Questions tagged [dem]

For questions about Digital Elevation Models (DEM), Digital Terrain Models (DTM) and Digital Surface Models (DSM)

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3answers
9k views

Where is it Possible to Find DTED0 Set?

As I understand, DTED0 should be available for free. Yet, I am not able to find any download link. Everything that Google search brings up (eg. http://geoengine.nima.mil) is dead and not working.
2
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1answer
2k views

Reprojecting a raster DEM from meters to feet using QGIS?

Is there a tool in QGIS that does the same as reprojecting a raster DEM from meters to feet as in ArcGIS's 3D Analyst > Raster Math > Times ?
3
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2answers
2k views

Clipping polygon layer according to DEM elevation using QGIS?

I have a polygon layer on top of a DEM. Is there a way to clip the polygon layer according to elevation, ie the clipped result being only those areas of the polygon layer between x and y altitude? ...
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3answers
2k views

Import DEM into PostGIS for QGIS

I'm a complete GIS newbie so sorry if I'm using the wrong terminology in searching for a solution to this... I'm trying to import a DEM into PostGIS and display it in QGIS. The data is from the EU-DEM ...
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0answers
99 views

Using GeoBrain WCS4DEM in QGIS?

I added the GeoBrain WCS server to the server list: http://geobrain.laits.gmu.edu/cgi-bin/gbwcs-dem?version=1.0.0& I connect to the server and get a list of layers. I select the first one listed -...
0
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1answer
769 views

Hillshade is block grey in ArcGIS Desktop?

I am trying to create a hillshade on my DEM because I need to be able to distinguish features which I can't do in its current state (see picture). However, when I add the hillshade, it adds a block ...
5
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2answers
806 views

How to query DEM elevation values in a web application based on cursor/click point location?

I work for a city government that has LiDAR derived DEM rasters which we would like to make accessible to other departments in the city. The problem is that many departments don't have anyone with ...
0
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1answer
922 views

Importing DEM in ASCII format into ArcMap and Projecting it? [closed]

I have been trying to import an ascii grid file into ArcMap. However, I am battling to project the data. Can anyone assist? I've tried defining the projection but to no avail. The data should be ...
3
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4answers
7k views

How to clean up contours?

I have .dxf file with contour lines representing elevation. But this contours are too "ugly" and elevation model looks just bad. As you can see on image, contours are not continuous... Is there any ...
2
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1answer
155 views

Combining several rasters before r.surf.contour?

I have been trying to generate an elevation model from contour lines using first v.to.rast.attr and then r.surf.contour. Generally, it works pretty well, execpt for one issue. My data contains a lot ...
3
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1answer
10k views

Is there a way to convert GeoTIFF to DEM?

Simple enough question. The NASA Aster data comes in GeoTIFF format, but the tool I'm using (Sketchup) only accepts DEM. Is there a way to convert? I did a lot of searching, and only found the ...
2
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1answer
193 views

Make a ground mask raster with the Greater Than tool

I'm trying to see if I can replicate the Esri solar suitability site example from this article. I fail on the creation of the binary ground raster. I have made a Bare Earth raster from LiDAR ground ...
3
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1answer
925 views

Add Z and M values to stream network produced from DEM

I created a stream network from an existing DEM. My ultimate project goal is to be able to select a river from my stream network and use the 3D analyst to generate stream profile (Elevation by ...
0
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1answer
592 views

gdalbuildvrt error when mosaicking SRTM data with different NoData values?

I'm attempting to mosaic together 9 SRTM tiles downloaded from CGIAR to produce a DEM of Borneo. I'm using: gdalbuildvrt Borneo.vrt BorneoSRTM/*.tif where BorneoSRTM contains the 9 tif files to be ...
3
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1answer
352 views

Very high resolution stereo-imagery

I'm looking for very high resolution stereo imagery to perform a DEM extraction. The only place I can find sample data is http://www.digitalglobe.com/product-samples but the form does not work for me. ...
4
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1answer
10k views

Removing pixel values below 0 in Digital Elevation Model in ArcGIS for Desktop?

