Questions tagged [dem]

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

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20 views

What are the steps I go through to generate contour lines from one of the quickmap service layers e.g. OpneMapSurfer ASTER GDEM…? [on hold]

I want to generate contour lines for a relatively small remote area in Australia but my only source data is the free public data from the quickmap services options. What do I need to do to go from ...
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26 views

Using Viewshed Analysis in ArcGIS Desktop to Find Points Where Entire Area is Covered?

I have a DEM of an entire state and I would like to do a viewshed analysis. But instead of me using existing points to determine the viewshed, I would like to find all points where the entire state ...
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19 views

Join DEM and GPS data point ArcMap

I have a problem using ArcGIS. I have generate a DEM raster with a 3D online software and exported it in ArcGIS. So I have a raster of my surface. After that, I have some GPS point (x,y,z) that we ...
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30 views

Using Drone for Deliveries? [closed]

My company delivers medical supplies to health facilities in a some sections of an African country. This year we are expanding to cover over 2000 more health facilities. I've been brought on board to ...
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14 views

Getting started with ArcScene?

I have been using ArcGIS for some time and am playing around with arcscene for the first time. I am having trouble getting started. When I add a DEM to a blank project it renders as a uniform grey, ...
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2answers
45 views

Comparing several values within each cell of a DEM

I am working with a DEM and got a GPS line of my working area. I converted the GPS line into single measurement points. Now I want to compare each of these GPS points with the corresponding elevation ...
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13 views

Inverse values in raster heightmap

I have just converted a point vector into a tif using Rasterize in QGIS. And values are currently: How do I completely flip the values as it should be Min -98.95 and Max 2.3 I can't find much when ...
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28 views

Extracting Z coordinate from DEM - Python

I'm writing an algorithm in Python to extract Z coordinate of an DEM for a pair of X,Y coordinates. I'm using GDAL. The algorithm works correctly by extracting the Z coordinate from the DEM: Z = ...
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18 views

MicroDEM changes the aspect ratio of DEM

I downloaded a DEM from Open Topography (SRTM) and opened it in MicroDEM which changed the aspect ratio. The original DEM was 2329 px * 1679 px but that in MicroDEM when it was saved on disk was 2329 ...
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1answer
58 views

Finding lowest elevation in multiple polygons using DEM? [closed]

I have a polygon layer with six polygons. I need to have the lowest elevation point in each polygon using a DEM. The following explanation https://support.esri.com/en/technical-article/000011761 (...
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23 views

A GeoTIFF heightmap from SRTM embeds vertical planes along lat/lon grids in its 3D representation

I've downloaded an SRTM GeoTIFF from Open Topography and converted it into the grayscale image before I imported it into Blender to improve the quality. It is apparent that vertical planes are cutting ...
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1answer
12 views

How to Converting stream definition threshold to extract drainage network to metric scale?

I extracted two drainage networks from a DEM of 30 meters resolution with two stream definition thresholds: 1000 pixels and 500 pixels. Can you tell me what this thresholds represent in terms of ...
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21 views

SurfaceArea function of R giving very big unacceptable area for DEM?

I have been trying to calculate DEM area using surfaceArea function of R. It is giving a very high unacceptable erroneous area. I have a 10 m by 10 m USGS DEM file. I read the DEM using raster() ...
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1answer
31 views

QGIS - processing area and calculating volume of polygon with know elevation from a DEM

I got a DEM of a watershed and I need to create a dam at a fixed elevation (with a rectangular polygon corresponding at the top of the dam) and calculate it's area (including the slope (fixed value) ...
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2answers
33 views

Seeking Uruguay or South America DEM or DTM? [closed]

Is there any DEM (Digital Elevation Model) or DTM (Digital Terrain Model) for Uruguay or South America? I am aware of the Renare for Uruguay.
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1answer
24 views

Performing DTM compression using ArcPy?

