Digital Elevation Model (DEM), which could be a Digital Terrain Model (DTM) or a Digital Surface Model (DSM).

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2answers
302 views

Masking out places with elevation below 5 m from a DEM

I have a DEM of a study region; I want to modify the DEM in order to reflect the coastline outlook when the sea level was 5 meters higher than today. What I have done so far is to use 'Raster ...
0
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0answers
28 views

Is there an existing tool or plugin to automate the elevation versus volume relationship of a dem within a user provided polygon

I often need to obtain the elevation versus volume data for a proposed basin site but have not found a truly automated solution. I would simply like to create a bounding contour polygon of the DEM ...
0
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1answer
56 views

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

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 5 m elevation). I have a DEM file and road shape ...
2
votes
1answer
71 views

Calculating slope for points with downhill slopes rendered as negatives in ArcGIS

I have a DEM and a series of points. I'd like to measure the change in slope along the series of points. Distinguishing between uphill and downhill slopes matter to me, and ArcGIS' slope function ...
1
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3answers
338 views

Where can I download a free DEM for Scotland, UK?

I need a DEM file for Scotland, UK. Do you know where I can get it from for free? I need to create a watershed for an area of study. Thanks
2
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1answer
857 views

How to know if flow accumulation map reflects true catchment areas?

I have calculated flow accumulation (img file) using this DEM (img file), which is 0.5 degree resolution, using arcmap. I am wondering if the cell accumulation value can directly be translated into ...
1
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0answers
24 views

line from min to max of a digital elevation model

I have some geometries as multipolygons and a dem (digital elevation model). I need a line from the max value to the lowest value of the dem for every multipolygon. Is qgis a tool i could use or do i ...
9
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7answers
9k views

Open source tool to convert a DEM to a 3D model

I would like to convert a DEM (Digitial Elevation Model) file (e.g. from SRTM) into a 3D model that I can then edit with regular 3D modeling tools (e.g. Meshlab/Blender/etc.). However I'm using Ubuntu ...
0
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1answer
132 views

How to extract points from a Digital Elevation Model in ArcGIS 10.1?

More specifically my question would be if there is a way to create a grid over the digital elevation model in GIS and extract points, or elevational data, from the intersecting points of the grid? I ...
0
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0answers
55 views

Calculating slope from elevation returns hole when using ST_Slope in PostGIS

I have rasters from the National Elevation Dataset loaded into a PostGRES database and am using the built-in function ST_Slope to calculate the slope. However these contain many holes where there is ...
1
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0answers
347 views

Processing LAS dataset in QGIS 2.8.2

I need to extract DEM from LIDAR dataset in QGIS 2.8.2. I have installed LAS tools in QGIS. I cannot configure my LAStools because I do not get Processing-->Options and Configuration and instead I get ...
1
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0answers
64 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
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0answers
25 views

Another Z-Factor Challenge

I've been working on a DEM, trying to calculate the slope. I have it in WGS_1984 and re-projected into NAD_1983_MTM_8, my preferred projection for this project. Every time I run the slope tool, ...
1
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1answer
122 views

Is it better to take the elevation of a GPS unit or that of a Digital Elevation Model?

When searching of gps routes in wikiloc, for the trailrunning race "Transvulcania" I have several routes to look. I downloaded a lot, but every route has a distance between 71 kilometers and 74 ...
13
votes
5answers
842 views

Dikes extraction from DEM

I do have DEM of 1x1 meter and original LiDAR point cloud in .las, that DEM is made of. I need to extract river dikes (highest points of the dikes) to vector feature (point, polyline). Any idea for ...
0
votes
1answer
69 views

ArcGIS Raster To Multipoint Mac/OSX alternative

Is there an alternative to the ArcGIS Raster To Multipoint tool for Macs? The VIP thinning method is particularly of use. A comparative point cloud thinning/simplification tool to this would just as ...
4
votes
1answer
308 views

How to extract most probable flow line from multiple lines?

