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

learn more… | top users | synonyms (1)

1
vote
1answer
56 views

Digital Elevation Model Resolution

While I creat flood areas using DEM in ArcGIS, Which parameters do I consider to determine DEM's pixel size and resolution?
24
votes
7answers
10k 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 ...
3
votes
1answer
151 views

How to calculate and compare RMSE between two DEMs?

I'm doing a project based on using Lidar point cloud data and I have access to a DEM that cover all of Sweden. But my goal is to produce several DEMs covering a small area using different ...
1
vote
2answers
127 views

How to create DEM from Lidar point cloud data?

I'm using ArcMap and I want to create DEM(s) over an area to have different outputs depending on which settings/filters I put in. I have access to laser point cloud data as my input files. I've worked ...
1
vote
1answer
193 views

How to calculate the river slope for a lot of rivers automatically in ArcMap?

I'm working with ArcMap 10.2 and I'm pretty new in this area.. What I want to do is compute the river slope for a lot of rivers from a DTM...I know that there is a way to do it manually passing by ...
1
vote
1answer
44 views

Creating Dem from cross sections

I have a question I appreciate that if someone can help me I have a DEM in arcmap and cross section of a river which flows on the Dem in Hecras. I now the cross sections are more accurate. I want to ...
2
votes
1answer
83 views

How to convert different lidar data formats to raster DTM and measure its geographic position accuracy?

I'm trying to generate a DTM from lidar data and I'm new in the this field. I have different kind of files which describe the same area (different versions): *.dtm *.xyz *.xyz with variable grid ...
4
votes
1answer
66 views

Problem of irregular contour from a DEM

I've created contour lines every 5 meters from a grid DEM with 5x5 meter of resolution. But strangely I've obtained that the contour lines are segmented and rich of lines that goes up and down, ...
4
votes
1answer
302 views

Download new SRTM 30 meters

I read about the new version of the digital elevation model at 30 meters (SRTM 30 meters), but I can not find from were I can download it. some sources: ...
1
vote
2answers
54 views

Contour of single feature on QGIS

I'm trying to extract one single contour line at given elevation from a DEM. Taking into account that I want only one contour and not all contours with the given elevation, is there a way to do it in ...
2
votes
0answers
29 views

infer the altitude from a DTM & finally provide it to point / evincere la altitudine da un DTM & finalmente fornirla a dei punti

I would like to complete a point vector's table with Z data. I am not able to take Z coordinate from a dtm (downloaded from ...
3
votes
2answers
50 views

Digital Elevation Model and Shapefile not aligned in openWind

I have a digital elevation model and a shapefile containing point features for the location of wind turbines. These two layers appear to be aligned in QGIS but when I open them in openWind, they are ...
1
vote
1answer
163 views

QGIS Slope Classification Issues

I am very new to QGIS for the primary purpose of creating a slopes layer so we know where slopes are above 15% or 20% or whatever we finally decide. I have used our DEM to create a slope geotif and ...
2
votes
1answer
120 views

How can I create an DEM from Point-Data

my boss gave me a small 3D-point-shape-file and asked me to make an DEM from it, wich I should put together with an older DEM of the same site, wich was made with Surfer. I created a raster-layer from ...
2
votes
1answer
235 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 ...
2
votes
0answers
80 views

Command line tools to generate elevation profile from DEM + GPX/GeoJSON

I'm looking to generate elevation profiles from a number of GPX traces (which I also have GeoJSON conversions of). I have 20m resolution DEMs of the area, in GeoTIFF format. Ultimately I want to ...
2
votes
2answers
108 views

QGIS, interpolate along an irregular shape or line to create a DEM

Before anyone marks this as a duplicate, hear me out. This question: Interpolation: irregular shape, merging DEM's asks my question but not for QGIS. Furthermore, the answer is vague and not ...
4
votes
1answer
123 views

Highest resolution Digital Elevation Model for the UK?

I need the most precise and highest resolution free digital elevation model for the UK. Would OS terrain 50 or ASTER GDEM be more suitable for view shed analysis?
2
votes
2answers
166 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. ...
4
votes
1answer
151 views

Creating a point corresponding to the maximum elevation of a DEM [duplicate]

I am wondering how can I create a point corresponding to the maximum elevation value of a DEM. I mean, from the DEM I can easily get the maximum elevation. For the sake of a viewshed analysis, I would ...
2
votes
2answers
54 views

How to Clip a DEM and retain DEM format?

I have a DEM file that I downloaded from the internet. I am trying to clip it to reduce the file size. So far I have tried two different methods, but neither of them produces a clipped file in DEM ...
8
votes
2answers
127 views

What is a good metric for mapping accuracy

I have recently received a dataset that supposedly mapped the altitude a given region (a DEM). I would like to determine the accuracy of the new map by comparing it with a previously generated DEM. ...
2
votes
0answers
27 views

Drawing boundary through DEM of glacier valley using ArcGIS for Desktop?