I have a set of 32-bit TIFF files of DTM data (50 sm) and I need to save them as 16-bit. In order to save some space, I compressed them using LZW algorith and saved as 16 bit tiffs using Arcpy. But ...
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15 views

Finding the local extrema contour line on a DEM

I need to trace the top of a small levee on the side of a riverbank, based on a DEM. This line is similar to a contour line, except that it goes through the local maximum instead of a constant level....
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34 views

Creating DEM from contour pyQGIS? [duplicate]

How can I create Digital Elevation Model using python codes in QGIS software?
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2answers
39 views

Cannot read pixel value from DTM raster with QGIS

I am using this DTM: http://ags.cuzk.cz/arcgis2/services/dmr4g/ImageServer/WMSServer?request=GetCapabilities&service=WMS At ArcGIS I am able to ready pixel value of the raster but at QGIS it ...
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1answer
52 views

Generate a viewshed and merge it with another image using GRASS/GDAL command line? [closed]

I've found a tutorial showing exactly what I want to do (merge viewshed and hill shade or map) but unfortunately it is for QGIS users and I need it in pure command line instructions because I'm in a ...
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0answers
44 views

Generate an accurate DTM with photogrammetry?

I generated imagery from a low flying drone (40 M AGL) equipped with a mica sense RedEdge multi-spectral camera and have processed the imagery in PIX4D and now am attempting to do some analysis in ...
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24 views

How to remove bridges and dams from DEM

Is there anyway to alter elevation of DEM where there are bridges and dams for the flood routing of the River? I have to calculate discharge of the River from ancient times so at that time there ...
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19 views

Flow Distance Not Calculating for Entire Raster

I am trying to calculate the height above the nearest stream for an area. The problem is, it only does so for a portion ( the colored area below) of my area of interest. In the pic below, the black ...
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21 views

Elevation Map from Slope and Aspect Rasters

I am trying to create an elevation map (e.g., recreate a DEM) from the following input data: Slope Raster Aspect Raster ASCII file containing XYZ data points (Easting, Northing, and Elevation for ...
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1answer
35 views

Why is my DEM so bright for some tiles?

I downloaded an SRTM DEM GeoTIFF file from Earth Explorer. It looks fine when previewing it on Earth Explorer (see picture) but when added in ArcGIS Pro the DEM looks too bright in some of its tiles.
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1answer
25 views

Extrude building footprints using raster (DSM) values in ArcGIS Pro?

Is there a way to extrude a buildings footprint shapefile into 3D buildings using values from the area's DSM in ArcGIS Pro?
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2answers
52 views

Learning DEM resources? [closed]

I'm starting on a problem where I need to find the high point inside a polygon that exists inside the bounds of a DEM tile. I'm teaching myself GDAL and I'll be using Python to access the GDAL library....
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2answers
53 views

Creating contour file from DEM?

Using a 3-meter DEM, can I create an accurate 5 feet interval contour file? Or is the minimum interval contour I can get is 10 feet (roughly 3 meters)?
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1answer
56 views

CHM (Canopy height model) = DSM (Digital surface model) - DTM (Digital terrain model)

I want to create a canopy height model (CHM) which has the height of objects (trees, building, etc.) from DSM and DTM. Below is the step by step procedures which I did so far. I use open source s2p ...
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1answer
75 views

Creating 3D image from HGT files?

Is there any command line tool to create a 3D terrain from a DEM SRTM HGT file like this? I mean, given a camera position, a HGT file and a satelite image. EDIT 1 First try to adapt mdsumner's ...
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22 views

Editing DEM file

I'm currently working on a small town flood inundation mapping , the DEM file i am using for simulation contains a breakwater built after a recent flood event. My question is if it is possible to edit ...
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2answers
43 views

Lunar DEM elevation data scaled by 2

I am working with a DEM of the lunar south pole in QGIS. I have currently set the projection to "no projection", or Cartesian co-ordinates (origin at the pole). The horizontal locations of features ...
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19 views

No result with VRM tool ArcGIS

I am using ArcMap version 10.5. I downloaded the VRM tool from here: http://www.arcgis.com/home/item.html?id=9e4210b3ee7b413bbb1f98fb9c5b22d4. I followed the steps in 'read me; Unzip files (readme....
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2answers
70 views

Classify DEM pixels

I have a differential surface model dataset. That was made: DSM subtracted from DTM, so for example trees have negative height. It is a raster (TIFF) dataset, Type=Float32. I want to create a ...
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17 views

r.surf.area is underestimating area and giving negligible area

I am using r.surf.area in GRASS GIS to estimate surface area of a DEM. DEM is in EPSG4326 WGS84. It is giving a negligible area. Please give solution to this. Following is the output of r.surf.area.
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1answer
48 views

Error creating DEM with Nearest Neighbour tool in QGIS?

