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

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2
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1answer
33 views

How to calculate the right area in polygons with help of DEM?

I have used infra red photos to identify territories in Norway where I have drawn polygons for different vegetation. I wonder if there is a way to use the polygons with elevation data to get the exact ...
1
vote
1answer
30 views

5x5 raster filter in ArcGIS?

Normally, I am using the 3x3 lowpass filter if I need to filter a DEM. However in one case, for better results in curvature calculations, I would like to do a 5x5 filtering. How is this possible in ...
3
votes
1answer
36 views

Do outputs (shp, dwg) inherit vertical datum from input (las) files?

I'm working in ArcMap. I pulled LiDAR data off earth explorer and created a DEM with the LiDAR data. I then created contours as a SHP file and exported to DWG (CAD). I was asked if the CAD file's ...
0
votes
0answers
34 views

Is it valid to resample a raster from 1m to 3 feet?

I know that in general it is not a good idea to up-sample. I am curious if it would still be be a "bad idea" with a minor change like this from 1m resolution to 3 feet? Going to 3 feet would not ...
0
votes
1answer
46 views

Get Elevation of XY points [duplicate]

I am working with ArcMap 10.3. I have imported DEM files. When I imported the files they had the extension of .DDF. I would now like to be able to take a list of XY coordinates and, for lack of a ...
0
votes
1answer
32 views

How can I blend DEM rasters with GDAL?

I have several DEM rasters in different projections and at different resolutions. The rasters are not rectangular, but they have appropriate NoData values. They overlap enough that I should be able ...
1
vote
1answer
45 views

How to speed up raster2pgsql?

I'm trying to upload a 37 GB raster dataset to PostGIS. The raster is out-of-db (-R option), so the actual pixel values are not stored in PostGIS. I'm using this command: raster2pgsql -s 25833 -C -I ...
7
votes
4answers
268 views

Extracting Values to Points without ArcGIS Spatial Analyst?

I have a raster DEM & multiple points. I want to determine the DEM elevation at each point. Other than manually examining the DEM at each point, (very time consuming with lots of points) is ...
2
votes
2answers
122 views

Where is the nviz tool in qgis 2.14 with GRASS 7.0.3?

I hope Im not blind but I looked in the grass tools (modules) and qgis plugins but couldnt find it. When i try to run nviz from GRASS the whole programme chrashes just before concluding. Its a ...
0
votes
1answer
30 views

Seeking low-resolution DEM of California?

I'm trying to create a 3D model of California (which I'll manipulate in Blender) at a fairly low resolution — just enough for large features (like Mt. Tamalpais, Coronado, etc.) to be legible. ...
0
votes
0answers
18 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 ...
0
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0answers
34 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
votes
3answers
134 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 ...
1
vote
0answers
21 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 ...
1
vote
2answers
51 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 ...
3
votes
1answer
42 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
votes
0answers
25 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 ...
0
votes
0answers
18 views

Dynamic style for DSM layers in geoserver

I have lots of raster layers to show DSM under GeoServer 2.8.2. The input file is the one band TIF served with ImagePyramid plugin. Could I set a dynamic style which related with min and max values ...
1
vote
0answers
21 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 ...
1
vote
1answer
37 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 ...
0
votes
0answers
51 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
votes
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
0
votes
1answer
37 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
0
votes
1answer
49 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 ...
0
votes
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 ...
1
vote
0answers
66 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
votes
2answers
93 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
vote
1answer
51 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 ...
1
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0answers
27 views

Connect a photo and a DEM using landscape features

I'm helping with an image retake study in Alaska, we have historical (up to 100 years old) photos of the landscape (with lat/long) and we'll be retaking photos this year at the same locations. The ...
1
vote
0answers
28 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
vote
3answers
145 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
vote
1answer
44 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
votes
2answers
58 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
votes
1answer
30 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
votes
0answers
33 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
votes
1answer
65 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: ...
0
votes
0answers
19 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
votes
2answers
252 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
votes
1answer
60 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 ...
1
vote
2answers
94 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
votes
1answer
49 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
100 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 ...
1
vote
1answer
49 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
votes
0answers
63 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
votes
1answer
58 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
1
vote
2answers
83 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
votes
1answer
47 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 ...
0
votes
0answers
36 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
votes
1answer
86 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
vote
1answer
55 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?