon

I am currently struggling with a specific DSM to DTM conversion requirement over a raster dataset in QGIS. DSM was born from photogrammetry and I need to automatically get rid of houses and vegetation....
ďobo's user avatar
  • 121
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Export DEM file of specific places and import into VBS3

I want to get a DEM file to load into VBS3. I followed the instruction from the internet that use Google Earth Pro. Here is the link: The instruction that I followed But the DEM file I've gotten from ...
nghia_pham's user avatar
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Issues Opening Large DTM File in QGIS - ‘Bad Allocation’, 'Error occurred while parsing element at line 1 column 1' Error

I’m trying to open a large DTM file in QGIS but I’m encountering errors. The data is a DTM 5x5 m map of the Lombardia region. The .ige file is 7.7 GB and the .img file is only 522 KB. I’ve tried ...
Zea Mays's user avatar
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49 views

A 5-feet DEM - what does it mean?

When it says that a particular DEM is say "5-feet DEM" - does it mean that: The distance between two points when elevation was actually measured (or source data before interpolation) is at ...
user1889930's user avatar
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23 views

Similar boundary but different spatial resolution

I am not sure if I can express it properly considering the lingo but, I am trying to create maps that show comparison of different spatial resolution in determining soil loss in a given watershed. I ...
Suzhii's user avatar
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DEM from LiDAR using cloud compare

I am working on overseeing a comprehensive flood analysis project in Bardonecchia, Turin, Italy, post the August 2023 flood event. I have been handed over the LiDAR file .las in which flood occurs. I ...
Ameer Turab's user avatar
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Delimit a watershed associated with a polygon - ArcGIS Pro

I have nearly the same question as Calculating watershed associated with polygon using DEM and QGIS but for ArcGIS Pro. I am starting with a polygon representing property boundaries and I need to ...
Erin's user avatar
  • 157
1 vote
2 answers
73 views

How to export an IDW DTM as a GeoTIFF file in R

I have loaded both raster and lidR packages within RStudio and I am trying to export the IDW DTM files but have been receiving errors about 'format'. I have exported a TIN DTM already however with IDW ...
Niall Gavin's user avatar
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31 views

(QGIS) How to improve Hillshade view of SRTM

I've downloaded some DEMs using opentopography plug in. When I change the render type to hillshade and try to zoom in to actually be able to view anything I just get black lines with a grey background....
Sylvino's user avatar
  • 105
2 votes
1 answer
111 views

Aligning two orthophotos with Metashape

I am working in Metashape Version 2.0.З. I have very basic skills. I have two terrain survey results taken by an unknown UAV (the same UAV was used) in different years without reference points on the ...
Comrade Che's user avatar
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2 votes
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53 views

Strange parallel lines in the middle of the basin

I prepared a stream network for my study area using ArcGIS. Why am I seeing those strange lines in the middle of the map. I used 3 Second SRTM Derived Digital Elevation Model (DEM) from https://ecat....
Anju's user avatar
  • 21
1 vote
0 answers
32 views

Exporting Multilayered DEM Maps from ArcGIS Pro

I'm currently working on a project in ArcGIS Pro where I've created a map featuring multilayered Digital Elevation Models (DEMs) with various blend modes applied. My goal is to export this map for ...
blankaal's user avatar
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0 answers
87 views

Some problems with gdal_translate to translate from GeoTIFF to 32 bit grayscale TIFF, exr or similar [duplicate]

I need 32 bit grayscale DEM map from GeoTIFF to crop it in Photoshop and use in 3D applications as height displacement map. I use Windows and have images copied in OSGeo4W Bin folder so there is no ...
Alex J.'s user avatar
  • 119
2 votes
1 answer
267 views

QGIS smooth mapzen DEM to create a very simplified topographic map

I am using Mapzen global terrain to create a topographic map. How can I get a very simplified result like on the map of Greece? Should I use contours lines ? And how to smooth them ? (wich algorithm ...
Wilcar's user avatar
  • 841
1 vote
1 answer
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How to fill pits for a DEM/CHM when using the LAScatalog engine?

I'm trying to create a DEM/CHM using the LAScatalog engine. I've followed the steps in the lidRbook. In chapter 6 section 6.4 the post processing fills in areas no missing values for single las files ...
Walshe_d's user avatar
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When loading a DEM in Google Earth Engine, it doesn't load the full map extend

I want to download a digital elevation model for a major part of Europe. Last time I tried it with the "NASA NASADEM Digital Elevation 30m", wich can be found here: https://developers.google....
Mark's user avatar
  • 29
2 votes
0 answers
46 views

Getting distance between DEM's zero elevation and earth's center [closed]

I'm using the DHM25 DEM available here: https://www.swisstopo.admin.ch/en/geodata/height/dhm25.html EPSG:21781+5728 (Swiss CH1903 / LV03 + LN02 height) I need to use the earth's radius under ...
fariadantes's user avatar
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0 answers
36 views

Create a buffer on a single LAS file using lidR

I want to create a buffer for a single LAS file in order to test different algorithims for DTM creation on a small scale before scaling up to all my files using LAScatalog. I know LAScatalog creates a ...
Walshe_d's user avatar
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0 answers
63 views

TIN interpolation keeps discarding original values of sample and interpolates them [closed]

