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

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7
votes
5answers
2k views

Is there an online tile-based elevation service?

I am working on an application that requires the elevation at a given lat/long coordinate for lots of closely spaced coordinates along any given irregular path. (The path is a trace of a ...
12
votes
4answers
660 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 ...
12
votes
2answers
622 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 ...
1
vote
1answer
212 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
2answers
995 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
2answers
119 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
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 ...
10
votes
4answers
3k views

Code to calculate elevation profile along line from a DEM

Given a DEM (Digital Elevation Model) say in and a line (x1,y1) --> (x2,y2) (paired coordinates (x,y)), how can one calculate the elevation profile or cross-section projected on that line ? I am ...
0
votes
0answers
42 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
347 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 ...
3
votes
1answer
87 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 ...
6
votes
1answer
6k views

Which is better, DEM or Triangles (TIN/Terrain)

Which is better DEM or TIN? What are the benefits/negatives of each?
0
votes
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
311 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
602 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
555 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 ...
4
votes
5answers
927 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 ...
3
votes
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 ...
2
votes
2answers
528 views

batch create DEM from contour maps (open source)

I have around 100 shapefiles of contours (1m interval) that I need to turn into DEMs; Is there a way to batch create these mde from contour lines? Using open source preferably.
1
vote
2answers
179 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 ...
1
vote
3answers
1k views

How To find the Catchment Area for a Dam?

I have a DEM of my study area, and polyline shapefile of the Dams in that area. I have run the standard Hydrology tools on it( Fill, Flow Direction & Flow Accumulation). I know that you can ...
1
vote
0answers
68 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
2answers
835 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
votes
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 ...
-4
votes
1answer
121 views

QGIS to support hydraulic engineering projects [closed]

What is DTM in hydraulic projects? and what is application area of QGIS ?
2
votes
1answer
488 views

Creating a constant elevation raster with multiple attributes

Is it possible to create a raster with a constant value with multiple attributes? Such as: rowid value count Name 1 630 36000 Forest 2 630 75000 Anthro 3 630 2600 ...
3
votes
1answer
1k views

DEM: How to convert a mosaic dataset to TIN?

I merged several DEMs together in on single DEM with mosaic dataset. Now I wanted to convert this mosaic dataset in Vector with TIN. But when I use the tool (3D Analyst Tool) Raster to TIN comes an ...
2
votes
1answer
440 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
172 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) ...
6
votes
2answers
3k views

How to change DEM's gradient colour?

I'm a newbie about GIS. I'm from Italy and I've got a *.tif file of my region. I've loaded it has raster but I have a question: The dem has a gradient colour magenta. How change this colour to ...
5
votes
1answer
395 views

How do I get the upstream distance to all points in a DEM from a single downstream point?

I want to get the upstream distance to all points in a DEM from a single downstream point. The goal is to create a "downstream distance to a point grid". This then would allow me to create "distance" ...
5
votes
2answers
2k views

Exporting DEM-derived rasters to CSV from QGIS?

I have been able to import into QGIS a set of raster topographic maps and the associated DEM raster maps. It registered the two for me. From there I have calculated the associated slope raster map. ...
9
votes
3answers
3k views

Best method to aggregate 1m DEM mosaic to 10m DEM

I have a mosaic of a 1m LiDar derived DEM. I need to output a subset of the data as a 10m DEM. I am currently using the aggregate tool in ARCGIS 10 to produce a mean value for each new 10m pixel. ...
3
votes
1answer
84 views

Is it possible to create DEMs from ORT format in QGIS?

I recently requested DEMs for my area of interest. The data has however arrived in ORT file format - how do I create DEMs from this data in QGIS? When I open the files in Notepad there are three ...
8
votes
5answers
320 views

How to ensure uniform colour for DEMs?

This is a silly question, but one I've been trying to figure out for a while. I have two Aster DEM tiles, one next to the other. How do I ensure uniform colour for both?
3
votes
2answers
641 views

Can I sell maps produced from ASTER Global DEM V2 data?

I don't quite understand the term-of-use of ASTER Global DEM V2 data: By selecting 'Submit', I agree to the following: -I agree to redistribute the ASTER GDEM only to individuals within my ...
3
votes
1answer
457 views

Where can DEM data for all of British Columbia be found?

Is there a website or server from which a DEM covering all of BC can be downloaded - preferably at 1:50K scale? GeoBase has tiles for 1:50K and 1:250K, but they do not provide it as a mosaic. It's ...
12
votes
2answers
1k views

Is it possible to manually correct a raster DEM (OpenSource)?

Is it possible, to correct a raster DEM by changeing the raster-cell-values manually, like by "painting"? My DEM (ASTER) have one small error where the elevation is about 300m below the actual ...
3
votes
3answers
1k views

Merge DEM and Hillshade to create one file?

I am wondering if I could merge DEM and Hillshade ? What is the pro and cons for that? Thanks
3
votes
1answer
731 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
vote
0answers
28 views

Can I burn stream network into DEM using DEM layer only? [duplicate]

Possible Duplicate: How to ‘burn’ a stream network into a DEM layer in ArcGIS 10? I am doing hydrology modelling and I want to calculate the run-off. In order to do that,the model which I ...
5
votes
1answer
156 views

How do I find location of minimum value within a buffer (around a point)

I have a digital elevation model (DEM) with a point location defined. I want to locate the lowest height values at a set distance from this point. I envisaged creating a buffer around the point ...
21
votes
4answers
3k views

How to calculate terrain Curvature?

I have an elevation raster and I would like to get some basic terrain variables, such as slope, ruggedness, aspect or curvature. The problem is that I don't seem to have the possibility to calculate ...
1
vote
1answer
678 views

Help with technique to create contours from ASTER DEM in Phnom Penh, Cambodia

I have the ASTER version 2 DEM of Cambodia. I want to use it to create 1m contours of Phnom Penh, Cambodia. If anyone has this already please let me know. Now, onto the problems: I am using ArcGIS ...
6
votes
2answers
5k views

Is there a way to clip a raster using a vector polygon without having Spatial Analyst?

I have ArcView 10 and I'm trying to clip a DEM (TIFF) to a wilderness boundary (polygon). I know ArcView won't let me do this without Spatial Analyst, but I don't have $2500. I tried exporting my ...
1
vote
1answer
251 views

arcgis python window VS pywin32

I have problems while using the ZonalHistogram function in Python. It seems to give strange results, while, with the same code run in arcgis' python window everything works fine. I am trying to study ...
4
votes
4answers
755 views

Is there a way to programatically force RGB (3 bands) in a raster with arcpy?

I'd like to include conversion to a 3 band RGB raster in a script to prepare multiple DEMs for image processing. The input files are rasters extracted from a raster mosaic. The manual option is to ...
1
vote
1answer
519 views

Where to acquire free elevation data for Thailand/Bangkok?

I am in the process of writing my thesis on flood hazard preparedness and forecasting in South East Asia, specifically Thailand. My analysis requires a medium resolution (even better, high resolution) ...
2
votes
1answer
1k views

Extraction of DEM from netCDF file into ASCII XYZ format

I need to extract a DEM of a waterbody from a netCDF file so I can ultimately convert the DEM into xyz format. I'm not sure how to go about doing this, and so far, I have tried to create raster layers ...
1
vote
2answers
426 views

How do I intersect DEM and a polyline?

I'm working on Qgis, I need the longitudinal section of a river. Thanks