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

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20 views

generating DEM from many files with .asc extension for each cell

I am the beginner of arcswat and have a problem in the first step of setup. I have recieved a folder of DEM which is contain many files with .asc extension each representing one cell when I add them ...
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0answers
36 views

SRTM data to 7.5 min DEM or 1-deg DEM

I have an issue. I have SRTM data from here (http://www.webgis.com/srtm3.html) which is approximately 90 m / 3 arc-second. I want to convert it to 7.5' DEM or 1-deg DEM. Is it possible? Or is there ...
4
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3answers
186 views

What is the difference between DEM data sources?

I have started experimenting creating basic 3D elevation models in QGIS recently. It turned out for me that there are several free sources of DEMs, like USGS's EarthExplorer, CGIAR-CSI's Digital ...
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0answers
23 views

Zonal smoothing on a specified area of a raster?

Is there any way to smooth a specify an area on a raster, such as a DEM, and smooth it? For example, I'd like to smooth out the artifact highlighted in the red box. What is the best course of ...
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2answers
59 views

How to get the z values from a DEM?

I have to get to know the approximate amount of volume of rocks in one area. For that, I need the elevation information to see where slopes or inclinations are located. I downloaded from the USGS ...
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1answer
73 views

Reading 1/3 arcsecond DEM data using C++?

I am writing my own application to use and present elevation data. So far, I've been easily using the three arc second SRTM data presented in ArcInfo ASCII format. But now I'm looking to use the ...
2
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0answers
26 views

Does USGS 3DEP data use a hash or checksum?

I'm downloading some USGS 3DEP elevation data, e.g., the file at the following URL: https://www.sciencebase.gov/catalog/item/563afea8e4b0d6133fe7357b The "ID" of this file is given in both the URL ...
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0answers
25 views

Ideal minimal area for watershed automatic delineation using DEM SRTM

I need to do a bunch of analysis on a city using for that, watersheds . As smaller the watersheds are, better are quality of my work. Due to the vertical accuracy of SRTM DEM, I know there are some ...
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1answer
42 views

How to edit a DEM in ArcMap

I want to take a DEM and edit it using a tool in ArcMap where it will take all the areas above a certain elevation and lower them all to the elevation I choose. For example, I would want everything ...
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0answers
69 views

Creating a Greyscale DEM from Multiband (RGB) GeoTIFF in QGIS

I'm trying to merge some river bathymetry with LiDAR from the surrounding riverbed using QGIS 2.14.0 Essen. The river bathymetric data is a GeoTIFF, and it comes with a separate scale associating the ...
2
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1answer
30 views

How do I know topo layer contains DEM-altitude? ArcMap 10.3

How do I know if a topographic layer contains DEM-altitude? ArcMap 10.3
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1answer
75 views

Obtain free DEM data of South China

Is there any free source of Digital elevation model of China with the resolution of 30 meters or better and vertical accuracy of +-5m. Something along those lines
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1answer
74 views

How to calculate and compare RMSE between DEM using different interpolation methods?

I have data from aerial photo, it was built from stereo photo so I have 3D information that I am using for the DEM. I extracted it into shapefile. I want to get RMSE (Root Mean Square Error) from ...
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1answer
48 views

Removing every second row and column cells from a raster file

I have a SRTM 3 arc second topography model (.tif file). If I remove every second row and column of cells from the grid, can it be said that the model becomes a 6 arc second? Or does SRTM 3 arc ...
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0answers
73 views

DEM / Basemap Alignment

The image below shows the problem I'm facing. I'm trying to align a DEM with the ArcMap Imagery Basemap. Unfortunately, I can't make them to perfectly align. I tried changing the coordinate system to ...
5
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2answers
105 views

DEM out of a shaded relief LiDAR?