I'm trying to make a DEM in QGIS using TIN. I have a set of points with elevation data on one of the attributes. My problem is that when I generate the raster, the initial set of point values are lost ...
A rookie's user avatar
3 votes
1 answer
108 views

Separation of DSM as Building DSM and Canopy Height Model in QGIS

I am currently trying to separate the DSM as Building DSM and Canopy Height Model. I also have DTM, Building Footprint data. Digital Surface Model Building Footprints. For separation I converted the ...
sevvaldurmazbilek's user avatar
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0 answers
60 views

3D modelling with DEMs and ThreeJS

I am trying and right now in the search of methods to visualize 3D terrain with the use of the JS framework "ThreeJS" and so far I have only got through to visualizing with the QGIS2threeJS ...
DilankaMunasinghe's user avatar
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0 answers
28 views

USFS Fusion software bare-ground DTM input

I downloaded 1-m 3DEP dem from USGS to use as input for Fusion bare-earth DTM (description here) and I'm using USGS lidar data for the point cloud to make a Canopy Height Model. Due to data size ...
Jonathan Burton's user avatar
1 vote
0 answers
183 views

How to correctly convert a DEM/GeoTIFF to 3D Contours in a DXF file

I am trying my darndest to turn a DEM/GeoTIFF into a 3D DXF file of contours but so far haven't been able to make it work correctly - I still end up with a seemingly 2D DXF that I can open in ...
Lost Mapper's user avatar
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Calculating MESO-scale slopes from a DEM

I have a coastal DEM which I want to use to calculate the cross-shore slope with ArcGIS Pro. In the image below I've plotted the zer and five meter contours, and what I want is to calculate the ...
anner.paldor's user avatar
0 votes
1 answer
177 views

Enabling render type for Mapzen Global Terrain in QGIS

I'm trying to change the color ramp on a Mapzen Global Terrain layer and only 'Singleband color data' is available in render type. 'Singleband pseudocolor' is not available. This is occurring in QGIS ...
Andy's user avatar
  • 3
0 votes
1 answer
42 views

Plotting real (normalized) las values on dtm

I am trying to plot a las where I filtered objects, that have a first and a last return simultaneously (objects in the las file), onto a created dtm of the same las. I am able to produce a good result....
utz's user avatar
  • 3
0 votes
0 answers
142 views

How to interpret values of elevation standard deviation statistic (and not elevation mean) from DEM

I am trying to interpret the standard deviation of elevation to understand the topographic landform of my study area. We have 2km*2km grids in the study area for which we extracted certain landscape ...
RashmiSRana's user avatar
0 votes
0 answers
24 views

Generate and populate a grid from points in a geopandas dataframe [duplicate]

Context: I have a geopandas dataframe, with two columns 'geometry': full of shapely.geometry.point.Point. 'h_mean': gathering the height of a surface at those points I want to create a 2D spatial ...
Nihilum's user avatar
  • 143
0 votes
0 answers
17 views

What does the Fetch Analysis variable in Whitebox Tools represent?

I have a DEM of Scotland. I used BreachDepressionsLeastCost to process it. I then derived the Fetch Analysis raster. The problem is that the values, both positive and negative, are very high. The ...
Michael Dalvean's user avatar
3 votes
1 answer
105 views

Reading GeoTIFF from path and converting it into PostGIS raster data type

I need to read the raster file (DEM) from path directory and turn it into PostGIS raster data type. I formed this SQL query: SELECT ST_FromGDALRaster(pg_read_binary_file('D:\dems\img.tif')) FROM ...
Anna's user avatar
  • 43
0 votes
0 answers
57 views

How to derive first return points from a raw LAS data file

I have a raw (never classified) las dataset derived from UAV that I am attempting to obtain a DEM, DSM, and eventually CHM from. I have successfully been able to classify ground points and vegetation ...
greg684's user avatar
2 votes
1 answer
237 views

Blurry resolution when uploading DEM 5ft data onto QGIS

I am creating a map for the nature preserve I work at. I have been downloading Kentucky elevation data from THIS website. You can see that there is a really high resolution, and I am able to see the ...
Madeline Cox's user avatar
3 votes
2 answers
273 views

Creating topographic "layer cake" map a.k.a. Tanaka contour in QGIS

I'm wondering if there is any way to create a map similar to the image below. Basically, it would be the contours extruded, add a singleband pseudocolor ramp as the color on top, and be able to ...
Jon Altschuld's user avatar
0 votes
0 answers
28 views

How to have a good rendering with mdenoise - DTM LiDAR denoising

I'm trying to generate a clean slope map from a LiDAR DTM. Due to LiDAR high resolution, the slope map is full of noise. So to do this, I use mdenoise library. It works quite well but it generates ...
Tim's user avatar
  • 83
0 votes
1 answer
54 views

Check if Layer is a DEM programatically

I loaded several layers, some of them are DEMs of different data type: ASCII and TIFF. I want to check every layer if it is a DEM or not. I found the function hasElevation, which should return true if ...
Lukschn's user avatar
  • 115
1 vote
1 answer
133 views

Reprojecting raster in QGIS moves all values to completely different range

This question has been asked here multiple times. And every time, it seems that the people offering answers don't understand the magnitude of what's happening. When I reproject a DEM raster with this ...
Tom Haws's user avatar
  • 157

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