I want to calculate/draw the boundary extent in Glacier valley with the help of DEM. Can you please guide me which is the best tools in ArcGIS and steps to calculate.
6
votes
3answers
209 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
vote
0answers
49 views

Inverting color ramp in legend

I have inverted the color ramp to display land surface elevation, now when I add a legend in print composer it shows the lowest value at the top and the highest at the bottom. See below: It is more ...
4
votes
1answer
142 views

Shapefile and DEM: check rivers behaviour

I'm working with shapefiles representing rivers (rivers.shp), and DEM for the terrain elevation (terrain.tif). Basically, I want to check that my rivers (stored as polylines in my shapefile) behave ...
1
vote
1answer
67 views

Reclassification of raster surface using ArcGIS for Desktop?

I have a raster surface with values ranging from 0 -100. I want to create a categorical classification (percentage categories of 5%, e.g. 0-5%, 6-10%...) and reclassify my surface into these ...
5
votes
1answer
223 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 ...
3
votes
1answer
731 views

Solar radiation calculation from GTOP030 DEM image

Can you help me to calculate solar radiation from GTOPO30 DEM image at the 30 m spatial resolution. I'm trying to do this many times using spatial analysis solar radiation calculation tool in ArcGIS. ...
3
votes
0answers
68 views

Intersection of a vector linestring and underlying DEM

Following is an screen-shot where ASTER DEM raster layer has been overlaid by a road linestring vector layer. I want to extract those DEM pixels which are lying exactly beneath the linestrings. I want ...
1
vote
0answers
22 views

Buffering/extrusion of a dem surface

I have a surface representing a DEM and i would like to add it some thickness. If i simply duplicate the surface and translate it down by my thickness, i get non uniform thickness, ie thinner where ...
3
votes
0answers
25 views

3D distance and topography

I have a set of points and want to find out the nearest distance to a water body (poly lines) taking into account the terrain and get a surface distance calculation. I understand that the way is to ...
1
vote
1answer
119 views

Stretched raster symbology not working in ArcGIS for Desktop?

I have some DEM rasters (from the same data source so I think they're uniform in all file specifications) that I'm symbolizing using the same stretched color ramp. I set the stretch type to min-max, ...
2
votes
1answer
37 views

QGIS vector layers do not match DEM?

I have a DEM (saved as a .tif) and, using QGIS, I want to clip the DEM using a vector mask. The function will not work. Am I missing critical step?
4
votes
2answers
4k views

How to generate a DEM from a contour Shapefile?

I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
1
vote
1answer
498 views

Fill sinks error in arcHydro

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 ...
5
votes
3answers
229 views

Normalizing point cloud data

How I can get Digital Height Model (only object heights, DSM - DTM = DHM)? Many applications can do this, but they convert it to GRID or TIN format. I was wondering if it was possible to keep the ...
13
votes
3answers
281 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 ...
6
votes
2answers
123 views

Reducing elevation from DEM using ArcGIS for Desktop?

I am so curious how would I strip off elevation from the DEM. I don't know how I would explain it further but I have attached an image to clarify this. I wanted to eliminate the area shaded with ...
-3
votes
1answer
407 views

How to extract drainage line network from GRASS GIS and QGIS [closed]

Giving DEM as input is there any way to get drainage network? I am newbie to GRASS and QGIS ,provide any working examples in GRASS GIS and QGIS with procedure.
1
vote
0answers
18 views

Where is it possible to download a DEM for the Romanian east carpathians? [duplicate]

I'm quite new to GIS and have only done a few small tasks for Projects at University and the required data has always been provided. I am now struggling to find the specific DEM I need. Also other ...
3
votes
0answers
485 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 ...
2
votes
3answers
304 views

How to determine bare earth from unclassified LAS file

I have data in LAS format with RGB values created from Aerial photogrammetry using a UAV. I am trying to find a solution to extract the bare earth to create my DTM from the DSM. I have tried SAGA, ...
2
votes
0answers
99 views

Choosing the right parameters to interpolate a DEM from 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 ...
4
votes
1answer
190 views

Topographic Index - Why is upslope contributing area divided by downslope contour width and not upslope contour width?

In the Topographic Index calculation, a is the upslope contributing area per unit contour length. Is the "unit contour length" calculated from examining the contour widths of the downslope cells that ...
2
votes
1answer
112 views

shapefile to gmt format

I have an ESRI shapefile of the contours of my study area, and I want to convert it into a format that is acceptable by GMT, so I can make an elevation map of my study area. Is that even possible? ...
4
votes
2answers
686 views

Comparing two TINs created using ArcGIS for Desktop?

I have the following two files: LiDAR las file1 Let's give it a name LiDAR las file2, contains the same file1 data, where number of points randomly removed. So if file1 contains X number of ...
5
votes
3answers
420 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 ...
2
votes
1answer
175 views

Negative Topographic Index Values

I am getting negative topographic index wetness values in SAGA GIS - anyone else every get this? Not all negative values, but the minimum of the TWI range is negative for some steep watersheds we are ...
1
vote
1answer
30 views

DEM error when trying to do topographic correction in GRASS

I'm new to GRASS gis and I'm trying to do a topographic correction (i.topo.corr) of 9 ASTER bands using SRTM dem. I keep getting this error message: ERROR: Illumination model is of CELL type Is ...