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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1answer
759 views

Problem merging two rasters in Qgis

I have two rasters in Geotiff, same CRS. I tried to merge them and I have this error code ERROR 4: `C:/Anita_Tepoztln/Rasters/e142.tif' does not exist in the file system, and is not recognised as a ...
1
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1answer
110 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 ...
2
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0answers
411 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 ...
2
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1answer
342 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 ...
0
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1answer
58 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 ...
9
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2answers
827 views

Floodplain generation given river section polylines, flood level elevation points and a DEM of the land surface

I am looking to generate flood plain polygons to represent 20 and 100 year flood zones, in the most accurate and efficient way possible, given the following datasets: 1) River cross section polylines ...
0
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0answers
88 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?
13
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1answer
498 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 ...
37
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7answers
40k views

What is the difference between DEM, DSM and DTM?

I am listing some of the acronyms used in our work and had to stop to think about whether to list these together or separately. In some circles they are synonymous, in others they have distinct ...
1
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1answer
259 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 ...
1
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1answer
73 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, ...
4
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2answers
6k views

Viewing .las format LIDAR data in QGIS?

Is there an easy path to visualizing this LIDAR data? I have QGIS, and some USGS LIDAR data in (.las) format downloaded from http://lidar.cr.usgs.gov/ . This means I have both the (.las) and ...
1
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1answer
203 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 ...
4
votes
2answers
133 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 ...
1
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0answers
158 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 ...
6
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4answers
2k views

Definitive source for downloading DEM data

USGS has been moving towards serving data through The National Map Viewer. They have several WMServices through their website that serve elevation data to the public (hillshade & DEM). The ...
4
votes
1answer
714 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 <- ...
4
votes
1answer
434 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 ...
1
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0answers
221 views

tools from Geospatial Modelling Environment in ArcMap model [closed]

How to extract raster DEM elevations to vector attribute tables in ArcGIS 10? Can GME tools be used in model for publishing a tool on web? I want to use it in integration with other tools in ArcMap. ...
0
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1answer
57 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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2answers
406 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 ...
0
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0answers
123 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
votes
1answer
226 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
207 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 ...
0
votes
1answer
2k 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 ...
2
votes
1answer
113 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
630 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 ...
2
votes
2answers
367 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 ...
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0answers
125 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 ...
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0answers
290 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 ...
4
votes
2answers
250 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 ...
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
votes
1answer
155 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 ...
6
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1answer
13k views

How to calculate an elevation profile for a polyline in arcgis 10 with spatial analyst/3D analyst?

My elevation data is a floating point tif. I have a road for which I need to calculate the elevation profile, but I can´t see the tools to do this. Can I do this with ArcGIS? yours, Rob
3
votes
2answers
266 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 ...
0
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0answers
170 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 ...
8
votes
2answers
1k views

Extract the area of a DEM above where 60% of the region lies?

I have a DEM of a mountainous region. I'd like to extract the areas of the DEM above which 60% of the total DEM area lies. So, essentially I'd like to extract the areas representing upper portions of ...
1
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1answer
3k 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 ...
3
votes
1answer
183 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 ...
6
votes
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 ...
3
votes
1answer
494 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 ...
5
votes
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 ...
0
votes
1answer
452 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 ...
5
votes
2answers
486 views

Problem Visualizing 3D Terrain Model - USGS DEM

I recently downloaded a GeoTIFF 1 arc second from the USGS National Map Viewer. I added the raster to ArcScene and attempted to visualize the data in 3D. I set the Base Height to Floating on a ...
3
votes
1answer
153 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 ...
3
votes
1answer
511 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 ...
0
votes
0answers
122 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 ...
2
votes
1answer
349 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 ...
0
votes
1answer
112 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 ...
3
votes
2answers
312 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 ...