I made a DEM layer from a .las file (LiDAR). How can I remove the black area which contains negative values? Is it possible to set these values equal zero or null?
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3answers
2k views

Account for bridge overpasses in a ground DEM to allow for water flow under the overpass

I have a bare earth DEM made from lidar data (A). It works well and has passed all accuracy tests. It is used in storm surge models. The problem we are having is on underpasses. I need to allow water ...
0
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1answer
3k views

QGIS 2.2: GDAL Grid (Interpolation) Error

As much as i understand Raster -> Analysis -> Raster (Interpolation) can provide me with a terrain file out of a shape file with a Z coordinate. I select the input and output file and a Z field. It ...
3
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1answer
3k views

How to get Drainage Divide and Streams from DTM

Does anyone know how you can get a map like this attached, having the digital terrain model? I'm sorry, but I do not know what is the exact technical term in English for them. I hope you understand ...
1
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1answer
2k views

Find minimum elevation along a polyline and return xy or point?

Using ArcGIS 10.1 and Python IDLE 2.7.2... I'm trying to find the minimum value of a polyline with a raster layer and turn that LOCATION into a point. I put everything together in model builder, but ...
4
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2answers
2k views

Interpolate Temperature Using DEM

I want to "co-interpolate" temperature with DEM. I have SRTM 90m aggregated to 1km and I want to "co-interpolate" my DEM with points with temperature data. How do I do this? I am using ArcGIS 10.
0
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1answer
187 views

Splitting DEM at certain elevation?

I have a DEM that includes bathymetry and terrain elevation and I would like to split it at the coastline. Ideally, I would end up with one tif that's land and one tif that's bathymetry. I have ...
2
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1answer
463 views

How to apply Log Transform to Flow Accumulation?

I have run a flow accumulation for a DEM that I'm working with. I'm trying to apply a log transform because I've heard it could give a better visual representation. How would I go about doing this ...
4
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1answer
3k views

How to give elevation information to a polygon feature class using existing TIN file ? (geological mapping)

I'm an ArcGIS 10.1 user. My issue: I have a printed form of a map which depicts geological bodies being surface rock occurence. Additionaly, there are elevation contour lines. I digitized the map by ...
4
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1answer
408 views

Elevation maps from point clouds: TPS vs. other methods?

In the reply to another question, @thehealingprocess refers to "...a comparison of interpolation methods for interpolating elevation maps from LiDAR clouds, and in almost all scenarios thin plate ...
8
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1answer
2k views

When computing flow direction, the D8 algorithm is used - are there major differences if others are used?

I am a student working with Hydrological models. Within these models we can route water across a DEM (within a delineated watershed or just within an un-delineated DEM) using many different flow ...
2
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1answer
2k views

QGIS DEM (Terrain models) Mode Slope creates wrong data [duplicate]

I have a DEM raster file downloaded from the USGS site. The file can be downloaded here. I am trying to create a slope raster in percent with the DEM tool in QGIS. The GDAL command is the following: ...
3
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2answers
1k views

How to create 3D water depth with ArcScene?

I was trying to visualize flood depth in 3D using ArcScene. What I had for this purposes are: high-resolution DTM of the valley orthophoto and Raster with flood depth information. I have draped the ...
1
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1answer
6k views

Fill sinks error in arcHydro [closed]

I am working on a project that is modeling runoff at a county level. The DEM used is lidar derived and has a 5 ft resolution. The general workflow I am flowing is Sink evaluation Sink Selection (to ...
1
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3answers
872 views

Calculate Number Of Pixels Visible From Pixel

I am looking for a way in which to take an input DEM and create an output raster whose pixel's value is the count of pixels "visible" from that location. I use ArcGIS with Spatial Analyst, but also ...
2
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2answers
189 views

What are the ways we can control the quality of a DTM?

I imagine that for DTM obtained from Stereoscopic procedures or interpolation from a set of topographic points a comparaison with the original data can help, but what for DTM obtained from Remote ...
2
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1answer
2k views

Where can I obtain 3D data for Singapore?

I am looking for providers of 3D maps/models of Singapore. This might be either from photogrammetry/laser techniques or based on a DEM + building footprints/landuse with a height attribute. Is any ...
1
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0answers
98 views

Defining uphill side of roads using ArcGIS Desktop? [closed]

I have a big raster of a mountainous region, and I need to extract the uphill side of roads, from the road to the peaks of the mountains. For a road, I know the uphill side changes to become the ...
0
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1answer
532 views

How determine data type of points in geotiff DTM?

