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

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35 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?
0
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0answers
110 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
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3answers
542 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
366 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
26 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
129 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
223 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
238 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 ...
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2answers
840 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
71 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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2answers
130 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
2k 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
10k 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
154 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 ...
3
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1answer
1k 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
710 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
332 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
431 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 ...
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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?
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3answers
449 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
33 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. ...
0
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2answers
129 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
133 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 ...
0
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1answer
493 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
101 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 ...
2
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1answer
723 views

Extract elevation data from Landsat / MODIS imagery?

Just curious, have anyone tried to extract elevation data from LANDSAT or MODIS imagery? So far, I came across one journal by Toutin who did so using adjacent LANDSAT 7 imageries. Results seem pretty ...
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1answer
1k views

“Topo to Raster” tool for QGIS?

is there any analogue of the ArcGIS "topo to raster" tool in QGIS? I need to creates surfaces from shp for some cases from points and for some from lines and this instrument is very convenient.
1
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1answer
970 views

Can we create topographical map of private land using GPS elevation data?

Is there a way to create a relatively precise topographical map of a private land using GPS elevation data? As the land is a little bit over 100,000 square meters, the available regional topographical ...
1
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1answer
25 views

Does Scimap work with QGIS?

Does anybody know if Scimap ( http://www.scimap.org.uk ) works with QGIS? I know it is supposed to operate with ArcGIS and SAGA but as I am very much a beginner with QGIS I would like to know if its ...
2
votes
1answer
62 views

How to average gdal_hillshades?

For some unknow reason, my average of 3 hillshades is very dark : gdaldem hillshade input.tif hillshades_C.tmp.tif -s 111120 -z 5 -az 315 -alt 60 -compute_edges gdaldem hillshade input.tif ...
3
votes
0answers
53 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 ...
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0answers
123 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 ...
4
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1answer
197 views

How to use SRTM Global DEM for Aspect calculation?

I need to derive a raster representing aspect for North America (from STRM data, originally in geographic lat/long). In most projections, true north is only map north along eg the central meridian so ...
2
votes
1answer
312 views

Creating DTM for two surfaces with point data and calculating volume between them using ArcGIS Desktop?

I have point data for a ground surface level which is captured in a grid of 35m spacings. I also have point data for the new surface level after soil has been removed which is captured at random ...
2
votes
1answer
208 views

merge two DEMs of different resolutions? [duplicate]

I have two DEMs, the first one is in 30 meters of résolution and the second: 5 meters, and will like if there is a possibility of merging them to extend the area where I do my research?
1
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0answers
367 views

Convert contour lines to DEM in ArcGIS [closed]

I've been trying without success to convert contour lines to DEM (Converting to spot heights is also a possible solution but I have not found a way for that either) using ArcGIS 10.2 (Advanced ...
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5answers
1k views

Elevation correction ASTER GDEM2 (+10m)

My ASTER GDEM2 has a average elevation error of -10m for my area. (I testet it using 90 defferential GPS reference points and compared it with old Topo25, SRTM, and GoogleMaps). I would like to ...
0
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0answers
404 views

How to mosaic to new raster for multiple DEM tiles?

I took some DEM files and turned them into raster .tif files, i then tried to Mosaic them together using the mosaic to new raster tool and i keep getting two problems consistently, there seems to ...
0
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1answer
2k views

Creating Digital Terrain Model from Digital Elevation Model using ArcGIS for Desktop? [closed]

I have a DEM and I want to create a DTM from that DEM. Is it possible to do this in ArcGIS?
0
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1answer
919 views

How to remove negative values from DEM using ArcGIS for Desktop?

i'm using (ArcGIS 10.1) and i want to remove a negative values from DTM in order to keep just a ground topographic surface.
2
votes
2answers
430 views

Classifying DEM according to elevation in R?

r<-raster("DEM.tif") How to do the classification based on every ten meters for example and have different colors too?
2
votes
1answer
123 views

Automatically adding Z-values from a DEM to an already created polygon

We have excavated a very large 5.000 year old fish fence, which was documented by photogrammetry, and is now being digitized. I started digitizing the orthophoto in QGIS and everything is cool. Now ...
0
votes
1answer
56 views

Intermediate files disappear in ArcGIS 10.1

I am working with ArcGIS 10.1 creating some slope and aspect files. I do this: DEM_park = ExtractByMask(mosaic_name, park_area) and it creates the DEM_park file in a default gdb with a default ...
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3answers
645 views

Import DEM into PostGIS for QGIS

I'm a complete GIS newbie so sorry if I'm using the wrong terminology in searching for a solution to this... I'm trying to import a DEM into PostGIS and display it in QGIS. The data is from the EU-DEM ...
1
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0answers
75 views

How to fit Google Earth satellite image to UK OS 50 DEM

I have extracted a DEM tile from the UK Ordnance Survey's free OS Terrain 50 dataset The tile contains spot heights for a grid comprising 51 nodes (West to East) by 51 nodes (North to South) with ...
3
votes
1answer
624 views

DEM Stream Burning

I would like to ask you guys how would i burn streams in DEM the following images will help understand what I would like to do. this is my DEM and the blue lines are my rivers. However, when I ...
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2answers
64 views

Why QGIS Raster clipper does not work on reprojected layers?

I try to clip a hillshade raster and I get this error. The hillshade was the result of a reprojected DEM from WGS84 to WGS84UTM. When I to clip the hillshade or even the reprojected DEM, I get the ...
2
votes
1answer
86 views

What exactly does hill shade or Shaded relief , if performed on SRTM DEM will output?

Two questions actually. Does shaded relief or hill shade outputs mean "expelling of shadows"? For a vast country like India, how to prepare a map from SRTM DEM, which does not have any shadow ...
1
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2answers
652 views

How to properly get the slope from an ASTER DEM in QGIS?

I have inserter a raster dem layer from ASTER satellite and I want to get a raster that has the slope of the area. I use terrain analysis > slope but the output is so wrong. Why is that? here is the ...
9
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4answers
4k views

Definitive source for downloading DEM data

USGS has been moving towards serving data through The National Map Viewer. They have several WMServices through their website that serve elevation data to the public (hillshade & DEM). The ...