I have to apply uncertainty principle to computing flow accumulation using Monte Carlo method. I generate raster with random numbers which represents mistakes in creating DEM. Then I apply those ...
1
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1answer
125 views

Getting aspect and reclassifying raster files using Python in a loop

By using Python in PythonWin 2.7.3, I tried to obtain aspect files of a list of raster files in a folder(called database_Dem20) and save it to another folder, database_Dem20/testOutput. In the same ...
1
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0answers
57 views

How to interpolate a Raster DTM

I have a GeoTIFF DTM produced from Agisoft Photoscan at 0.05 m resolution. However the interpolation used by the program to remove the riparian vegetation has used points from the channel, thus ...
16
votes
1answer
3k 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 ...
0
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2answers
274 views

Reversing Extract by Mask in ArcGIS for Desktop? [duplicate]

I have a DEM and I want to apply some tools to it (fill and others). In my DEM I've zones (drawn as mask) that need to be exlcluded from that processing. I don't want to apply the processing to the ...
9
votes
2answers
1k views

What is the smallest contour interval possible when derived from a DTM?

I am converting a 2m DTM to contours, and would like to have the smallest interval possible. Is there a theoretical limit, or even a rule of thumb for defining contour intervals based on the ...
1
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1answer
83 views

Merging USGS DEM files in ArcMap?

I'm trying to merge my DEM files into 2 separate files, one will have 4 files and the other will have 3. I've been reading every post from when someone asked this before for over an hour and I'm still ...
4
votes
2answers
319 views

Interpolate Temperature Using DEM

I want to "co-interpolate" temperature with DEM. I have SRTM 90m aggregated to 1km and I want to "co-interpolate" my DEM with points with temperature data. How do I do this? I am using ArcGIS 10.
0
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2answers
76 views

QGIS - Edit Surface DEM to Add Buildings

Okay, let me start by saying I'm no expert in QGIS, I'm more into engineering. I'm building a 2D hydraulic model and I would like to add the building footprints (elevated) to my DEM, so flow will go ...
4
votes
2answers
334 views

DEM local adjustments - terraforming

I'm looking for software that can perform local adjustments in DEMs with tools similar to paintbrushes used in graphics editing programs but streamlined to respect geomorphology. To give you an idea ...
12
votes
2answers
3k 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 ...
0
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1answer
83 views

Understanding InSAR interferometry?

I understand that the result of InSAR interferometry yields a LoS deformation and if deformation in the vertical or horizontal is to be computed, it should require additional gps observations at the ...
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0answers
34 views

Merging DEM files using PostGIS

I have several DEM files and I want to merge them to create a mosaic. I found the St_Union(raster) or St_MemUnion(raster) functions but I don't know how to use them. Are there any other solutions?
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0answers
90 views

From DEM to Topographic Wetness Index in SAGA GIS

I have DEM in GeoTIFF format and I wish to calculate Topographic Wetness Index in SAGA GIS. TWI tool in SAGA GIS expects that user provides two values - 'slope' and 'catchment area'. Since there's ...
8
votes
3answers
456 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 ...
0
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5answers
307 views

How to create 10m DEM from 30m DEM?

I am not regularly working in raster analysis. I have a 30M DEM and I would like to create a 10 DEM out of that. Is it possible to do this using QGIS? and How? EDIT: (I understand that a sub ...
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0answers
25 views

Export of a Raster Not Preserving Color [duplicate]

I'm trying to make a pretty shaded relief map using the technique described here. I've done this process several times in the past without any problems but today am perplexed about what is going on. ...
1
vote
1answer
110 views

How to find the coordinates of the lowest point in a polygon

I am working in QGIS 2.6. I have a file of several polygons and I want for each one, to find the lowest point (where is it located and its elevation). I am using "Grid statistics for polygons" which ...
2
votes
2answers
202 views

Does a SRTM DEM image show details such as fields?

I'm working through the QGIS Training Manual where I have a step to get ... ... raster images (SRTM DEM) which cover the region you have selected for your course. SRTM DEM can be ...
2
votes
2answers
228 views

Creating basic DEM file with flat geometry in ArcGIS Desktop?

