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

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918 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 ...
2
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2answers
194 views

Driver Error : DTM to Raster using GDAL_GRID

I am looking to interpolate a DTM (eventually over 4,000 DTMs) that is in a personal geodatabase format. I would like to do this in as few step as possible, eventually writing a batch script to do ...
3
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1answer
648 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 ...
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0answers
26 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
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1answer
151 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 ...
2
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1answer
501 views

Programmatically download (seamless) NED tiles?

I used to download 1/3 arcsecond elevation geotiffs from extract.cr.usgs.gov using web services. But a few days ago, that stopped working, probably because USGS reorganized their site. I tried ...
21
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4answers
2k 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 ...
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3answers
986 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
5
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2answers
459 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 ...
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2answers
4k 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 ...
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1answer
222 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 ...
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1answer
448 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) ...
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1answer
838 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 ...
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1answer
487 views

Using Latitude and Longitude with SRTM3 DEM file

I am new to working with DEM files but have a need to be able to work with SRTM3 DEM files to calculate elevation given a Lat,lon coordinates. I understand from reading the documentation that the ...
1
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2answers
366 views

How do I intersect DEM and a polyline?

I'm working on Qgis, I need the longitudinal section of a river. Thanks
1
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1answer
405 views

How to calculate an hypsographic curve of a raster trhough a DEM

I am using Arcgis 10.1. I have a MODIS raster from the NSIDC website with a pixel resolution of 500 m and an attribute table with the fields 'VALUE' (as the code of snow, clouds, etc.) and 'COUNT' (as ...
6
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3answers
1k views

Generating TIN from DEM using MacOSX/Unix tools?

I'd like to generate a 3d terrain model moving from a DEM dataset (currently in shp and GeoTIFF format). As far as I understand it, the first step of the better path would be generating a TIN, but I ...
2
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1answer
83 views

Looking for literature on correcting one DEM with another

I am looking for some scientific papers (any language) according how to deal with the correction of one DEM with a other (such as ASTER with SRTM). Any idea? Thanks!
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2answers
1k views

How to compare two DEMs and show their difference?

I want to compare my DEMs (ASTER GDEM2 and SRTM4.1). I know, that the GDEM has some extreme "holes" with totaly wrong elevations (I found 3 of them in my working area). Now I need to know, if there ...
2
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1answer
444 views

How to manage null values in QGIS

I made a merge of several AsterGdem blocks near Egypt and Israel. I have portions of the Dead and Mediterranean Seas. Since near Galilea elevations are below sea level this makes the following problem ...
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0answers
214 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. ...
4
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1answer
222 views

DEM local adjustments - terraforming

I'm looking for software that can perform local adjustments in DEMs with tools similar to paintbrushes used in graphics editing programs but streamlined to respect geomorphology. To give you an idea ...
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2answers
737 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 ...
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4answers
737 views

Does a value in srtm dem file refer to the center or corner of a cell?

I'm working with srtm dem files. They are ascii text files containing a table/grid of elevation values. At the top of the file is some metadata to locate the grid in lat/lon: xllcorner ...
3
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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
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1answer
49 views

What is the method for finding the percentage of common cells among 2 or more DTMs for the same area?

I have a study area and 6 different DTMs for that area from different sources and I would like to know the percentage of pixels with the same value. I suppose I will have to extract some statistic and ...
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1answer
456 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 ...
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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. ...
5
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2answers
816 views

Best Program to use for DEM data?

I need to estimate the elevation at various access points of some rivers in South Carolina. I use the elevation information to calculate the average gradient (feet/mile) between two access points. The ...
3
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4answers
666 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 ...
8
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3answers
15k views

How to extract raster DEM elevations to vector attribute tables in ArcGIS 10?

I have an ArcMap 10 project with multiple layer groups. One layer is a raster DEM, another layer group is a bunch of vector shapefiles (including points, lines and polygons). The client wants all ...
7
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3answers
769 views

Creating raster or vector raster from DEM point file?

i have a point shape of 75.000 elevation points in a regular 5 m grid. We now want to create a polygon grid with the elevation points as "centroids". Unfortunately, all attempts to do so fail: I ...
12
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4answers
602 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 ...
5
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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 ...
3
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1answer
537 views

Correct ASTER with SRTM or Topographic Map

I have a problem with my DEM again. I decided to use ASTER GDEM2 (for different reasons). ASTER GDEM2 have its problems, I know, and I dont want to discuss that again. I have to use it, because SRTM ...
5
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2answers
5k views

How to create a digital elevation map?

I am very new to Quantum GIS, I want to create a digital elevation map a particular region, I would very much appreciate if some one gives me a step by step procedure. Thank you edit by Martin: I ...
3
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2answers
238 views

how to fill voids in ASTER stereo-images for DEM generation?

I'm trying to use a stereo-pair of ASTER images to generate a DEM (in ERDAS Imagine). However, the mountains are rather cloudy and the images can't be used as they are. But the relevant parts (valley ...
11
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1answer
530 views

QGis raster terrain analysis - The curvature filter puzzles me

I am a french Master student at university Grenoble INP, and during my master project I have worked on DEM (raster) terrain analysis. Thus, I have read the source code of several QGis-1.7.4 raster ...
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1answer
3k views

Where to acquire elevation data for UK?

I'm looking for digital elevation data for UK. Does anybody know if there is a good service providing data for free that are of better accuracy than ASTER-DEM that is around 30m and if not what is the ...
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1answer
168 views

srtm30 image: some are grayscale some are black & white

I downloaded these DEM files, http://www.dgadv.com/srtm30/ srtm30 globe. I open the DEM files in Multispec. Some of them are black& white, some are automatically grayscale. How do i get them ...
3
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1answer
680 views

Export SRTM30 Dem file as 3d

i have downloaded some SRTM Dem files here: http://dds.cr.usgs.gov/srtm/version2_1/SRTM30//srtm30 They are from the USGS site. I would like to export them as 3d. I have ran through a few ...
4
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1answer
1k views

How to create a Digital Elevation Model

How to create a DEM starting from layers shapefile "contour lines" and "shares"? which module of GRASS I need to use? thanks for yours responses....
12
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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 ...
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1answer
94 views

How do I retrieve an arc ascii grid file from NED 1/3 second data using python and OWSLib

I have my bounds, and have been able to connect to the server http://imselev.cr.usgs.gov:80/wmsconnector/com.esri.wms.Esrimap/USGS_EDC_Elev_NED_3? in python. What I don't know how to do is send a ...
6
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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 ...
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2answers
208 views

Issue converting DEM in ASCII with LO17 (apparent) projection

I'm a newbie where GIS is concerned, so please don't hesitate to point me to a manual. We've got DEM files without any projection information. One is called 000426_LO17_200M_BD16_25.ORT and contains ...
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5answers
855 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 ...
6
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3answers
1k views

What is a good way to produce wire frame images from DEM?

As part of a project for a wind turbine assessment, I would like to make a wire frame image to compliment my Viewshed / line of sight and Photo montage. I have never created a wire frame image from ...
6
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1answer
5k views

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

Which is better DEM or TIN? What are the benefits/negatives of each?
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2answers
3k views

Viewsheds and Observer Points in ArcGIS Spatial analyst

I am trying to understand the viewshed and observer points tool in spatial analyst. I want to show which areas of land can see a wind turbine, or put another way, from where can the wind turbine be ...