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

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3
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2answers
439 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 ...
6
votes
2answers
943 views

FOSS method to split raster into smaller chunks

I have a raster (USGS DEM actually) and I need to split it up into smaller chunks like the image below shows. That was accomplished in ArcGIS 10.0 using the Split Raster tool. I would like a FOSS ...
2
votes
2answers
77 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
votes
0answers
56 views

Define uphill side of roads and buildings

I have a big raster of a mountain region and I need to extract the uphill side of roads and buildings, from these elements to the pick of mountains. For a road I know the uphill side changes in ...
16
votes
5answers
10k views

Is it possible to make a DEM from contours in QGIS?

Is it possible to make a DEM from contours in QGIS? I have a shp file (contours) and their heights, can I use QGIS for produce a DEM without using GRASS? I find this creating a dem from contours but ...
0
votes
1answer
103 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 ...
4
votes
2answers
581 views

Focal statistics to calculate saddle points from DEM

I have a conundrum with Focal Statistics and kernel files. I am been trying to identify saddle points in DEMs. I am attempting to rewrite this (thanks whuber) in a python script for 10.1. I have ...
0
votes
1answer
57 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 ...
0
votes
0answers
196 views

converting vectors to raster (burning streams)

I converted my stream vector to a raster file (using polyline to raster conversion tool). I anticipated that I would get a No Data row in the raster file attribute table, so that I could use a ...
0
votes
0answers
64 views

r.shaded.relief plugin on a DEM layer

I loaded a raster digital elevation map from the DEM explorer website. I defined the projection and created a mapset. I then loaded the raster file into GRASS with the r.in.gdal plugin to create a DEM ...
0
votes
0answers
17 views

Adding a Z Unit [duplicate]

I'm struggling with the Z Unit conversion of some data. Both the NHD data and my DEM are in a GCS with Decimal Degrees. These data sets project perfectly on the fly, but after I adjust the Z Unit of ...
1
vote
1answer
132 views

Adjusting Z Units on a DEM

I am learning how to use ArcHydro 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 to ...
4
votes
2answers
1k 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? Any advice would be ...
7
votes
7answers
4k 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 ...
2
votes
2answers
471 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 ...
2
votes
2answers
333 views

How to produce a CSV file from .tif file with elevation data? [duplicate]

just want to ask, 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 ...
5
votes
2answers
366 views

How to de-noise a DSM

I have created a DEM, DSM, and nDSM from a LiDAR Point Cloud using SAGA-GIS. I extracted the appropriate returns from the point cloud, then converted to grid, and then closed gaps to fill in any ...
5
votes
2answers
6k 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
votes
2answers
1k views

1'' DHM: Hillshade is too rough - how to “generalize”?

I got this hillshade from my DHM (I used the hillshade-module from qgis). For my purpose there is too much relief detail (roughness). How can I get rid of this in QGIS or GRASS? Thanks! Martin
1
vote
1answer
485 views

How to create a profile with profile points at discrete altitude intervalls, e.g. each 10 m

In both SAGA and QGIS theres a profile-from-line-function that does a nice job of creating profiles. But there's no way to control the altitude spacing. Any ideas for workflows that would allow me ...
1
vote
2answers
2k views

How to use SRTM DEM files for shaded relief in ArcMap?

I would like to create a nice shaded relief for France using SRTM3 data. Most of the threads on the subject are from awhile ago, when ArcMap was not able to import these without changing the file ...
1
vote
2answers
971 views

Cropping Geotiff with gdalwarp

I downloaded a geotiff from the recently published 25m-DEM of the European Union (see: http://courses.neteler.org/eu-dem-new-digital-surface-model-at-25m/). One tile has about 5GB so I would like to ...
1
vote
2answers
279 views

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

I am an curious 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 but I am interested in keeping the original sharpness ...
8
votes
2answers
1k views

DEM Elevation Units

I'm fairly new to the GIS world, and have a quick question. I'm currently using 10.1. I do not know much about rasters, so does transforming a DEM from one projection to another automatically convert ...
8
votes
1answer
2k views

When to use 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 ...
0
votes
0answers
126 views

Estimating sunlight hours from slope, aspect, and latitude

I'd like to estimate annual sun hours (or insolation, or solar radiation) for 4 points, 1 each on the four sides of the summit of a hypothetical flat-sided mountain. I have slope and aspect for each ...
1
vote
1answer
958 views

How to Create 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 ...
3
votes
1answer
846 views

How to perform a Cost Path analysis in ArcGIS 10.1?