I want to create a basic DEM file in .ascii format which will just be a rectangular grid and with no slope i.e same elevation at every cell. Please provide information on how to achieve this. I am ...
5
votes
2answers
815 views

How to extract coordinates & elevations of boundary cells of DEM?

I am using a 50mx50m grid irregular shaped DEM file. I have to work on the boundary conditions. How do i extract the cell locations ( in x,y coordinate ) along the boundary edge and consequently ...
0
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0answers
63 views

Calclulate the shade from a DSM and from sun elevation and azimuth angle

I have a mosaic of about 5000 tiles of aerial orthophotgraphy taken at different dates and thus with different sun angles. Furthermore, I have a Digital Surface Model (1 m resolution). My goal is to ...
1
vote
1answer
149 views

Merging USGS DEMs in ArcMap?

I've downloaded some USGS DEMs from the National Map, which appear to be .adf files. I can open them in ArcMap 10.2, but I need to merge them into a single mosaic. To do this, I've created a raster ...
1
vote
2answers
93 views

Classifying DEM using Height Differences in ArcGIS ModelBuilder?

I would like to classify DEM into some classes, into a shp file with equal intervals of 200m (0-200m, 200-400m, 400-600m... 3400-3600m, higher than 3600m), by using Model Builder in ArcGIS 10.2. For ...
2
votes
3answers
1k views

Ways to extract DEM for urban areas using Google Maps?

Is Google maps' elevation API suitable to obtain the high resolution elevation data for areas that have 3D building such as Manhattan? Would the API for example yield a significant different value on ...
29
votes
4answers
9k views

How to smooth a DEM?

I have a SRTM DEM and I want to create a shaded relief from it. I created the shaded relief in GRASS and the result is very nice, but a little rough becouse the area is near flat and the DEM is 90m in ...
0
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0answers
114 views

World DEM vs ASTER Digital Elevation Models accuracy

I use DEM essentially to create surfaces on AutoCAD Civil 3D and then to create terrain profile views. I have been using mainly ASTER imagery from which I extract 2m contour lines in QGis and then ...
2
votes
1answer
876 views

How to get Drainage Divide and Streams from DTM

Does anyone know how you can get a map like this attached, having the digital terrain model? I'm sorry, but I do not know what is the exact technical term in English for them. I hope you understand ...
1
vote
2answers
615 views

DEM/Raster Peak and Valley identification and/or elimination (non-generalization)

I am an curious is there is a tool or process that can identify and/or eliminate obvious peaks and valleys in a DEM. I have looked into smoothing but I am interested in keeping the original sharpness ...
2
votes
1answer
227 views

Relationship between contour interval and spatial resolution of a generated DEM

If I have contour lines with interval say 10, 5, or 2 (etc.), and I generated a DEM from them, what is the relationship between between the contour interval and the resolution of the DEM? Irrespective ...
2
votes
1answer
401 views

How to remove strange gdaldem hillshade artifacts?

I've downloaded 9 chunks of 1 arc-second NED in IMG format from the National Map. I'm trying to create a hillshade from them. I'm using: GDAL 1.10.0, released 2013/04/24 First, I combine them and ...
4
votes
6answers
3k views

shadow simulation from buildings [duplicate]

is it possible to use hillshade function in ArcMap to calculate shadow areas of buildings or simulate shadows of buildings, using DSM of the buildings and the sun angle and azimuth?
10
votes
3answers
404 views

How to create composite hillshade?

The concept of composite hillshade is to combine multiple hillshades with different sunlight orientation to avoid blind spot. It requires to merge 3 hillshades images with 315⁰ (NW sunlight, default ...
0
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0answers
31 views

change from NAD 1983 to some PCS?

I want to ask how to change the coordinate system from NAD 1983 to some Projected coordinate system. I tried to change this DEM file to WGS 1984 (all of them) but when I did that my scale becomes 1:4. ...