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

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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 ...
3
votes
2answers
92 views

How to calculate the relative share of an area of a circle that has a slope >15% in Germany

I need to calculate the share of buildable land for the 15 major german cities within a 50 kilometer radius of the city center. Part 1 of the definition buildable is that the area must have a slope ...
15
votes
10answers
32k views

Converting XYZ files (with regularly spaced xy) to ESRI GRID format?

Normally consultants (LiDAR survey) provide me with data to my specifications; already in ESRI GRID or ASCII GRID format. This way LiDAR data can be easily used with ArcGIS. This time I only have xyz ...
7
votes
3answers
540 views

Is there a difference between the Planchon & Darboux and Wang and Liu depression filling algorithms? Other than speed?

Can anyone tell me, based on actual analytical experience, if there is a difference between these two depression filling algorithms, other than the speed at which they process and fill depressions ...
1
vote
1answer
47 views

Add DEM layer to Leaflet

I want to add a digital elevation model (DEM) layer to my leaflet map and access the height data through javascript, i.e. I cannot use .png files or qgis2webplugin but rather .tif or some compressed ...
2
votes
1answer
30 views

Applying base heights to raster is giving me different results

I have applied the DEM's base heights to both the raster image, the raster DEM, and a vector file. The DEM and vector file match up but the satellite image does not match up at all. Any suggestions ...
4
votes
2answers
109 views

Faster way to calculate slope between two points on DEM using ArcGIS for Desktop?

I'm a forester, and I do lots of work with LiDAR derived DEM's. I'm looking for a quick-and-easy tool to calculate the slope between two points. The application for this would be drawing a proposed ...
1
vote
0answers
18 views

“Select a tool” error Saga: Accumulated cost (isotropic)

I'm trying to run Saga's accumulated cost operation in QGIS on a DEM and set of raster destination points, but keep receiving an "Error: select a tool" in the log after a failed run. There are no ...
0
votes
0answers
17 views

QGIS asc to GeoTIFF error: “File short, can't read line 3687”

I tried to convert an asc file to GeoTIFF and I had the following error: ERROR 3: File short, can't read line 3687. ERROR 1: (..:)/mdt.asc, band 1: IReadBlock failed at X offset 0, Y offset 3687 ...
1
vote
0answers
24 views

Applying values to highest terminal segments in channel network using PostgreSQL?

I extracted a channel network from a dem but due to some technical difficulties the layer had some discontinuities. So after filling them, i suddenly realised that the Strahler orders it gave me were ...
1
vote
0answers
23 views

QGIS: How to create a crosstab using SAGA toolbox cross calssification and tabulation?

I am trying to use Cross classification and tabulation SAGA toolbox. I have a raster DEM file (14 classes) and raster file precipitation (13 classes). I want to do cross-tab - but I don't know how ...
2
votes
0answers
46 views

Draw raster on top of a Leaflet map

I want to implement a raster layer on top of a Leaflet map that includes the following functionalities: Digital Elevation Model (DEM) terrain height included in each raster cell GPS-Track (I use ...
1
vote
1answer
53 views

Raster calculator fails with large raster in QGIS

I'm working in QGIS 2.14.1 with a DEM ranging from 200 feet to 1600 feet elevation called "dem_3m_Zft1b" (geotiff, 16822 X 33349 cells, No-data =-9999) If I enter "dem_3m_Zft1b" > 0 in the ...
2
votes
1answer
33 views

How to calculate mean elevation in a DEM between a specific interval?

I have a DEM with different elevations between 100 m & 3828 m. I just want to calculate mean elevation higher than 1500 m? Can I do that?
3
votes
1answer
49 views

Scripts to automate conversion from DEM to contour shape files

I am using the DEM files in the Cornell CUGIR repository to build contour layers in QGIS. The problem I have is that while it is easy to do, it requires many manual steps in QGIS that are both ...
1
vote
1answer
37 views

Hillshade effect not working when no data is on screen

I'm working on a DEM and I selected hillshade effect to be active. The problem is that I can't get it to appear when a no-data area is shown on my screen. If I move the area just enough for the ...
4
votes
1answer
39 views

Grid size of a Digital Elevation Model developed from topographic surveyed elevation contour line?

