Questions tagged [dem]

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

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6
votes
4answers
10k 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 ...
16
votes
7answers
35k views

Viewing LIDAR data (.las) in QGIS?

Is there an easy path to visualizing LIDAR data in QGIS? I have some USGS LIDAR data in .las format downloaded from http://lidar.cr.usgs.gov/. This means I have both the .las and metadata in .xml ...
2
votes
2answers
3k views

Modifying DEM elevation data in QGIS using a polygon

I've tried searching through the existing questions but am struggling to find a succinct answer to what I am trying to achieve. For background, I am running a flood model in TUFLOW to help support a ...
0
votes
1answer
99 views

QGIS 3.4 Stream delineation problem, lines running too far into ocean

I am using QGIS 3.4.4 Madeira version trying to delineate the stream and catchment areas of a small Bay in Honduras based on the technique of Hanz van der kwast tutorial "Stream and Catchment ...
1
vote
0answers
65 views

Extracting Ridges from DEM ALOS

I'm currently working on a forestry project for my thesis. It consists of the optimization of skids tracks planification using ALOS images. To this end I would like to extract obstacles such as steep ...
9
votes
2answers
3k views

Generating floodplain generation given river section polylines, flood level elevation points and DEM of land surface? [closed]

I am looking to generate flood plain polygons to represent 20 and 100 year flood zones, in the most accurate and efficient way possible, given the following datasets: River cross section polylines ...
0
votes
1answer
35 views

Slope is not consistent with the elevation of DEM and seems to be incorrect

I have a DEM image which shows the elevation is from approx. 81 to 103. I expected the slope should be 0-22m. However, the result from DEM-Terrain Model-Slope is from 2.5 to 13.2. Anyone knows why?
1
vote
1answer
79 views

Find higher elevation (10m) perpendicular point from stream network at regular interval

I have a stream network and for that network, I want to find the points at regular intervals which lie at 10m distance perpendicular from the stream.The final goal is to find the buffer of that 10m ...
1
vote
1answer
28 views

Adding height to dam in ArcGIS Desktop?

I'm having issues with flow direction in a reservoir heading in both directions. To try and correct this I think I need to add height to the portion of the DEM that currently represents the dam to ...
0
votes
0answers
29 views

Fixing sharp edges between GeoTIFF tiles? [duplicate]

I've downloaded a couple SRTM DEMS from http://srtm.csi.cgiar.org and when I load some of them into QGIS, there is a noticeable edge between 2 of the tiles (see image). Why does it happen? These are ...
0
votes
0answers
64 views

GdalDEM slope error in Jupyter

I try to calculate slope data. This is the DEM source https://www.earthenv.org/DEM Firstly, I translate data with gdal.Warp according to image UTM zone. Original image .bil extension so first I ...
6
votes
2answers
165 views

Raster antialiasing

I am looking for a way to antialias integer DEM data (hgt file) to float GeoTIFF. That way I want to avoid gdaldem hillshade artefact lines which you can see in this picture: I don't want to blur ...
1
vote
1answer
31 views

Applying same symbology to different DEMs?

I am using ArcScene and ran into this problem where I downloaded a couple of neighboring/bordering DEMs(in BIL format), imported them into the scene (as separate entities) and applied Base Heights so ...
2
votes
1answer
77 views

Mirrored Contours from DEM in QGIS

I am trying to create contours from a DEM in QGIS 3.4. I used the GDAL raster extraction contour tool. The contours are drawn correctly, but they are mirrored along the north line of the DEM (see ...
1
vote
0answers
102 views

QGIS Exporting Layout as Blank PDF?

I am trying to export my map layout in QGIS3.4.5 on OSX 10.14. I've made the layout look exactly how I want it to look, but whenever I export to PDF, the PDF file is just a blank white page. The ...
2
votes
1answer
64 views

sampling error using gdalwarp on a subsetted VRT?

I am currently trying to prepare an SRTM subset including height conversion from EGM96 to WGS84 using gdalwarp. I encountered some strange shifts in part of the image. Here is a reproducible example: ...
2
votes
0answers
158 views

Increasing zoom level in 3D View QGIS Desktop?

