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

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2
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2answers
156 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
85 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
127 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 ...
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0answers
46 views

ASTER DEM LPS problem

I tried to generate DEM from stereo ASTER image (AST_L1A) using Leica Photogrammetry Suit 2011 version. For this purpose, I used orbital pushbroom ASTER geometric model for block creation. But when I ...
2
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1answer
95 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 ...
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3answers
88 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; ...
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0answers
67 views

How to identify DSM anomaly using Erdas Imagine

I am having IFSAR DSM. I want to detect anomaly (both Spikes and depressions) to fix in the process of DTM editing. Since the file is too large I chose automation for the process of detection. I tried ...
2
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1answer
55 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
188 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
74 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 ...
1
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1answer
93 views

Layers not lining up

I have three layers I need to try match up at the borders. This is not a projection problem, all layers are projected to Albers NAD83. The base layer (Green) is 30m DEM, with a US boundaries layer on ...
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0answers
66 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
59 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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0answers
159 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 ...
0
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1answer
309 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 ...
5
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1answer
527 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
127 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
102 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 ...
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0answers
179 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
53 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
62 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?
1
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1answer
36 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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1answer
140 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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0answers
58 views

resample (data management) tool in Arcgis produces blank output

I have SRTM DEM 3" dataset for Kuwait. I want to resample it to the same resolution as another raster. This raster has a cell size of 3.4m. The resample tool completes without error. The output, ...
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1answer
144 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
168 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
59 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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17 views

update or edit dem raster [duplicate]

if I have dem with some gaps and I want to update my first dem by new dems cover gaps and I want to learn about con in RasterCalculator I work in arcgis10 thanks
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2answers
640 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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0answers
52 views

Adding elevation property to raster cells

I am trying to add elevation to raster cells. I have a land use raster map, and a DEM. And I'm at a loss to figure out how to combine them. Is it even possible to add "attribute" data like this to ...
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1answer
121 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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0answers
90 views

Is there a public FTP server hosting the NED?

I'm having a ton of trouble getting the data I need from the USGS. I have taken a look at the 10m DEM quad index and know exactly which quads I need, but cannot find a source to download them from. ...
4
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2answers
97 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
99 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
120 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
252 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
54 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 ...
2
votes
4answers
270 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
96 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 ...
3
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1answer
147 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. ...
0
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2answers
452 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
162 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
208 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
935 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
231 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
votes
1answer
79 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 ...
2
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3answers
376 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
95 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
378 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
95 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 ...