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

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723 views

How do I know the vertical/horizontal units of my DEM? I'm creating a slope using gdaldem

I'm using gdaldem to create a slope map. I can apply a scale. The default is 1. The notes say: Ratio of vertical units to horizontal. If horizontal unit of source DEM is degrees (e.g WGS84 ...
2
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0answers
119 views

Displaying DEM raster in QGIS

Using Raster>Analysis>DEM to display hillshade produces the message "gdaldem.exe had stopped working" so I asked the community. I'm new to QGIS, and I now realise after a little experimentation that I ...
2
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1answer
403 views

How do i convert STDS file to ASCII DEM?

I've downloaded several 7.5 minute DEM files from USGS and they have file names like: 1661629.DEM.SDTS.TAR On MAC these decompress into a folder with serval files having the extension '.DDF'. Is ...
3
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1answer
161 views

How to set waste water gravitational flow direction using DEM automatically?

I have a Geometric Network of Waste Water and I need to set line digitize direction according to the gravitational flow direction using a DEM. I'm trying to avoid flipping manually 1000 Km of ...
2
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3answers
138 views

Working with GB SRTM Digital Elevation Model (DEM) 90m

I have downloaded the freely available DEM file from sharegeo open. I would like to know for a set of points at what elevation they lie. I have imported the DEM file into ArcGIS but it seems strange; ...
2
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1answer
69 views

Profile plot trouble in Grass GIS

I'm new to Grass and GIS environments in general, and I recently faced a problem when trying to get the profile plot from a DTM. When I draw the transect, instead of the plot, I get the following ...
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3answers
453 views

What DEMs does QGIS support? + DEM data sample

I am working on QGIS rasters. I want to know about DEM file formats supported by QGIS. I know that QGIS can read the GDAL supported formats. but what is GDAL supported format ? Does QGIS support the ...
3
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1answer
129 views

DEM sources for arctic regions

Are there any 90m DEMs out there for regions north of where the SRTM dataset ends? I looked at ASTER, but it seems to have a lot of unfilled voids, and it's important that the resolution matches the ...
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0answers
156 views

How to merge raster quadrangle tiles in qgis?

I've downloaded some dem tiles from here http://www.granit.unh.edu/data/search?dset=dem/dem174, which I'd like to merge into a single smooth digital elevation model usinq QGIS. So far I've tried ...
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1answer
79 views

How do I determine the subsidence of land in Manila, Jakarta and Bangkok?

Can I set how these cities have lost elevation using digital elevation models? Is there a digital elevation model which data are updated? Or are there other methods? Thanks.
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572 views

How do I redefine the projection of a DEM?

I have a DEM that was exported from AutoCAD civil 3D 2013 but it's in the wrong projection. I'm using an area specific projection that was not provided as an option in CAD DEM export dialog box. I ...
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1answer
3k views

How can to merge DEMs in ArcGIS for Desktop 10.2?

I'm trying to merge some dems downloaded from USGS. When I used arcgis 9.2 there was an expression to be used in raster calculator to do that. I used it again but unfortunately it doesn't work in ...
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1answer
3k views

Labeling contour lines in ArcMap [duplicate]

Can anybody give me advice on how to label contours as shown in Figure 2 below? I would like to be able to put the label "on" the line, which is easy enough. But I'd also like for the contour line to ...
1
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2answers
370 views

Where can I programmatically download SRTM_V4.1 data?

SRTM v4 is an effort by the folks at CIAT-CSI to scrub, polish, and remove gaps in the raw SRTM data released by NASA (SRTM 3). One userfriendly interface : http://dwtkns.com/srtm/ provides ...
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0answers
201 views

What is most suitable DEM to delineate watershed (from spot height, ASTER and SRTM)?

I have three DEMs of our country which are spot height DEM, SRTM DEM and ASTER DEM. SRTM has 90m resolution and ASTER has 30m resolution. My supervisor told me to delineate watershed using these ...
2
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0answers
593 views

How to limit a specific area in order to have a topographic 3D map using MatLab?

I am using MatLab, I want to build a topographic 3D map, I am following this guide, I have been doing the steps listed on the section Draping Geoid Heights over Topography, and I do not have any ...
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1answer
64 views

About getting area from DEM below 5000 and below 3000 m elevation? [duplicate]

I want to get the area from the DEM which is below 5000 and 3000. Actually I need those two areas for my Regression Model to calculate the discharge. In that case, how can I find out using python. I ...
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0answers
103 views

3D Polyline by Slope on Surface

I wish to project (continue/extend/whatever) a polyline upslope following a specified gradient along a DEM surface. Is there any way of doing this?
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1answer
44 views

How to export Std Dev from Raster Dataset of DEM to classify current extent and execute Contour Tool with Python?

I want to create Countour Lines for a DEM which are based on a "STD dev" classificaion. My problem is that the "Std dev" is exported in an unknown type instead of a String. So the classifacation for ...
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2answers
511 views

Can I prevent QGIS raster clipper from changing output cell/pixel size?

I have performed a DEM extraction using the clipper tool in QGIS 1.9.0 Master, using a mask layer, the original resolution of the DEM is 20x20 but in the resultant DEM the new resolution is ...
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1answer
355 views

Overland flow modeling Help

I would like to determine the surface flow network, this based on the spatial analysis of DEM data and the creation of separate layers for surface ponds and preferential surface flow pathways. More ...
2
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1answer
499 views

How to find area of Digital Elevation Model above/below a reference plane?

