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

learn more… | top users | synonyms (1)

2
votes
1answer
69 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 ...
7
votes
3answers
245 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 ...
0
votes
0answers
39 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 ...
0
votes
0answers
70 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 ?
1
vote
1answer
70 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
39 views

How to generate GML by extracting heights from DEM?

I am trying to generate GML using satellite images for geometries of various objects, and I propose to use DEM of the corresponding area in order to extract heights. I already have a piece of ...
0
votes
1answer
49 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. ...
1
vote
1answer
288 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 ...
0
votes
2answers
60 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
0answers
73 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
93 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 ...
0
votes
2answers
123 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 ...
1
vote
2answers
361 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 ...
2
votes
1answer
156 views

qgis2 slope analysis from NED data gives crazy histogram

I'm attempting a simple slope analysis in QGIS2 using the plugin at Raster -> Terrain Analysis -> Slope. The slope output layer has a very strange histogram, basically spikes at 0 and at 89.9098 with ...
1
vote
2answers
183 views

How to calculate peaks in a DEM

How could I extract all peaks from a DEM (large mountainous area)? Peak means something like: a pixel which is sourrounded by other pixels with smaler elevation numbers in a area arround the ...
5
votes
2answers
79 views

How to automate creation of toe of slope from DEM?

I was looking for an automated process to "identify" the toe of a slope from a DEM and ran across this ESRI thread and technique: I am at Step 7 but have no idea how this is accomplished. I get it is ...
0
votes
1answer
98 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 ...
0
votes
0answers
115 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 ...
3
votes
1answer
458 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
0answers
20 views

Abnormal DEM values after fill operation

With arcmap 10.1. after filling the DEM the value range is -70 to 1078, but it should be between 225 to 1200. Can anyone suggest me a methodology or the necessary steps in arcgis 10.1 to mend my ...
18
votes
2answers
1k views

Proper workflow for LAS to DEM conversion

I regularly come across LiDAR (.LAS) files with elevation data. When I do, I always struggle to find a way of converting them to a DEM for hydrological analysis. I have developed several workflows, ...
2
votes
1answer
119 views

Viewshed analysis and coordinate systems ArcGIS 10.1

I am trying to run a viewshed analysis and I've downloaded DEM data from the UK ordnance survey (Landform-panorama). Since the data is in ASCII format I have created a seamless raster mosaic (and used ...
2
votes
0answers
76 views

choosing the right parameters to interpolate a DEM form contours

this is my first question on the forums, so be gentle :) I have a 5 meter interval contour lines feature class which i would like to interpolate to a DEM. I am well aware of at least 2 tools ("tin ...
1
vote
1answer
77 views

What is the 'water retention capacity' tool and how is it used?

In the latest version of QGIS, I found a geoalgorithim in the processing toolbox that will generate 'water retention capacity.' I am familiar with DEM-based hydrologic modeling tools in QGIS, but I ...
3
votes
1answer
254 views

How to create contours from smoothed DEM instead of using Terrain to Raster?

I'm fairly new to working with lidar and have been assigned the task of creating 2ft contours for the entire county using USGS-provided lidar tiles. Is there a significant difference in the accuracy ...
0
votes
0answers
31 views

Raster Interpolation of Different DEMs in GRASS

I am trying to generate a DEM for surface runoff modeling in GRASS. I have a DEM for the entire watershed at 1ft resolution and another for the small area within that watershed (a parking lot) I am ...
0
votes
0answers
93 views

Strange gdaldem hillshade artifacts

I've downloaded 9 chunks of 1 arc-second NED in IMG format from the National Map. I'm trying to create a hillshade from them. I'm using: GDAL 1.10.0, released 2013/04/24 First, I combine them and ...
4
votes
2answers
219 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 ...
2
votes
1answer
338 views

How do I run the nvis tool in QGIS GRASS?

I am trying to follow this workflow: [How to generate a DEM from a countour Shapefile?] and it's running fine, and when I hit view output or view results I end up with a flat raster with shading ...
3
votes
1answer
227 views

How to create DEM from contours without ArcGIS Spatial Analyst licence?

I'm trying to create a 3d DEM/DTM from a flat contour shapefile which has height data attached to each contour, but I'm not sure how to do this? I've found this post, on creating a dem from contours ...
2
votes
1answer
99 views

How to integrate DEM in Kriging and other interpolation methods?