I have generated a Digital Elevation Model from elevation contour line. I got these elevation contour line at 20 cm interval from DGPS survey. What would be the grid size of generated DEM in "m". ...
2
votes
0answers
33 views

Watershed delineation with meandering river

I'm using ArcGIS (Hydrology toolbox) for watershed delineation for a number of pour points, and I'm running into problems with very meandering rivers on extremely flat alluvial land (Amazon basin). ...
1
vote
0answers
39 views

SAGA GIS Channel network crash

So, i had this very weird bug while treating my dem data lately. I used SAGA to create flows channel networks on a dem i acquired a little while ago. Preprocessed it using sink route detection and ...
2
votes
1answer
29 views

contour lines/ basement contour extraction

My purpose: getting out area between elevation contours (like b/w 600m and 700m). The contours could either be elevation ones or the basement contours. I got elevation contours using spatial analyst ...
1
vote
1answer
44 views

How to do diagram block with open source software?

I would like to do a block diagram (topographic and geological representation). Is it possible to do this with QGIS (or other open source software), in Windows 7?
2
votes
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 ...
3
votes
1answer
43 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 ...
1
vote
1answer
2k views

Creating Cost Surface Raster for Least Cost Path Analysis?

I have a DEM raster and would like to carry out a cost path analysis. Among other factors such as slope, proximity rivers etc. I would also like to take elevation into consideration. According to ...
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
47 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
46 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 ...
1
vote
2answers
75 views

programmatic DEM downloads similar to landsat-util

I recently discovered landsat-util, and was wondering if there was an equivalent command-line application for global elevation data, (for data around 1 arcsecond resolution, preferably geotiff) or if ...
7
votes
2answers
13k views

Download new SRTM 30 meters

I read about the new version of the digital elevation model at 30 meters (SRTM 30 meters), but I can not find from were I can download it. some sources: ...
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
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 ...
2
votes
1answer
116 views

How to remove las2dem streaks from raster DEM?

I've created a series of DEM files using the las2dem tool from LAStools; however since I don't have a licensed version they have black streaks running across them. Does anyone know a good method for ...
0
votes
0answers
35 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 ...
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 ...
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
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 ...
0
votes
0answers
20 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
22 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 ...
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 ...
3
votes
1answer
485 views

converting vectors to raster (burning streams)

I converted my stream vector to a raster file (using polyline to raster conversion tool). I anticipated that I would get a No Data row in the raster file attribute table, so that I could use a ...
1
vote
1answer
274 views

Creating DEM from cross sections in ArcMap?

I have a DEM in arcmap and cross section of a river which flows on the Dem in Hecras. I now the cross sections are more accurate. I want to make a DEM from some of my cross sections and stitch it on ...
12
votes
4answers
8k views

Using SRTM Global DEM for Slope calculation?

I have downloaded SRTM GDEM (~90 km resolution). I am using ArcGIS 10. I have tried to use spatial analyst to compute for slope. However, I can not compute for the slope. The output values has ...
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 ...
3
votes
1answer
86 views

Whitebox GAT not starting under Windows 10 - General JAVA or Whitebox problem?

I am currently running the DEM preprocessing on a relatively large (50000 km2 at 30 m resolution) and steep DEM. The objective is to extract the stream network and some morphologic attributes (e.g., ...
2
votes
3answers
1k views

Advantage of Digital Elevation Model (DEM) in Agriculture?

I have given the task to create Digital Elevation Model (DEM)'s of an agricultural area. I am programmer with Computer Science background and very new to GIS can anyone explain what is advantage of ...
0
votes
1answer
40 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