I have some DTMs in geotiff files. I need to read them in C# and I've decided to use libtiff for that purpose. After some investigations, I've found that there are tiled tiffs, so I use ReadTile ...
1
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1answer
656 views

How to use ArcMap for HydroPower Potential

I am trying to determine the sites for small hydropower. I have a elevation dem, rainfall data, Curve number data (from soil and landuse shapefiles). I have already used the DEM to fill sinks, find ...
3
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2answers
916 views

Merging DEMs of different grid size

I'm trying to merge two grids with different cell size. One has a cell size of 10m and the other 50m. The 10m one covers a subarea of the 50m one. I know that the most accurate one is the 10m one and ...
0
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1answer
264 views

DEM difference looks like a hillshade

I wanted to find the elevation difference between 2 DEMs. When I got the data, I had to georef one image and had to aggregated it too because their cell values do not match. I also tried to resample ...
5
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4answers
5k views

Creating DSM and DTM from a LAS using a freeware solution

Is it possible to export a surface and terrain model files from an aerial, LiDAR point cloud (LAS) set? I am using SAGA GIS for very basic operations, but I couldn't find this option (and I have a ...
1
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1answer
1k views

Adjusting Z Units on DEM

I am learning how to use Arc Hydro and attempting to change the Z Units because I get a warning message saying the Spatial Reference Doesn't Match. The DEM was in Meters, and I adjusted the Z Unit ...
11
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9answers
26k views

Open source tool to convert a DEM to a 3D model

I would like to convert a DEM (Digitial Elevation Model) file (e.g. from SRTM) into a 3D model that I can then edit with regular 3D modeling tools (e.g. Meshlab/Blender/etc.). However I'm using Ubuntu ...
3
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2answers
3k views

Create Contours From a DEM without 3D or Spatial Analyst

I'm wondering if there is a way to create contours from a DEM using ArcGIS without 3D or Spatial Analyst Extensions. I know that there are a few questions out there pertaining to this (How to create ...
3
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2answers
17k views

Producing CSV file from .tif file with elevation data [duplicate]

I have a .tif file that contains all the elevation of a country. How can I convert that to a CSV file that contains x,y,z values where x and y are the latitude longitude respectively and the z ...
8
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2answers
7k views

How do you identify ridges on an elevation raster?

I was wondering whether anyone might be able to tell me in layman's terms how to extract or differentiate between ridges and hilltops from 10m elevation data using ArcGIS 10.1?
2
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2answers
923 views

Terrain Accessibility map using GIS (ArcGIS or QGIS)

I need to make an accessibility map showing the walking distance based on the terrain and availability of road networks, could anyone point me in the right direction where i could learn to do so. ...
7
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4answers
3k views

What are the most efficient Geographic Weighted Regression packages?

What are the most memory efficient open source packages for calculating a geographically weighted regression (GWR)? I am in a situation where I need to do a geographically weighted regression on a ...
1
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2answers
2k views

DEM/Raster Peak and Valley identification and/or elimination (non-generalization)

Is there is a tool or process that can identify and/or eliminate obvious peaks and valleys in a DEM? I have looked into smoothing at What raster smoothing/generalization tools are available? but I ...
8
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2answers
7k views

DEM Elevation Units

I'm fairly new to the GIS world, and have a quick question. I'm currently using ArcGIS 10.1. I do not know much about rasters, so does transforming a DEM from one projection to another automatically ...
23
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1answer
32k views

Choosing IDW vs Kriging Interpolation for DEM creation?

I'm trying to create a DEM using point data spaced very regularly about 10m apart. The area I am interpolating is an educational facility with many flat parking lots and football fields but still has ...
1
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1answer
3k views

Creating Cost Surface Raster for Least Cost Path Analysis?

I have a DEM raster and would like to carry out a cost path analysis. Among other factors such as slope, proximity rivers etc. I would also like to take elevation into consideration. According to ...
0
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1answer
216 views

Generate subcatchment starting from a DTM [duplicate]

I would like to know if there is a plug-in in Quantum GIS, which can help me to generate subcatchments starting from a DTM.

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