I would like to increase the zoom level for my mosaic raster image in the 3D View of QGIS Desktop 3.4.4. I made a mosaic out of four raster images downloaded through the STRM-plugin for DEM data. ...
1
vote
1answer
135 views

SAGA hydrology toolbox Error: select a library

Hi I am having trouble getting the SAGA hydrology toolbox running. Here when I try to fill sinks in the DEM a series of errors are flagged in the log file. This includes for 'select a library', 'DEM' ...
6
votes
1answer
275 views

Calculating shadow of trees with DEM in QGIS?

I have a DEM with a good precision (0,5 x 0,5 m/pix LiDAR) and I´m looking for the way to obtain a raster (or shapefile) with the shadow of the trees located in that place for a whole day (ideally ...
1
vote
0answers
113 views

Easy way in PyQGIS to convert a distance from meters to coordinates?

I am attempting to clip DEM rasters (USGS, in WGS 84) into a set of tiles measuring 2.56km on a side, in QGIS, using python. So far, it appears that gdal_translate is working for me, using a ...
1
vote
2answers
90 views

Visibility analysis with mask for non visible areas?

I have LiDAR data and I've made a Digital Surface Model (DSM): I've made a visibility analysis for 3 buildings with this model: My goal is to know from where the buildings are visible, not what do ...
2
votes
1answer
40 views

FME Surface Modeller “minimum number of points”

IN FME workbench 2016.1 I want to create a DEM from Multipatch-geometry contained in a geodatabase, for doing that I thought using the SurfaceModeller could work, where in SurfaceModeller I group the ...
0
votes
1answer
31 views

Converting IMG to BIL/HRD/BLW?

I'm trying to convert IMG data from USGS's 1/9 arc second DEM to something that Pathloss 5 can read. Is there a way to do so?
5
votes
1answer
238 views

OS terrain 50: .vrt from zip files [closed]

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 ....
0
votes
1answer
42 views

Extract height from DTM into attribute table of point layer [duplicate]

I am using ArcGIS Desktop 10.4 I have an empty point layer (100 random points) and a dtm. I was wondering how I would go about to get the height from the dtm underneath each point into the points ...
0
votes
0answers
40 views

Whitebox GAT branch depression big raster

I'm trying to run the tool Brunch depression form Whitebox GAT but the process doesn't work probably because the DEM is oversize For generate that raster i converted the single quadrant in the ...
1
vote
1answer
56 views

Highest point from DEM

I generated the next DEM abd Orthomosaic and I am interested in extract the highest point of each building, is there any workwflow that I could implement in QGIS or SAGAGIS
0
votes
0answers
35 views

Filling NoData around bridges in DEM

Is it possible to fill no data around bridges without pixels blurriness (see picture). I use Elevation Void fill function, also tried in qgis No data filling and Grassgis r.fillnulls. I know, that I ...
18
votes
8answers
8k views

What software to use for making digital elevation models from UAV aerial imagery?

I have a an unmanned aerial vehicle (UAV, also called a drone) and would like to use it to create a digital elevation model and orthomosaic over a smaller area (10 km2). My platform will be able to ...
6
votes
6answers
1k views

DEM generation from ASTER L1B imagery using FOSS

Is there any (photogrammetric or other) FOSS package to support the generation of a DEM from ASTER L1B products (i.e. combining the spectral bands 3N and 3B)? Are there any practical examples or/and ...
5
votes
2answers
475 views

Highest resolution Digital Elevation Model for the UK?

I need the most precise and highest resolution free digital elevation model for the UK. Would OS terrain 50 or ASTER GDEM be more suitable for view shed analysis?
2
votes
1answer
73 views

Translating vector by raster DEM data in QGIS?

I'm trying to follow the set of instructions here: https://twitter.com/imhere_asia/status/1023055838787690496 [EDIT] Pasting the instructions here for reference so people can avoid twitter. ...
2
votes
0answers
36 views

Channel network from high resolution DEM for flat areas

I'm working on channel network extraction from a LiDAR DEM (square grid max resolution 0,25 cm), and my area of study is vary flat with some part below the sea level. I applied the classical valley ...
1
vote
0answers
72 views

Difference between DEM raster in QGIS 2.18 and 3.4.4 [duplicate]

I came across a really strange problem. Untill today i always worked in QGIS 2.18. Now i wanted to upgraded to 3.4.4 ( it was already downloaded but hadn't used it yet) When opening my QGIS ...
0
votes
1answer
115 views

Determining length of roads that fall under low elevation using ArcGIS Desktop? [closed]

I am working on a project on sea level rise impacts of roads. Basically I need to determine length of roads that fall under low elevation (from 1m to 5m elevation). I have a DEM file and road ...
1
vote
1answer
357 views

Selecting lines affected by sea level rise?

