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

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3
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3answers
850 views

Obtain all elevations points from a raster DEM

I need to obtain all elevation grid points from a raster DEM. I see the steps required as: Read in raster DEM (Arc Info Binary Grid format). Create subset area using Points2One (see triangle area ...
3
votes
1answer
104 views

Digital Elevation Model Algorithms

Can anyone suggest best Suitable Algorithm for Digital Elevation Model Generation? Currently I am working on Literature survey of DEM creation so i need to show comparison of 3-4 Algorithmic Methods ...
1
vote
1answer
96 views

Global DEM and country borders

I am trying to split up the world into 2 categories based on elevation (below 2000m and above 2000m) while still including a country identifier. So in the end, I would like to have 2 types of units ...
3
votes
2answers
1k views

How to generate a DEM from a contour Shapefile?

I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
0
votes
0answers
134 views

catchment delineation

I am trying to use qgis to delineate between three sub-sub-catchments. I have contour shape file of 20 meter height. Sub-catchment is about 12 square kilometers area but consist of three ...
3
votes
2answers
203 views

Hillshade for 30m NED at continental scale

I'm new to terrain analysis. I have a 30m NED DEM (.tif) for the conterminous US. I would like to generate a nice looking hillshade for the US, but it looks bad - as in pixelated and rough (See ...
4
votes
1answer
211 views

How to calculate the volume of several DEMs to obtain elevation and volume changes?

I am trying to calculate the volume of several DEMs in order to obtain elevation and volume changes. I have pixels of 1x1 each one associated to an elevation. I used several methods but non of them ...
0
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0answers
13 views

can anybody explain how to create a wasp contour map in Q GIS? [duplicate]

can anybody explain how to create contour map,I need to export in .map format.
1
vote
1answer
1k views

No. of Bands in the input Raster

I have downloaded a 7.5 min DEM . Now while I am trying to mosaic them it gives me an error saying "Input and target dataset should have the same number of bands" . How can I figure out the number of ...
4
votes
5answers
634 views

Calculating Runoff / Streams using DEM in ArcGIS

I am just curious about the workflow that many of you use for runoff/stream analysis using a DEM and create a "water network" from the results in ArcGIS 10.1? I know the average rainfall for different ...
0
votes
1answer
127 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
vote
1answer
82 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 ...
6
votes
4answers
342 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) - ...
5
votes
1answer
831 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
votes
3answers
954 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 ...
3
votes
0answers
102 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 ...
2
votes
1answer
262 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
votes
1answer
226 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 ...
1
vote
1answer
969 views

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
votes
1answer
321 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
votes
1answer
119 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 ...
0
votes
0answers
97 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 ...
1
vote
1answer
172 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
votes
1answer
243 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
3answers
361 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
votes
1answer
80 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 ...
1
vote
2answers
1k 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
votes
1answer
272 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
votes
2answers
232 views

What is the best source 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
votes
2answers
195 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 ...
1
vote
2answers
395 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 ...
1
vote
1answer
152 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 ...
1
vote
0answers
203 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.
1
vote
2answers
96 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
votes
0answers
41 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
votes
2answers
369 views

how to retrieve 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 ...
1
vote
2answers
357 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 ...
0
votes
0answers
31 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
248 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 ...
4
votes
2answers
537 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?
1
vote
1answer
345 views

Calculating mean upslope aspect

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
71 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
votes
1answer
124 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
votes
1answer
1k 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
220 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
383 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
132 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
259 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 ...
1
vote
2answers
129 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
45 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. ...