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

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1answer
143 views

How to find locations for hydro power using raster analysis?

I have a stream network and DEM file both in raster format. I need to extract values from DEM to stream network. For the analysis in stream network after that, I need to find out the places for hydro ...
1
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1answer
171 views

Input data format and read multiple files into Grass 6.4.1

I am trying to read in multiple (hundreds, thousand) LiDAR ascii files into Grass. They contain elevation data. I think I have managed one, and I can make a map of elevations, using File, Import ...
9
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3answers
568 views

How to extract breaklines from a given DEM?

Breaklines are very useful for describing a terrain - for example to build an exact TIN. My question is, how to extract these breaklines from a given DEM? I calculated the curvature (vertical) - ...
6
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1answer
2k views

Python Script for getting elevation difference between two points

I have several stream segments 1000 Km long. I need to find the elevation difference between two consecutive points of distance 1 Km starting from the upstream to downstream. How can I get the ...
5
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3answers
2k views

How to transform GPX-tracks into elevation-tracks with any GIS?

I have a GPS track in GPX format available from a recent bike tour and I need and want to do some analysis on the tracks. I'm wondering whether there is any way to transform the GPX data into an ...
4
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1answer
142 views

Shapefile and DEM: check rivers behaviour

I'm working with shapefiles representing rivers (rivers.shp), and DEM for the terrain elevation (terrain.tif). Basically, I want to check that my rivers (stored as polylines in my shapefile) behave ...
3
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1answer
515 views

TMS or WMS source(s) for DEM data tiles?

I'm spinning my wheels trying to find an existing, free source for TMS or WMS elevation data that doesn't involve a long-winded clickabout or an emailed url. This question has a similar purpose, but ...
0
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1answer
499 views

min and max values are not correctly calculated for DEM

I'm working with DEM in QGIS and need to know the min and max values of my data. In the Properties window, under the Metadata tab, the statistics section shows such values. However, I usually find ...
3
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1answer
2k views

Convert DEM to STL (3D Printer Format)

I have a DEM in ArcGIS 10.1 that I would like to get into STL format for a 3D printer. Does anyone know some software that will allow me to make this conversion? I have to use the STL format because ...
3
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1answer
529 views

Watershed extraction using different DEM tiles

I would like to extract the watersheds for a particular area using QGIS. However, I only have Aster 30m DEMs to work with, each tile covering one degree square. The problem is that I need to use ...
3
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1answer
155 views

Compute global DEM topographic indices and compromise projections

I would like to compute global topographic indices based on SRTM elevation data. These indices are computed along river/channel networks extracted from a DEM and are a functions of both local slope ...
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0answers
127 views

gdal_merge.py aligns incorrectly at the seam of two GeoTiffs

I am trying to merge four GeoTiffs from the National Elevation Dataset (EPSG: 4269) into a 2x2 DEM using gdal_merge.py. For some reason, when it merges the upper two NED rasters, gdal produces a seam ...
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1answer
251 views

Polyline ZM: automatic vertex height errors correction

Paolo I've got many rivers (polylines ZM) with a lot of height errors in Polylines 'vertices. Vertices' Z errors are not all equal in height (i.e. they are not all at zero height). I must create a TIN ...
2
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1answer
359 views

Compare two Digital Elevation Model (DEM)

I would like to know what's the best method(s) to compare two DEMs without using any GUI soft like QGIS or ArcGIS. I'd like to do it in Python or C++, with GDAL or other similar lib. Does calculating ...
2
votes
4answers
642 views

What could cause garbage hillshade output

I've used Hillshade successfully in the past, but for this DEM I keep getting a weird output. It's a 30-meter TIFF downloaded from the National Elevation Dataset. And this is what the output looks ...
0
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1answer
117 views

Correlation and terrain databases [duplicate]

I would like to know what kind of computation I could perform on a terrain database. I'm making terrain for VBS2 from raw data (shp files and DTM Elevation files) and then I'd like to be able to check ...
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2answers
2k views

How to use SRTM DEM files for shaded relief in ArcMap?

