Digital Elevation Model (DEM), which could be a Digital Terrain Model (DTM) or a Digital Surface Model (DSM).
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0answers
22 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
votes
1answer
106 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 ...
1
vote
1answer
402 views
Help with technique to create contours from ASTER DEM in Phnom Penh, Cambodia
I have the ASTER version 2 DEM of Cambodia. I want to use it to create 1m contours of Phnom Penh, Cambodia. If anyone has this already please let me know. Now, onto the problems:
I am using ArcGIS ...
5
votes
2answers
883 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 ...
6
votes
3answers
441 views
Generating a TIN from a DEM without ArcGIS
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 ...
1
vote
1answer
139 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 ...
2
votes
4answers
299 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 ...
1
vote
1answer
209 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) ...
2
votes
1answer
303 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 ...
2
votes
2answers
2k 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 ...
1
vote
2answers
160 views
How do I intersect DEM and a polyline?
I'm working on Qgis, I need the longitudinal section of a river.
Thanks
1
vote
1answer
252 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 ...
2
votes
2answers
174 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 ...
3
votes
1answer
134 views
Change ellipsoid reference for altitude in a DEM
I have DEM data stored as RGF93 (Lambert-93) for lat/lon and NGF-IGN69 for altitude. I'm trying to change the reference ellipsoid for the elevation data (ultimately to NTF, but WGS84 would be fine to ...
1
vote
1answer
212 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 ...
2
votes
1answer
70 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!
5
votes
2answers
465 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
votes
1answer
272 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
...
0
votes
0answers
108 views
Importing Large Raster Datasets in Global Mapper
I'm having issues importing large amounts of data. I have about 25 gigabytes (2752 files ) that im trying to export as one big hill shade. I did this successfully in ArcGIS but i wasn't happy with the ...
2
votes
0answers
136 views
tools from Geospatial Modelling Environment in ArcMap model
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.
...
3
votes
1answer
140 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 ...
4
votes
4answers
281 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 ...
1
vote
1answer
117 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 ...
4
votes
5answers
3k views
Problems merging DEMs or other raster datasets? Clipping Raster dataset to vector line?
I have two DEMs that I am going create a hillshade from, and ultimately want one hillshade clipped to a county boundary. I am running into a couple problems, though.
When I try to merge the two ...
2
votes
1answer
246 views
Conversion of ASTER GDEM data for CFD Analysis
I need to do a computational fluid dynamics (CFD) analysis of wind over a large area of land. I have obtained the necessary tiles from the ASTER GDEM data set (in .tif format) and was wondering how I ...
2
votes
2answers
2k views
Replacing Raster Values in Ras1 with Ras2
I have two rasters Ras1 and Ras2.
I want to change the Ras1.
In Ras1, there are few areas, lines, points I am interested having nodata cells and wrong data cells.(limited to interested areas only ...
4
votes
2answers
388 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 ...
7
votes
3answers
443 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 ...
4
votes
4answers
728 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
votes
1answer
356 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
votes
2answers
1k 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 ...
1
vote
1answer
79 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 ...
5
votes
2answers
295 views
Seeking commercial web service for LIDAR/DSM data in USA
I apologize for not knowing all the proper terminology to ask this question. I am seeking a commercial service for providing pay-per-use high resolution elevation data in North America. It must come ...
4
votes
1answer
879 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 ...
11
votes
1answer
328 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 ...
0
votes
1answer
1k views
How can I convert SRTM data to DEM or DTED?
i am working on a project which is not commercial and i need some digital elevation data for visualization. in net i have found a link and i have downloaded .asc data from following link..
SRTM Data ...
2
votes
1answer
405 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 ...
2
votes
1answer
546 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....
8
votes
4answers
2k views
How to 'burn' a stream network into a DEM layer in ArcGIS 10?
I am working on a DEM that in an area where there is little relief. I would like to 'burn' the river network into the DEM so I can calculate flow accumulation and flow length accurately. I am using ...
1
vote
2answers
464 views
SAGA GIS: How to load an .hgt file?
I want to display and work with the data from http://dds.cr.usgs.gov/srtm/version1/Eurasia/
in SAGA-GIS but am having difficulties knowing which module I should use to load the data.
As far as I know ...
6
votes
3answers
538 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 ...
12
votes
4answers
2k views
What is the best colour-ramp to use for elevation?
This is maybe rather subjective as it concerns style, but I would like to have a few decent colour ramps for my DEM when it is layed over my hill-shading.
I have created the Swiss hillshade model as ...
1
vote
1answer
140 views
How to convert accuracy of DEM from 5 decimal places to 2
I had a csv dataset comprising of regular points containing elevation "z-values". I interpolated this using ESRI´s spatial analyst using the IDW method to produce a continuous raster surface. I set ...
2
votes
2answers
474 views
1'' DHM: Hillshade is too rough - how to “generalize”?
I got that hillshade from my DHM (I used the hillshade-module from qgis). For my purpose there a too much relief details (roughness). How can I get rid of them in QGIS or GRASS?
Thanks!
Martin
4
votes
2answers
2k views
Correct way to create a DEM from point data in csv files
I know this might seem a somewhat general question, but I have to start somewhere.
I have a lot of csv files which contain point data containing height, aspect and slope measurements at a resolution ...
1
vote
1answer
432 views
Why does QGIS Profile from Line tool give me the same value for every point?
I'm trying to make an elevation profile with QGIS's Profile from Line plugin. But when I do, the resulting points all have the same value: -32,767. I'd like to know what I'm doing wrong.
My elevation ...
2
votes
0answers
313 views
GDAL tiling DTED (dt2) dataset as gdal2tiles for 3D Maps
i am searching some webgl technologies to create 3d map with digital elevation data. for web tech. i have found ReadyMap SDK to create 3d map from TMS...
in ReadyMap for elevation data it uses sth ...
2
votes
2answers
123 views
Finding Two locations with a conditional search on DEM
I want to find two locations H difference in elevation between two locations on a DEM.
Ex: point A and B are my output after search on DEM. conditions are (1)buffer R distance around point A and (2) ...
2
votes
0answers
314 views
How to calculate Solar Radiation falling on vertical surfaces using DEMs and ArcGIS?
I am using ArcGIS10 Area Solar Radiation tool to calculate irradiation on horizontal surfaces (building roofs) but need to do the same for vertical surfaces (building facades). Any ideas on how to do ...
0
votes
0answers
152 views
slope and mosaic datasets
I was wondering if anyone has had any experience with combining multiple DEM’s into a mosaic dataset. I am working with several DEM’s and need to convert them to slope. I’m having an issue with ...