I have a DEM built from LiDAR data and the file extension is .tif. When I open this file in ArcMap it seems to be a shaded relief DEM (see the screenshot below). It happens I want to visualize the ...
1
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1answer
55 views

Creating DEM from point data in CSV files using QGIS?

how can we create a DEM in QGIS from point data in CSV files? A similar problem was discussed here, using a shp-file. Our CSV's are too big, so that dxf2shp crashes. So we are looking for another way ...
2
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1answer
47 views

Georeferencing an oblique angle photograph in repeat-photograph studies

Backround: Aerial photography and remote sensing can be used to measure current land cover and recent land use change. However, these technologies are fairly recent and therefore time series are ...
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0answers
29 views

Individual tree extraction [duplicate]

I would like to extract individual trees in ArcMap 10.1. I have 1.3 meter resolution DSM data created from aerial images. I used Crown Height Model to extract tree heights (as attached file), but I am ...
1
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3answers
226 views

Converting DEM text file to tiff file in QGIS?

I am trying to convert a digital elevation model in txt file format to a raster file (tiff) with qgis. The file format is *.dat. The coordinate system is Gauss Krüger, Bessel, 5. meridian. First I ...
1
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1answer
67 views

Convert dem and geotiff to collada model with texture

I have a digital elevation model (dem) file with corresponding orthophoto in geotiff format. What I need to do is to create a 3D model of the terrain with textures (preferably in collada file). I ...
0
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2answers
73 views

Filling only the deepest sinks/depressions in a DEM

I am trying to come up with a workflow that will extract the location of surface mines from a DEM. My original thought was to fill the depressions in the DEM and then subtract the original DEM from ...
0
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1answer
31 views

Fixing Pixelation in DSM [duplicate]

I ran las dataset, then las to raster using max for DSM. Two and a half hours later I have 3 areas showing pixilation using higher level coloring. See enclosed image. I found on web that seamless ...
2
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0answers
42 views

Weird artefacts/pixels in QGIS-created shaded relief map

I'm working with 30m SRTM data on an terrain map of Cuba. I downloaded the necessary DEM files, merged them and went on to create the shaded relief map in QGIS 2.8 using Raster > Analyze > DEM (...
2
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1answer
95 views

Download of very detailed DEM files for Portugal?

Operating system: Windows 10, 64 bit. QGIS Version: 2.13.3 which I installed via the QGIS.org website. I need contour lines for a small area in Portugal. I saw a guide posted here: http://planet....
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0answers
20 views

Elevation data from floating point DEM in ArcGIS for Desktop? [duplicate]

I have acquired a DEM from local municipality. It is a float point DEM, and the elevation of each pixel is represented as simply "pixel value". What would be the correct work flow to convert this to ...
3
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2answers
380 views

Creating DEM from las file without using Lastools

I want to create a ground model from a *.las file. The LAStools are available in QGIS but limited in use (generation of black diagonal in result file), so I can't use this. In the GRASS tools I can ...
-2
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1answer
64 views

Expression into the raster calculator to invert DEM

I've made a DEM from first pass LiDAR data which I want to invert and run watershed segmentation and basin delineation over in order to hopefully extract tree canopy outlines and heights - I'm newish ...
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2answers
160 views

Trouble “extracting by mask” with a DEM layer and a shapefile?

I'm using ArcMap 10.2 and I'm currently trying to clip a county-wide DEM layer (.lyr file) down to a smaller area using a shapefile. The data frame coordinates system is set to US Feet which is what I ...
4
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1answer
53 views

The source of and possible solutions for DEM anomalies?

I am working with a DSM (Digital Surface Model) created using stereo-paired spot 6/7 satellite imagery. This DSM, and metrics derived from it will be used to create a Predictive Ecosystem Map (PEM). ...
2
votes
1answer
124 views

Reclassifying a DEM using ArcMap 10.1

I have a DEM that am reclassifying into two classes. One areas less than or equal to 1000 and the other areas greater than 1000. Am accomplishing this using the reclassify Tool in ArcMap 10.1. The ...
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1answer
52 views

Creating DEM from topography map in QGIS [duplicate]

For my geology diploma project I need to create DEM from topography map my professor gave me to use as a base map. The map is georeferenced. My idea was to draw lines over the izolines of the map, ...
3
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0answers
76 views

How to calculate best path between 2 points from a DEM in Qgis?

