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

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4
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3answers
345 views

Which raster resolution (DEM) can I get out of lidar data with variable grid width?

I have ASCII files in *.xyz format and want to generate a DEM out of it. According to the information about the data the *.xyz files are containing variable grid widths - from 1 meter to 4 meter. ...
1
vote
1answer
142 views

How to make raster DEM from SHP with FME?

I have a Point Featureclass in an ESRI FGDB with 22 Million points. The points have a distance of 10m from each other.I would like to create a raster DEM using SAFE FME 2014. Looking at the ...
1
vote
0answers
291 views

How to fill empty pixel from DEM using QGIS?

Is it possible to fill empty pixel from DEM (hgt file)?) in QGIS ? When I load it, and zoom to a big scale, some pixel without any value appear. ( I have found a way using another software 3DEM on ...
2
votes
0answers
67 views

How to efficiently drape vector data over a DTM

I have ~100 million 2d vector topographic features (lines and polygons) in an Oracle 12c database. I have 20 billion xyz points in an Oracle database table as number types - the points cover the same ...
1
vote
2answers
206 views

Producing GIS data from large amount of ASCII DEM files?

I have just received a large amount of ASCII DEM files. In total 564 Files each containing 40,000 point data (22.560,000 Points). I would like to convert this into a point cloud with a view to ...
2
votes
1answer
1k views

QGIS 2.6 - Point Sampling Tool plugin producing empty shapefile

I use a DEM file (*.tif) and a points layer. My need is basic : getting the Z value for each point by extracting them from the DEM. Both layers correctly opened with QGIS 2.6. The DEM returns a Z ...
1
vote
1answer
2k views

Generating a Mesh from DTM

Are there any tools that can take a DTM, in asc or geotiff format and generate a mesh from this that can used in meshlab or similar software. I have asc DTM file that I need to convert to a ply mesh ...
2
votes
1answer
561 views

How to reproduce contour-style labeling with rasterVis::contourplot?

I am currently working with a digital elevation model (DEM) of Mt. Kilimanjaro, Tanzania. The referring raster grid can be downloaded from DIVA-GIS (Country: Tanzania; Subject: Elevation). After ...
2
votes
0answers
331 views

Error 5 Pixel type must be FLOAT32

I am trying to create a DEM from topographic contours vector. I have already sucessfully created a raster using the interpolation plugin. Firstly, I don't know why or how to ccontrol the output ...
2
votes
0answers
103 views

Extracting DEM from IFSAR

i have this IFSAR data (.img) and i dont know where to start. how do i extract DEM from this data? Do I need to go through a Remote Sensing software (ERDAS or ENVI) or i can simply use ArcGIS? and how ...
2
votes
1answer
75 views

Resolution of NED (National Elevation Dataset)

I downloaded some DEMs from the USGS with a resolution of 1/3 degrees for different areas in the US. Now I am looking at the files and saw that all DEMs have the same number of columns and rows. I ...
1
vote
0answers
70 views

How do I reduce contour intervals (i.e. from 50m contours to 10m contours) without using DEM?

I have shapefiles (lines) of contours having 50m intervals. How can I reduce the intervals to 10m without first converting the 50m contours to DEM?
2
votes
1answer
704 views

Gdal/QGIS resampling asc file

I have a DEM (.asc) file with a resolution of 1000 meters per pixel. Therefore the file has a lot of columns and rows. I would like to chance the resolution per pixel from 1000 to 3000 meters per ...
9
votes
2answers
259 views

Cleaning blocks pattern from urban LIDAR (blocks uplifted from streets)

We have a 1-meter LIDAR DEM from a city. A small subset can be downloaded from this link: This screenshot shows raw DEM with gray palette (darker belts are streets, and greyish and whitish ...
4
votes
1answer
133 views

Raster cells with no data being generated by las2dem?

Anyone has an idea where these lines (with no elevation data) come from? They are generated while using the las2dem tool from LAStools. What needs to be done to avoid this? The raw data (.las file) ...
2
votes
0answers
42 views

How can I manipulate the number of points visible according to scale?

