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

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1answer
35 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
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2answers
3k 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
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1answer
440 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
208 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
268 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
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2answers
117 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
301 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
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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
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0answers
472 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
251 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
98 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 ...
3
votes
1answer
157 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
91 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
675 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
401 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
152 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
26 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 ...
2
votes
2answers
82 views

Is there any way to 'clean' up ASTER v2 DEM data?

I downloaded all the tiles I needed, then plotted them to find that they don't all seem to have the same quality. Basically, you can see all the edges of a lot of the tiles. Is there any way to clean ...
3
votes
2answers
1k views

Colouring areas between (vector) contours?

Is it possible to colour areas between (vector) contours without making it a DEM first? Joshdoe seems to have done so in Create filled contour map with GRASS but does not say how.
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0answers
38 views

Contour command in Spatial Ecology's GME

Has anyone been successful using the contour command from GME (Geospatial Modelling Environment)? I'm trying to create contours out of a DEM. I know you can do it in ArcGIS with 3D or Spatial Analyst ...
1
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2answers
80 views

How can you create a depth raster from a DTM and a polygon in QGIS?

I have a DTM raster and a flood outline in polygon format - how do I create a depth raster for the flood outline (i.e. flood level minus DTM level)?
4
votes
5answers
1k views

Calculating Runoff / Streams using DEM in ArcGIS

I am just curious about the workflow that many of you use for runoff/stream analysis using a DEM and create a "water network" from the results in ArcGIS 10.1? I know the average rainfall for different ...
6
votes
1answer
170 views

Ditch Extraction using LIDAR DTM (1m resolution)

I'm trying to extract ditches using the LIDAR DTM using the software eCognition but I am actually having a hard time since the paper where I based my workflow entitled "Ditches’ network extraction and ...
1
vote
1answer
105 views

How to use ArcMap for HydroPower Potential

I am trying to determine the sites for small hydropower. I have a elevation dem, rainfall data, Curve number data (from soil and landuse shapefiles). I have already used the DEM to fill sinks, find ...
4
votes
0answers
44 views

How to calculate an Illumination raster for fire ignition danger analysis?

I am doing a fire ignition danger analysis using this equation that I found in Millington (2012) http://www.jmecology.com/wp-content/uploads/2014/03/33-42-MILLINGTON.pdf IR = 4H + 3V + 2I – E Where: ...
3
votes
1answer
2k views

Convert DEM to STL (3D Printer Format)

I have a DEM in ArcGIS 10.1 that I would like to get into STL format for a 3D printer. Does anyone know some software that will allow me to make this conversion? I have to use the STL format because ...
2
votes
1answer
294 views

How to create contour lines from point data?

I'm using QGIS 2.4.0 and I have a shapefile of points with elevation data and X and Y coordinates. I'm using windows 7 OS. The idea is to create a contour line SHP using my point data. My question ...
2
votes
1answer
153 views

How to create a catchment from a point using a DTM raster in QGIS?

I need to find a better way to delineate a catchment from a given point on a watercourse using a DTM - currently I am either using FEH, or if the catchment is too small using contours to draw ...
8
votes
1answer
204 views

River boundary (bank) extraction from LiDAR

Is there any way to extract a river boundary (bank) from LiDAR data and its products (DEM, intensity image and slope) automatically? Digitizing is very time consuming.
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votes
3answers
55 views

Mosaic to New Raster tool fail

I'm trying to merge 24 DEM files, after applying the tool (Mosaic to New Raster) only 11 out of the 24 merged. All the original files are in the same projection, pixel type, band, etc. I also ...
4
votes
0answers
97 views

Simplified flood “model” / estimation from elevation data

The goal is to present an estimation of potential flooded area. But still keeping it simple. I know this will not be accurate. The question is: will it be good enough for at gestimate / rough ...
2
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1answer
27 views

Finding DEM/HIllshade sources California

Creating watershed maps for schools. I want to color ramp the elevation to show low and high points. What kind of files do I need and where to find them?
21
votes
2answers
2k 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, ...
5
votes
1answer
203 views

Interactively determining upslope and downslope areas on DEM?