I'm analyzing the roads and paths of a region by calculating how effective the communication is in the region. First I calculated the shortest paths between the points using the actual road map. Now ...
2
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1answer
68 views

How to derive a hydrologically correct DEM from point shapefile using QGIS?

I used grass gis v.surf.rst function to interpolate a surface using vector points. But it is very difficult to find a optimum parameters to be used. I am still unable to develop a accurate terrain
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2answers
125 views

Filling up river corridors in a DEM

I'm currently working with a DEM (10 m x 10 m resolution) that has a lot of faulty elevation values in river corridors. In order to run a hydrodynamic model I'm trying to get the following done in an ...
2
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1answer
49 views

How to import a digital elevation model in Germany Gauss Krüger from .dat file?

i am very new to qgis. I want to create a hillshade file and also calculate the inclination. The structure of the digital elevation model data looks like this: 5390.0125 5659.9875 251.8 5390.0125 ...
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0answers
52 views

Stream Burning/DEM Reconditioning

I am conducting a regional study in the Midwest. I was wondering if stream burning would be necessary for this large region. I am using a 90 meter DEM. If stream burning is necessary, what should the ...
0
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1answer
100 views

How to find the height information from LiDAR point cloud data [duplicate]

I need to find the biophysical parameters(biomass) from the LiDAR point cloud data. For that I need the height of the trees from the data. Currently I am having the general height with respect to sea ...
1
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1answer
72 views

Free Digital Elevation (Terrain) Model of Europe or Germany

Is there any free (or not expensive) source of Digital elevation model of Europe or Germany with the resolution of 10 meters or better and vertical accuracy of +-5m or better?
0
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1answer
44 views

How do you identify cuttings / crevices from a DTM or DSM using ArcGIS?

I am trying to identify where cuttings and crevices exist by using a DTM or DSM. My ultimate aim is to find where roads and rail lines sit within a cutting i.e. the land either side of them is higher ...
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0answers
29 views

Creating tiling scheme to get multiple extents before gridding elevation data

Looking to create 1 degree by 1 degree tiles with pixel overlap to get extents before I start gridding. So basically I would like to have a shapefile of the tiling scheme with extents before having ...
3
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0answers
51 views

Building a DEM with both a raster and vector points [closed]

So I'm struggling here, trying to get a decent DEM for the Azores Islands because I want to include bathymetric data on it. I have a raster with elevation for the islands (land) with a 30 meter ...
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0answers
45 views

Generating continuous aspect surfaces from DEM with QGIS

I'm trying to extract aspect surfaces from different DEM sources at different resolutions in QGIS. I've had success working with SRTM-derived grids (3-arcseconds) and am trying to perform the same ...
1
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1answer
56 views

Extracting coordinates of a triangulation from DEM data

I'm working on the succinct representation of planar graphs and now I'm trying to obtain some datasets to test my results. I saw that Delaunay triangulations of elevation data can be a good source of ...
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0answers
14 views

Volume of free space between valleys using arcgis [duplicate]

I'm having DEM and I want to estimate volume of wastes that can be dumped in valley. For that I want to estimate volume of free space between valleys. How should I estimate volume of free space in ...
2
votes
1answer
31 views

Creating Data Elevation Model from two sources

I have 2 Data Elevation Models ( Aster with 30 m resolution and a DEM obtained by stereo with 4 m resolution ). Unfortunatly the DEM with high resolution contains a lot of no data value and some ...
4
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0answers
77 views

OS terrain 50: .vrt from zip files

I tried to follow what was suggested in How to use OS Terrain 50 in QGIS, but I got the following problem: in spite of being generally able to generate .vrt files using gdalbuildvrt from unzipped ....