I would like to create a nice shaded relief for France using SRTM3 data. Most of the threads on the subject are from awhile ago, when ArcMap was not able to import these without changing the file ...
0
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1answer
501 views

How to calculate surface area of highland region using DEM with ArcGIS (ArcEditor)? [duplicate]

Am shyaka from Rwanda. I use GIS tools and have all required data to perform or calculate surface area from the polygons that have been given by GPS (Trimble) with ArcPad 8. I originate from a high ...
3
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2answers
325 views

Where to download 10m (1/3 arc-second) DEMs?

I'm looking for some of the 10m DEM to fill in the white Quad areas. Do you know where of can I find them? These 10 DEMs we have are actually coming from the NRCS Geospatial Dataway. I believe they ...
4
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2answers
254 views

Autocorrelated DEM with QGIS or Grass

I was wondering if there is a way to make an Autocorrelated DEM within QGIS or Grass. I am looking to do this with stereo aerial photography. I am able to do this with a number of COTS tools, but I ...
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2answers
905 views

What software is available on OSX for working with DEMs?

I have several adjacent DEM files and would like to combine them into a mosaic and then export to DEM and TXT. I know a Windows solution is to use MICRODEM but before installing Windows 7 I would like ...
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1answer
203 views

How to apply DEM elevation adjustment parameters?

I have a nice DEM, created from UAV data, which I want to process further in QGIS, my platform of first choice. In order to represent the evelation of each pixel correctly, I have to adjust the ...
3
votes
1answer
395 views

“topo to raster” tool

is there any analogue of "topo to raster" tool (ArcGIS) 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.
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2answers
118 views

viewshed analysis for observers wearing visors?

I'm starting with a DEM, and looking to identify every point that can be directly "seen" from any point in a particular polygon on an overlaid layer defining an area on that DEM - like any other ...
3
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0answers
46 views

Adjacent DEM files have narrow triangular gaps when joined

Newbie here. I've downloaded several DEM files from GeoCommunity which correspond to adjacent regions. When I join them together to form a larger relief map there are triangular 'gaps' on all four ...
4
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2answers
543 views

Retrieving average building height in urban areas

I am looking for a way to collect data on the height profile of some cities over time. I don't need to produce a detailed 3D reconstruction of cities, nor do I need to detect and measure individual ...
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2answers
866 views

Elevation difference map using two DEM

I am studying glacier mass balance and have ASTER and SRTM DEMs. I want to make an elevation/volume change image such that it graphically represents changes in elevation difference in various parts of ...
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0answers
41 views

How to extract elevation data from DEM along a polyline [duplicate]

I've been trying to use qGIS to extract and save as an attribute the data elevation along a line, knowing that something similar is available in ArcGIS using the Spatial Analysis tool. So far, ...
3
votes
2answers
342 views

Create hachures from DEM in ArcGIS 10.1

I have created contour lines from DEM and now I need to create hachures/bergstrich for them. I believe that spatial analyst should solve this, but I'm not used to it and I didint found any similar ...
5
votes
3answers
956 views

How to drape a simple jpeg image over dem of some area?

How can we drape a simple jpeg image which doesnot have any geo referencing information over the digital elevation model in order to visualize it in 3D in QGIS?
2
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1answer
550 views

Calculating mean upslope aspect from each cell in DEM using Python?

I am trying to write a python script to calculate the mean aspect upslope from each cell in a DEM. I have the general workflow down, but my final output is restricted to angles between 0 and 90 ...
3
votes
1answer
86 views

What function should I use to assess the degree of elevational change (rocky cliffs etc.) of a DEM?