I know SAGA GIS can be used to interactively generate maps of upslope and downslope areas for a cell within a DEM, but the output is pretty ugly. An upslope area is defined as all cells (for a ...
0
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1answer
80 views

Extract elevation data from Landsat / MODIS imagery?

Just curious, have anyone tried to extract elevation data from LANDSAT or MODIS imagery? So far, I came across one journal by Toutin who did so using adjacent LANDSAT 7 imageries. Results seem pretty ...
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1answer
122 views

Automatic Lineament Extraction from satellite images using ENVI? [closed]

Can you tell me the steps of automatic lineament extraction from satellite images? Can ENVI perform edge detection and the lineament extraction?
3
votes
1answer
57 views

Grid-like artifact visible in contour layers?

I am creating contours from an Aster DEM in ArcMap 10.1 I see a grid pattern appearing, particularly in areas of dense contours: I see the same artifact if I create a Hillshade layer so presumably ...
0
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0answers
65 views

Striping Artifact in Aster DEM Mosaic

I'm working with SRTM and ASTER data for a university project. My goal is to delineate watersheds and evaluation of these with ArcGis 10 and ArcHydro. But a striping error occurs with the flow ...
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0answers
36 views

How to extract elevation data from ASTER/SRTM? [duplicate]

I just want to know if there are any other tools available in QGIS apart from the Point Sampling tool to extract elevation data from ASTER/SRTM/CartoDEM (for India) data? When I convert these images ...
15
votes
11answers
24k views

How to a convert LiDAR XYZ files to DEM / DSM?

Normally consultants (LiDAR survey) provide me with data to my specifications; already in ESRI GRID or ASCII GRID format. This way LiDAR data can be easily used with ArcGIS. This time I only have xyz ...
0
votes
2answers
47 views

TIN to Raster - specify raster's origin

How could I specify raster's origin, while using arcpy.TinRaster_3d?
0
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0answers
10 views

Editing height of DEM raster using the adjacent cell values [duplicate]

I have a high elevation as 35m, but surrounding area height 6m/7m..I need to adjust that DEM (18m to 35 m) height using the adjacent area height. How could i edit the DEM raster? I hv been trying to ...
5
votes
3answers
886 views

How to drape a simple jpeg image over dem of some area?

How can we drape a simple jpeg image which doesnot have any geo referencing information over the digital elevation model in order to visualize it in 3D in QGIS?
0
votes
1answer
22 views

Is it possible to reveal the relief parameters “slope inclination” and “slope exposure” by dint of ASTER GDEM?

I’m trying to find information in technical and scientific articles – is it possible to reveal the relief parameters “slope inclination” and “slope exposure” by dint of ASTER GDEM? Or we can define ...
3
votes
2answers
93 views

How to manipulate lidar map using sun azimuth

Hi I am VERY new to QGIS and am struggling. I have a Lidar map and want to change the view so that the ground shadow is manipulated (looking for archaeological anomalies). I think it is the sun angle ...
0
votes
0answers
15 views

Holes in Rasterized DEM from QGIS [duplicate]

I converted vector contours to a raster DEM using the rasterize command in QGIS. Generally the DEM looks correct, but the are a large number of holes in the DEM. The holes have a value of zero when ...
2
votes
1answer
78 views

Rasterizing Contours - How to remove 0 values

I want to convert vector contours to a DEM. From other posts, I wanted to utilise the Grass r.surf.contours tool. Initially I converted the vector contour layer to a rasterized contours using the ...
3
votes
0answers
104 views

Creating one DEM from multiple ASC files

I am struggling with this several days and now its time to ask how to do it in QGIS. I have very detailed 27 ASC grid files with overall size of 9 GB created from 1m contours of large area (600 m2). ...
2
votes
1answer
35 views

Algorithm behind custom tool of ArcGIS for Desktop called xyz2grid21?

I am a researcher from Romania and I have used xyz2grid21 ArcGIS tool (by Min-Lang Huang) in order to convert xyz files (LIDAR data) to ASCII and ESRI grid in order to obtain a DTM. I need to know ...
3
votes
2answers
60 views

Is SRTM 3 second arc free of non-terrain features?

I made an elevation map of my study area in Macapa, Brazil. But the region has the average elevation lesser than 30 m as I can see from my map derived from SRTM 3 second arc. According to my ...