I am using ArcGIS10. I need to find the out the area which is below 5000 and above 5000 from the Digital Elevation Model which is available to me. How can I find out this ? My DEM ranges from 8848 to ...
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1answer
81 views

rooftop modeling

I´m trying to model building rooftops based on a LiDAR dataset. I've already interpolated using Delaunay's triangulation a DEM with 1m resolution. Due to LiDAR data is not accurate in building edges, ...
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2answers
2k 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
304 views

Volume of Land Below Sea Level

How could one use a GIS (or other appropriate system) to calculate the change in mean ocean levels across the world if all the land below sea level were flooded (Death Valley, Caspian Depression, Afar ...
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2answers
153 views

How to create a single contour defining the boundary between sea and land

Hello! I am still learning so forgive me if my question is very simple... I am trying to create a map with ArcGIS. The area I am working on is a seasite and I found that in some parts the cells appear ...
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0answers
216 views

Error Message Orthorectifying ASTER Imagery in ArcMap 10 with DEM

I am trying to orthorectify ASTER imagery (VNIR, 15m resolution) in ArcMap using an ASTER DEM that I have downloaded from the GDEM website. The area is in the Andes, there are very high elevation ...
4
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2answers
158 views

How to (vertically) register a DEM to GPS readings?

I don't know if what I ask is possible or not but let's try... I have two datasets: a DEM as a point cloud in a relative coordinate system, constructed with 3D algorithm structure-from-motion. 20 ...
4
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1answer
1k views

Zonal Statistics for Polygons with R

I'd like to do zonal statistics / terrain analysis with polygon overlays - I achieved to get min / max like so: library(raster) library(rgdal) alt <- getData('alt', country = "AT") gadm <- ...
0
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1answer
59 views

Qgis nightly build - DEM error

I installed Qgis 1.8 several months ago. It's been working like a charm. Earlier today, I decided to check out the latest nightly build. Installed GDAL 1.10 (already had 1.9 installed) and SQLite ...
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4answers
1k views

How to create a point cloud from DEM?

Please forgive my ignorance if I am asking a totally irrelevant question, I am still a GIS newbie. I looked in Google and found a lot of links as of how to convert point clouds to DEMs. I am trying ...
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0answers
158 views

QGIS 1.8.0-Lisboa error message when converting DEM to Contours

I am trying to convert a small DEM (1 megabyte) into contours. When I go to - Extraction - Contour- and run it I get the following message: "ERROR 1: CPLRealloc(): Out of memory allocating 416 ...
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1answer
281 views

Does NASA DEM contain objects?

Following an answer to my previous question I am planning to work with NASA ASTER GDEM global dataset. I am trying to download it according to instructions given here for a couple of days now. ...
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2answers
1k views

How to extract elevation data from binary .ADF elevation format at given coordinates?

I have a high resolution digital elevation model available. The ground resolution is 1 meter and the file format is adf which is some binary ESRI grid raster format. I have a script the outputs x/y- ...
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2answers
259 views

How to intersect shape files with elevation models?

I have a high resolution digital elevation model (DEM) and a line shape file displaying a bycicle track. The DEM has 1 meter resolution. The line shape is something like 25 km long. What I need is a ...
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1answer
496 views

How to run a shortest path analysis for DEM-derived streams and pour points?

I have a .shp for streams and another for pour points. Those features were extracted from a DEM by using the Hydrology package from the Spatial Analyst Tools of ArcGIS 10. I want to know the distance ...
0
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1answer
4k views

Creating Digital Elevation Model (DEM) from Google Earth Image? [duplicate]

I am very new to GIS and given the task to create DEM's of agricultural area. I have studied the advantages of DEM in agriculture now i just want to know how i should start to develop the DEM's ? How ...
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2answers
526 views

How to find upstream and downstream villages along a river

I have a DEM extract of river and village centroid. How do i create an attribute table that shows which village is upstream of other or downstream to another. Can someone guide me the correct tools in ...
2
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1answer
135 views

Should only a “bare-earth” DEM be used when calculating CTI?

I have 50-meter DTM and 20-meter DSM data available to choose from to use for calculating a compound topographic index (CTI). While the 20-meter resolution is more attractive, logic tells me that when ...
3
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3answers
796 views

Advantage of Digital Elevation Model (DEM) in Agriculture?

I have given the task to create Digital Elevation Model (DEM)'s of an agricultural area. I am programmer with Computer Science background and very new to GIS can anyone explain what is advantage of ...
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0answers
147 views

DEM data - Central Europe - noise in heights

I have downloaded DEM data from this page: http://www.viewfinderpanoramas.org/dem3.html. I have written simple program in C++ that takes "bricks" and build resulting height map. Hovewer, I have ...
13
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1answer
560 views

Creating nanoscale DEM with GDAL

A bit of a strange question perhaps, but let me give you a breif explanation of the background before my actual questions: Atomic force microscopy (AFM) is a method that, in short (and to my limited ...
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0answers
551 views

Manually edit cell value in DEM in Arcmap10?

Is there any chance that I could manually pick a group of cell in DEM, then edit the value of them in Arcmap 10? I know about the Aris Grid Editor for Arcmap but it requires licence and it's too ...
2
votes
2answers
445 views

A library/software to create DEM from a topographic map

In one of my projects I need to digitize video clips showing some natural landscape. Specifically I need to know distances between different areas and elevation levels. I have a topographic map of ...
0
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1answer
146 views

How to select a subset of a DEM in ArcScene?

I'm using ArcGIS 10.0 and trying to open a digital elevation model in ArcScene. I'm working on a project and got the DEM data from official sources which is quite huge. The resolution of the DEM is 1 ...
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2answers
2k views

Colouring areas between (vector) contours?

Is it possible to colour areas between (vector) contours without making it a DEM first? Joshdoe seems to have done so in Create filled contour map with GRASS but does not say how.
3
votes
3answers
2k 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
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1answer
214 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 ...
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1answer
121 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 ...
4
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2answers
6k 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, ...