I have a DEM of my research area and I want to assess how the topography/elevation changes. I am specifically looking to see what areas may be good suitable bat-roosting habitat so I am trying to ...
2
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1answer
150 views

filter / generalize elevation points on the basis of some conditions

I wanted to generalize many elevation points in a rectangular area (about 700 square km). I need to take about 3 points for square km. These points must satisfy some conditions: One of these ...
0
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1answer
3k views

Calculate maximum and minimum elevation for a polygon layer from a DEM [duplicate]

I have a polygon layer and would like to know the min and max elevation within each polygon. My elevation layer is a digital elevation model. I'm not quite sure how to extract that information. I am ...
3
votes
1answer
301 views

Hydro-Enforced/surface constraint DEM Creation using GRASS/QGIS

I am wondering if there is a way to create a hydro-breakline enforced DEM by means of any open source solution? I am able to create a DEM from Lidar data using GRASS, but would like to enforce some ...
5
votes
2answers
572 views

How to extract coordinates & elevations of boundary cells of a 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 find ...
3
votes
1answer
187 views

ArcGIS Raster Symbology - Break contour at 0

In ArcGIS 10, how can I break raster symbology (stretched) at a particular value (i.e. 0). For example, I have a DEM representing both topography and bathymetry and I want a break at the 0 m contour ...
3
votes
1answer
519 views

How to increase resolution of DEM rasters?

Thanks to the fine folks here at the GIS SE, I have managed to batch process a load of ASC files into raster hillshade TIFs. However, while they look fine on screen, when printed they are very ...
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2answers
174 views

Put color for raster data(aspect.tif) on QGIS1.8.0

I create aspect.tif from DEM file. I could put the values(0 to 360)from contrast enhancement. I could set color from color map(freakout or Pseudocolor). In here, the data is shown by only 4 colors. I ...
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0answers
63 views

Is there any accuracy difference between standard DTM editing tools like DT Master and automatic removal of artefacts using ERDAS?

I would like to know whether there is any accuracy difference while editing DTM points using standard photogrammetry software like Inpho DT Master and automatics removal of artefacts in ERDAS imagine. ...
1
vote
1answer
152 views

How to remove terracing from Civil3D GeoTIFF export?

I've received a GeoTIFF DEM that was exported from Civil3D and at every contour there is a distinct terrace created when I process an aspect or slope in QGIS with the GRASS plugins. I've looked ...
3
votes
5answers
2k views

Batch processing DEM rasters in QGIS/GDAL

I am attempting to add relief shading to map using .asc raster files, following this tutorial. It works well, but I have only tried it on single tile of raster data which is 20x20km. I want to ...
1
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2answers
798 views

Import Civil 3D DEM to ArcMap or QGIS

I have some survey data exported from Civil 3D in both dtm and dem formats. I thought the I would be able to use the dem more easily, but I think the format is different from a USGS DEM. Is it ...
2
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0answers
69 views

Arcpy: Counting number of segments where altitude rises or decreases based on DEM?

I have a DEM of Sudety mountains and linear .shp with several hiking paths. I'm trying solve one problem: How to make a script based on input DEM and input line shapes that would count number of ...
8
votes
1answer
455 views

How to generate a DEM from isolines and spot heights?

I have two shape files containing height information of a certain area and I need to create a raster DEM with GRASS using them. file 1 consists of height information in contours (isolines) file 2 ...
3
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4answers
3k views

Open source tool to view DTED and DEM raster-data

I am new to GIS field. Is there any open source GIS tool to view DTED and DEM tiff-files? Update 1 I have some DTED files and DEM files. I want to open and see those files using some open source GIS ...
6
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1answer
811 views

How to calculate te area between contour lines on a DEM with QGIS 1.8?

Does anyone know how to calculate the area in km² for each altitudinal band (between 100 and 200, 200 and 300...) based on a DEM? I added the contour lines with a distance of 100 metres but could not ...
2
votes
1answer
430 views

Orthogonal Height Profile along line (sextante -> v.segment, r.profile?)

While trying to find a way to find "valleys/ridges" within a DEM, I'd like to know if there are tools, plugins or "methods" known or available to automatically generate height profiles along a given ...
5
votes
1answer
168 views

Calc bottomline of valleys

Which way do I calculate bottomlines of valleys or even more preceise: which way do I "find" valleys (for example suggested tectonic faults). Sample below shows a height profile (profile from line) ...
12
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2answers
604 views

PostGIS interpolation / triangulation options

I'm looking for an open source workflow to automate DEM construction. We have a series of sites that fall within a LIDAR dataset. We want to create site specific DEM's for each site, and we're ...