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

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22 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
157 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 ...
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0answers
32 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 ...
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0answers
14 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, ...
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1answer
49 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 ...
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5answers
753 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 ...
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1answer
44 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
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1answer
293 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 ...
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1answer
57 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 ...
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0answers
36 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 ...
11
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1answer
2k 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 ...
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4answers
25k views

How to extract raster DEM elevations to vector attribute tables in ArcGIS 10?

I have an ArcMap 10 project with multiple layer groups. One layer is a raster DEM, another layer group is a bunch of vector shapefiles (including points, lines and polygons). The client wants all ...
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2answers
61 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
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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
43 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
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2answers
211 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.
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2answers
50 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 ...
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2answers
284 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 ...
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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 ...
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1answer
55 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
26 views

Performing DEM analysis?

My DEM elevation values varies from -255 to 81. What does the negative values imply? I have downloaded the dem from BHUVAN. About 90 % of values fall in negative category. How can I convert these ...
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0answers
29 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
37 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 ...
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0answers
55 views

SRTM DEM and satellite DEM fusion

I have a SRTM DEM and a DEM derived from satellite (Cartosat). Both the DEMs are registered perfectly. Now I want to carry out a DEM 'fusion' process to derive a higher quality output DEM. I am not ...
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3answers
292 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 ...
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5answers
220 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
22 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. ...
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1answer
73 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
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2answers
154 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
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2answers
218 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 ...
17
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2answers
599 views

How to create transparent hillshade?

I get elegant transparent hillshades via a combination gdal and convert. Compare to grey-based hillshade commonly used, such transparent hillshades are very cool because they can be placed between the ...
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0answers
149 views

Can the Phantom 3 Pro be used to capture aerial imagery for small site plans and to derive DEM?

I am curious if this consumer UAV can be used to capture imagery for further processing to stitch seamless imagery and to use as input into stereo/photogrametry software to create reasonably accurate ...
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2answers
715 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 ...
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0answers
34 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 ...
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1answer
53 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 ...
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2answers
48 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 ...
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3answers
383 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 ...
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4answers
7k 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 ...
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0answers
49 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
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1answer
586 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 ...
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2answers
428 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
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1answer
65 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
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1answer
312 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
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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?
9
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3answers
299 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
28 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. ...
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2answers
74 views

DEM with bathymetric contour lines in GRASS

I am trying to create a DEM from a bathymetric contour lines. Contours are in vector format and the elevation value is negative. To create the surface I have converted the contours in raster (v.to ...
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1answer
31 views

Where to download Mars DEMs and landcover?

I'm looking on the websites of the Mars Global Surveyor and the NASA sites, but all of the data is in jpeg or img form. Does anyone know where to find useful raster data sets for elevation and land ...
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1answer
258 views

DXF (points and lines) in QGIS - Doesnt import z coordinates

Trying to get to grips with QGIS, coming from a Mapinfo and Civil3D background. I have a DXF file with points (X,Y,Z) and lines. I want to open this in QGIS and use the interpolate plugin to create ...
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1answer
81 views

Hillshade with too big pixels

I digitized some maps with isolines every 4m. I created a DEM and the Hillshade. But the hillshade has big pixels. I use ArcGIS 10.3. Is there something to be look out for that I might have done ...