I've gotten trillions of points extracted from a DEM and they are to be labelled. It's fine at scales such as 1:500 but it gets too cluttered especially if I need to make maps of this with scales up ...
5
votes
1answer
87 views

Curvature computation for different scales

I would like to assess terrain curvature, i.e. the 2nd derivative of a DEM, on different scales. The most common approach to curvature seems to be the one suggested by Zevenberg (1987) where a ...
2
votes
2answers
224 views

convert DTM txt file in geoTiff file

I have a DTM file, txt format, I would like to convert it into GeoTIFF, how can I do with the software grass? thanks ncols 1329 nrows 1152 xllcorner 1693884 yllcorner 5080341 ...
1
vote
1answer
325 views

Digital Elevation Model Resolution

While I creat flood areas using DEM in ArcGIS, Which parameters do I consider to determine DEM's pixel size and resolution?
8
votes
3answers
614 views

Handling mountain shadows when classifying Landsat 8

I'm trying to classify some area in northern Mongolia using Landsat 8 satellite images from 2013. Since the recordings were made in winter, the sun is very low at the acquisition time. Therefore there ...
4
votes
1answer
3k views

How to calculate and compare RMSE between two DEMs? [duplicate]

I'm doing a project based on using Lidar point cloud data and I have access to a DEM that cover all of Sweden. But my goal is to produce several DEMs covering a small area using different ...
2
votes
2answers
2k views

How to create DEM from Lidar point cloud data? [duplicate]

I'm using ArcMap and I want to create DEM(s) over an area to have different outputs depending on which settings/filters I put in. I have access to laser point cloud data as my input files. I've worked ...
1
vote
1answer
303 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 ...
4
votes
2answers
695 views

Stitching Bathymetry and DEM data together in ArcMap?

I have a DEM built from Lidar data and bathymetry survey points for a river which flows on the DEM surface. My understanding is that Lidar data is not able to capture bathymetry under the river flow....
4
votes
1answer
118 views

Problem of irregular contour from a DEM

I've created contour lines every 5 meters from a grid DEM with 5x5 meter of resolution. But strangely I've obtained that the contour lines are segmented and rich of lines that goes up and down, ...
19
votes
3answers
5k views

How to produce high-resolution DEMs from new Sentinel-1 data?

This is a general question relating to the new Sentinel-1 data. I'm interested in the potential for using this data to create high resolution DEMs in GIS (I use QGIS), to investigate archaeological ...
7
votes
2answers
15k 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: http://glcfapp.glcf.umd.edu:8080/esdi/index....
2
votes
1answer
231 views

How to convert different lidar data formats to raster DTM and measure its geographic position accuracy?

I'm trying to generate a DTM from lidar data and I'm new in the this field. I have different kind of files which describe the same area (different versions): *.dtm *.xyz *.xyz with variable grid ...
2
votes
2answers
168 views

Contour of single feature on QGIS

I'm trying to extract one single contour line at given elevation from a DEM. Taking into account that I want only one contour and not all contours with the given elevation, is there a way to do it in ...
1
vote
1answer
1k views

How to calculate the river slope for a lot of rivers automatically in ArcMap?

I'm working with ArcMap 10.2 and I'm pretty new in this area.. What I want to do is compute the river slope for a lot of rivers from a DTM...I know that there is a way to do it manually passing by ...
2
votes
0answers
35 views

infer the altitude from a DTM & finally provide it to point / evincere la altitudine da un DTM & finalmente fornirla a dei punti

I would like to complete a point vector's table with Z data. I am not able to take Z coordinate from a dtm (downloaded from http://www.regione.piemonte.it/geoscaweb/index.php?pgs2=0&pgs3=DTM10&...
2
votes
2answers
870 views

automatically geo- and ortho- rectify raw Landsat data using DEM

I have a dataset of 20 Landsat scenes (MSS, TM, ETM+) for 20 years (one scene per year). Scenes are in WGS 84, EPSG 32634 coordinate system and I can easily project = geometrically correct them to ...
3
votes
2answers
116 views