I would like to see the difference of including DEM in interpolation from without. Some studies on climate data interpolation suggest that interpolation performs better with DEM. How do I do this in ...
3
votes
0answers
61 views

Calculate surface elevation from DEM of pit and known volume with which it is being filled

I am using ArcGIS 10.1. I have a DEM of a pit. I have a known volume of material that I want to put in the pit. I want to know what the elevation of the flat surface of this material will be ...
6
votes
2answers
489 views

How to extract mountain peak points from a given digital elevation model?

For past couple of days, i m trying to determine how many mountain peaks are visible (line of sight) from a given location using POSTGIS. The data i have is DEM for Swiss and address locations from ...
2
votes
1answer
252 views

Spatial Analysis - Calculate a cells elevation (height) above the nearest stream cell

I have searched for some ideas on how to formulate this analysis, but have come up short. I imagine there is a pretty straight forward answer; any help would be greatly appreciates. Data: DEM, ...
2
votes
2answers
221 views

DEM generation from ASTER L1B imagery using FOSS

Is there any (photogrammetric or other) FOSS package to support the generation of a DEM from ASTER L1B products (i.e. combining the spectral bands 3N and 3B)? Are there any practical examples or/and ...
0
votes
1answer
76 views

Viewshed calculation using SQL

Can i calculate viewshed in MS-SQL server? Viewshed analysis is Raster operation. I have elevation value vector observation as point vectors. Are there any methods to calculate Viewshed (using ...
1
vote
0answers
169 views

Merge overlapping DEMs with irregular boundaries

I have a 10m DEM covering part of a state, a 20m DEM covering the whole state, and a 90m DEM covering the whole country. How can I merge them together, getting the best quality available in each area? ...
1
vote
1answer
395 views

What is the highest obtainable resolution of FREE elevation data in the UK?

I am seeking closure with this question guys. I am aware of various sources of free elevation data ~30+ m, and I have been searching for higher resolution FREE data for a while now. This already ...
2
votes
1answer
121 views

How to multiply raster DEM with a linear graph value

I would like to multiply my Raster DEM with a linear graph value y = mx + C. The graph values look as follows: I want to make a new raster where each cell will represent a damage factor from ...
3
votes
1answer
116 views

ArcGis--how to lower a DEM's Z value along a line

I'm a raw newbie, so please excuse the ignorance. I'm trying to do the following in ArcGis 10: reduce the Z value of a DEM along a line. My goal is to "etch" a very shallow line into the DEM ...
0
votes
0answers
114 views

Problem with merging 15 DEM files in ArcGIS

I have 15 DEM files downloaded from USGS website. The pixel depth of each file is 32 bit floating, generic with format FLT. I'm then using data Management Tools > Raster dataset > Mosaics to new ...
1
vote
1answer
113 views

How to compare accuracy of two DEM using GRASS

How do I compare accuracy of two DEM data (lidar and srtm) (possibly through rmse) using GRASS GIS? thanks
2
votes
0answers
21 views

How many function templates can be applied to single image service in ArcGIS for Server?

I am trying to minimize space used on our server by producing a single image service for each county in Maryland. However, I need to display 6 different derivatives for each county: DEM in feet, ...
1
vote
1answer
92 views

Raster Smoothing python [duplicate]

I want to perform raster smoothing on a DEM file. I want to to assign the elevation of each pixel using the average elevations of its 8 neighbors. The ESRI's "Python scripting for ArcGIS" has a ...
2
votes
1answer
183 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?
3
votes
1answer
296 views

How to join 2D polylines and DEM into 3D polylines?

I got a simple question but could not find a satisfactory answer yet: I have a road network in 2D/PostGIS and a DEM. I want to turn the road network into 3D by retrieving the Z-value from the DEM. ...
2
votes
1answer
226 views

Possible workflows for shaded relief representation as vector

I am looking for a good workflow on how to represent relief on a map as vector (e.g. for further processing in Adobe Illustrator or Inkscape). My inspiration is the present google maps at zoom level ...
1
vote
0answers
44 views

Multiple metadata within a single mosaic dataset

I am creating a mosaic dataset consisting of thousands of different DEMs. These will make up a single State, however I need the Counties to be able to hold their own metadata. Each raster contains ...
-1
votes
1answer
61 views

How to craete DSM? [closed]

I need information on Dsm. Applications and ways to do it and the best software and new methods.
2
votes
1answer
132 views

ASTER GDEM v2 coastline generation?

I try to generate world coastline 1:30000 from ASTER's DEM with: gdal_contour -a ELEVATION -fl 0 But above produce some of missing coastlines. Whats happening? Is it cliffy shore? How would you ...