I have an issue when I am creating a DEM with the tool natural neighbour on QGIS. When I extract my data directly on Qgis I have no issue creating a DEM. My points are coming from different sources ...
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30 views

GRASS r.sun returns “ERROR: insol_time and incidout are incompatible options”

I'm trying to measure irradiance on a DEM using the r.sun tool in QGIS 3.6. I have grids for the elevation (EPSG:32735 - WGS 84 / UTM zone 35S), the slope and aspect (EPSG:4326 - WGS 84). I've tried ...
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1answer
70 views

r.surf.area command of GRASS GIS is giving a very small area

I am a beginner to GIS systems and am trying to calculate the surface area of a dem using r.surf.area command of GRASS GIS. The surface area it is giving me is unacceptable as it is very small. It is ...
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34 views

Assessing quality (accuracy and precision) of digital surface model (DSM)?

I have been trying to build digital surface model from stereo satellite images. I do some initial research of it, it looks like I have to go outside and manually measure the height of an object (...
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13 views

Calculating SCS curve numbers using DSM instead of DTM

Are the curve numbers (calculated by SCS Curve number method) through DSM (Digital Surface Model) valid? Most of the SCS curve number studies focus on calculating curve numbers through a DTM (Digital ...
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1answer
43 views

Downloading digital elevation model of United States?

I would like to download a digital elevation model of the United States, where can I do this? It doesn't need to be super detailed. But it would be nice, if was clipped at the country borders – ...
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2answers
69 views

Adding slope values to attribute table (QGIS 3)

I have a DEM raster and some points (one .shp for all points) plotted on it. I would like to know if there is a way to add the slope value of the pixel that each point is located in the attribute ...
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17 views

Losing raster quality when using raster calculator (ArcGIS Desktop 10.5.1)

I'm currently working with DEM rasters that I hillshaded. The data I received contain nodata borders, probably the footprint of the originial mosaic dataset. As I received them separately, I can't ...
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0answers
17 views

Stacking lidar-derived height raster as ancillary data for segmentation in ENVI?

I get a a black and white image after following these steps. Does anyone know why I'm not getting a color aerial image beneath the mask? My setup consists of these steps: I mosaicked several NAIP ...
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0answers
27 views

Basin Delineation using R

I am trying to get the polygon of a basin boundary using R. I got a 7.5 arcsec DEM that I download from this page: https://topotools.cr.usgs.gov/gmted_viewer/viewer.htm I look through a lot of ...
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2answers
167 views

Adjacent DEM color matching in QGIS?

I have four 15 arc second resolutions DEM files (15-C.tif, 15-D.tif, 15-I.tif, 15-J.tif) downloaded from viewfinderpanoramas.org. When I input them in QGIS I noticed that the 15-J.tif layer differs a ...
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35 views

Limiting sharp drop off of coastal DEM raster where there is no data using QGIS?

I'm stitching numerous tiled DEM's using Build Virtual Raster and then 'Align raster' function within QGIS 3.6 Original DEM has no data for sea area as expected: I get sharp drop off on coastal/...
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1answer
62 views

Converting DEM (TIFF) files to terrain files?

I want to create an app to show 3D using ol-cesium. In ol-cesium example it use cesium terrains, But I want to do it with my DEM files. How can I convert my DEM (TIFF) files to terrain files?
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1answer
32 views

Switching Mars DEM elevation values from negative to positive?

I'm using a DEM of Mars I got from UA's HiRISE website, and I want to convert it into an STL for 3D printing using the DEMto3D plugin. However, the raster values are all negative, so I thought I ...
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47 views

Extracting slope of aspect information using QGIS?

In What is SOA (slope of aspect)? @Spacedman explained to me what SOA means. Now I need help to understand how I could work with it and extract the data that I want. I want to use Qgis (with Grass ...