Digital Elevation Model and Shapefile not aligned in openWind

I have a digital elevation model and a shapefile containing point features for the location of wind turbines. These two layers appear to be aligned in QGIS but when I open them in openWind, they are ...
4
votes
1answer
3k views

How can I create a DEM from Point Data?

my boss gave me a small 3D-point-shape-file and asked me to make an DEM from it, wich I should put together with an older DEM of the same site, wich was made with Surfer. I created a raster-layer ...
3
votes
0answers
292 views

Command line tools to generate elevation profile from DEM + GPX/GeoJSON

I'm looking to generate elevation profiles from a number of GPX traces (which I also have GeoJSON conversions of). I have 20m resolution DEMs of the area, in GeoTIFF format. Ultimately I want to ...
5
votes
1answer
231 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
2answers
1k views

How to Clip a DEM and retain DEM format?

I have a DEM file that I downloaded from the internet. I am trying to clip it to reduce the file size. So far I have tried two different methods, but neither of them produces a clipped file in DEM ...
2
votes
2answers
465 views

QGIS, interpolate along an irregular shape or line to create a DEM

Before anyone marks this as a duplicate, hear me out. This question: Interpolation: irregular shape, merging DEM's asks my question but not for QGIS. Furthermore, the answer is vague and not ...
5
votes
1answer
232 views

Creating a point corresponding to the maximum elevation of a DEM [duplicate]

I am wondering how can I create a point corresponding to the maximum elevation value of a DEM. I mean, from the DEM I can easily get the maximum elevation. For the sake of a viewshed analysis, I would ...
1
vote
0answers
73 views

Inverting color ramp in legend

I have inverted the color ramp to display land surface elevation, now when I add a legend in print composer it shows the lowest value at the top and the highest at the bottom. See below: It is more ...
2
votes
0answers
45 views

Drawing boundary through DEM of glacier valley using ArcGIS for Desktop?

I want to calculate/draw the boundary extent in Glacier valley with the help of DEM. Can you please guide me which is the best tools in ArcGIS and steps to calculate.
5
votes
1answer
135 views

Intersection of a vector linestring and underlying DEM

Following is an screen-shot where ASTER DEM raster layer has been overlaid by a road linestring vector layer. I want to extract those DEM pixels which are lying exactly beneath the linestrings. I want ...
1
vote
0answers
32 views

Buffering/extrusion of a dem surface

I have a surface representing a DEM and i would like to add it some thickness. If i simply duplicate the surface and translate it down by my thickness, i get non uniform thickness, ie thinner where ...
1
vote
1answer
177 views

Reclassification of raster surface using ArcGIS for Desktop?

I have a raster surface with values ranging from 0 -100. I want to create a categorical classification (percentage categories of 5%, e.g. 0-5%, 6-10%...) and reclassify my surface into these ...
3
votes
0answers
63 views

3D distance and topography

I have a set of points and want to find out the nearest distance to a water body (poly lines) taking into account the terrain and get a surface distance calculation. I understand that the way is to ...
2
votes
1answer
68 views

QGIS vector layers do not match DEM?

I have a DEM (saved as a .tif) and, using QGIS, I want to clip the DEM using a vector mask. The function will not work. Am I missing critical step?
7
votes
2answers
225 views

Reducing elevation from DEM using ArcGIS for Desktop?

I am so curious how would I strip off elevation from the DEM. I don't know how I would explain it further but I have attached an image to clarify this. I wanted to eliminate the area shaded with ...
1
vote
0answers
21 views

Where is it possible to download a DEM for the Romanian east carpathians? [duplicate]

I'm quite new to GIS and have only done a few small tasks for Projects at University and the required data has always been provided. I am now struggling to find the specific DEM I need. Also other ...
1
vote
0answers
590 views

How to convert shapefiles into ascii grid .asc in QGIS?

I downloaded multiple zips that cover a small island from the Rhode Island Geographic Information System webpage, specifically the geographic files that make up Block Island. Here's the source: http:/...
2
votes
1answer
415 views

shapefile to gmt format

I have an ESRI shapefile of the contours of my study area, and I want to convert it into a format that is acceptable by GMT, so I can make an elevation map of my study area. Is that even possible? ...