Is it possible to model the easiest pathway through a landscape between many points (rather than just two)? I want to carry out a cost-path analysis, I would like to display the easiest pathways ...
0
votes
1answer
49 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. Thank you very much!!!
3
votes
1answer
290 views

Create DEM from cartosat stereo pairs?

I have two carstosat stereo pair images. All i need to do is to extract DEM from those. So, i tried it doing with OSGeo4W. but i didn't succeeded in it. So IS there any other softwares or opensource ...
7
votes
3answers
609 views

How to get the subbasin area of each specified river segment?

I have a DEM file of one district, and I have used those following tools in spatial analyst tools in ArcGIS 10.1 to get files related to the original DEM file: Fill Flow direction Flow accumulation ...
2
votes
1answer
109 views

NASA ASTER DTM - what is its datum? What are the elevations relative to?

I have downloaded some data from http://asterweb.jpl.nasa.gov/gdem.asp I would like to relate the elevations to some coastal data which is estimated to a specific ordnance dataum. Can anyone tell ...
1
vote
1answer
91 views

How to: script convertion from SRTM to 3D printable file?

Given a STRM3.tiff file as input. How to convert this STRM.tiff file into a 3D printable file ? which I may load into most 3D printers' sofwares. My objective is to print some terran, lunar, or ...
0
votes
0answers
72 views

determine the catchment area from dem or hillshade [duplicate]

I want to determine the catchment area of river from hillside. Is there a plugin that I can use in qgis ?
0
votes
0answers
40 views

qgis - slope from DEM - errors due to projection and oversimplified 'z factor' [duplicate]

I'm trying to generate a slope raster from a DEM raster. It seems there is a pretty significant error due to the 'z-factor' option. I'm fairly new to this, but some other posts and responses ...
1
vote
2answers
276 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 ...
0
votes
1answer
63 views

Change slopes derived from DEM

I have a DEM for a region over which I want to simulate an ecological process. I would like to run several simulations for the same region but I want to alter the topography for the simulations. ...
3
votes
1answer
742 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 ...
3
votes
5answers
2k views

Batch processing DEM rasters in QGIS/GDAL

I am attempting to add relief shading to map using .asc raster files, following this tutorial. It works well, but I have only tried it on single tile of raster data which is 20x20km. I want to ...
0
votes
2answers
87 views

Two r.mapcalc calculations return a much bigger raster cell size than the input raster

I tried the following calculations with a GeoTiff sample, having a cell size of 25m: Calculating the togographic exposure (TOPEX) and estimating the mean topographic curvature Both, the resulting ...
1
vote
1answer
544 views

Creating Random Points in ArcGIS 10.1

I would like to create random points across my study area (which is a DEM raster) using the Feature Class> Create Random Points. However, I need to select/copy/move/delete these points and re-arrange ...
1
vote
1answer
400 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
votes
2answers
224 views

How to identify valleys on DEM in ArcGIS 10.1 [closed]

First, What is the best and easiest way to identify valleys in a DEM raster? Second, how do you create a least-cost pathway for each valley in a region based on low angle slope and proximity to ...
2
votes
0answers
118 views

Whats the best way to create bathymetric contour lines?

I have a raster dataset with both Topographic and Bathymetric stored in it. What is the best way to create exact contours of the lake-bed? This becomes tricky when I want to make the contour for depth ...
0
votes
1answer
202 views

Where to obtain LiDAR Data for Romania?

I need LIDAR Data for realizing a urban hydrology study (Romania areas), whence I can get this data? There is a chance to obtain data for this area (Cluj-Napoca city)? I'm PhD student are chances to ...
2
votes
2answers
465 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 ...
4
votes
2answers
143 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 ...
2
votes
1answer
356 views

GTOPO30 Slope analysis in ArcGIS 10.1 [duplicate]

Using surface - slope analysis tool box. All values for the slope calculation are in between 80 and 89. There are no values below 80. What am I doing wrong?
2
votes
1answer
67 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 ...
0
votes
1answer
143 views

calculate least cost pathways for a region and create distance rasters to rivers [duplicate]

How do you calculate all the least cost pathways that exists for a region? I would like the output map to display all routes (and was wondering whether this can be done in one set of operations). I ...