I'm doing a part for my master's thesis where I'm trying to find out which sites located near the coasts of Sweden that will be affected by sea level rise. I got a DEM with height data and have to ...
0
votes
0answers
50 views

Creating 3D Local Scene using pointcloud, DSM, and orthomosaic from Drone in ArcGIS Pro?

I am trying to create a local 3D scene in ArcGIS Pro and display data fro drone flights. I have the orthomosaic from the flight as a .tif, the Digital Surface Model as a .tif, and my pointcloud from ...
13
votes
2answers
4k views

How to build an artificial 'dam' across a river?

I have a DEM. Created all files related to watershed including accumulation, direction, streams etc... I'm stuck creating a dam. I request you to please let me know how to build an artificial 'dam' ...
2
votes
1answer
168 views

Function or method in GEE that allows to fill sinks in Digital Elevation Models (DEM)

I would like to know if there is any function or method in Google Earth Engine (GEE) that allows to fill sinks in Digital Elevation Models (DEM) like the algorithms available in traditional GIS ...
2
votes
2answers
580 views

Get values of terrain elevation of roads in QGIS?

I have one DEM raster layer with elevation values and one vector layer of the roads; same size, extension and CRS. I want to do what this guy did here: http://youarealegend.blogspot.de/2012/07/...
1
vote
1answer
110 views

QGIS 3.4 and DEMto3D 2.3 Scaling Error

I'm having a scaling problem when using DEMto3D and extracting STL's for later manipulation. I have a merged TIFF file for Australia and am attempting to extract models of each state so I can print ...
0
votes
1answer
98 views

Extracting certain area from DEM using ArcGIS Desktop?

Using ArcGIS Desktop, how do I extract a certain area (uniform 1 km from the entire coastline) from a particular year's DEM image?
2
votes
2answers
108 views

Getting a flat surface from DSM for height calculation?

I have a DSM done trough photogrammetry with the software Agisoft Photoscan of a forestry experiment and I need to accomplish an analysis of the mean height from it. My problem is that the profile has ...
1
vote
0answers
33 views

Copy Raster for a Raster Mosiac with Function produces corrupted data

I am trying to export a ArcGIS raster mosaic dataset to a new raster that has a "Elevation Void Fill" function on it to fill holes in the data, but I am finding the function data is getting corrupted ...
3
votes
0answers
62 views

Problems with DEM exporting after Elevation Void Fill function use

I filled nodata values in DEM by Elevation Void Fill function, everything was ok, but when I exported it, the raster looks different (see picture above), how can I solve this problem? I also tried r....
2
votes
0answers
68 views

Importing several LiDAR (.las) files in GRASS using v.in.lidar?

I'm building a DEM of a terrain in GRASS and have 48 LiDAR (.las) files. I know I can do this by using r.in.lidar (including the list of files as a .txt) and then r.fillnulls However, I want to ...
0
votes
0answers
20 views

Assessing mapping accuracy of a DEM with different resolutions

I am mapping conical shaped depressions on the seafloor and would like to know at what resolution of the DEM is my mapping accuracy affected by. For example if I have a DEM of 7 metres, what does the ...
2
votes
1answer
527 views

Using SRTM DEM with 16 bit signed pixel type changes to 32 bit float when creating slope/aspect/curvature?

I have mosaiced 8 SRTM DEM tiles in order to get one raster layer of elevation. When I use "Mosaic to New Raster" tool I set as a pixel type format "16 bit signed" because this is the format that SRTM ...
0
votes
0answers
60 views

QGIS Display Attributes as Z Value for Point Shapefile?

I would like to create a state map that displays a 3D bar chart for each of 20 colleges (mapped as points) showing the percent share of engineering degrees earned by award level (i.e., assoc, ...
0
votes
0answers
72 views

Change detection using DEMs of difference and error quantification

Im currently working on a project in one of my seminars at university ("Advanced methods in natural hazard research"). We are modelling DEMs with Agisoft Photoscan using pictures from flume ...