For questions about Digital Elevation Models (DEM), Digital Terrain Models (DTM) and Digital Surface Models (DSM)

learn more… | top users | synonyms (2)

1
vote
0answers
30 views

Flattening topography while retaining structures in QGIS?

I have a set of Terrain data in both DSM and DTM form. What I am trying to do is extract the features (buildings, hedges etc...) that have been removed from the DTM, but I don't want the topography. ...
0
votes
0answers
12 views

Resampling using gdalwarp gives me no data

I have an image with the following information. Driver: GTiff/GeoTIFF Files:test_DEM.tiff Size is 91, 73 Coordinate System is: GEOGCS["WGS 84", DATUM["WGS_1984", ...
0
votes
0answers
43 views

Extract from DEM base on range of values in ArcGIS or QGIS

I have a very large 0.5-meter DEM and would like to extract a specific region of elevation values... e.g. I've tried creating a contour map but that was taking way too long- >24 hours.
2
votes
1answer
34 views

What is NOS Hydrograph sounding data?

How can sounding data be used for bathymetry when depth is positive? I have downloaded DEM (digital elevation model) as shown in the image below but need bathymetry data for H. All I have found for H ...
2
votes
1answer
57 views

Failed DEM via Natural Neighbor in QGIS 2.14.2-Essen

Following the indications of Monde Geospatial (https://www.youtube.com/watch?v=bLbY3iMBW-A) I created a CSV file with the altitudinal data (Google Earth) for 2182 total points and imported it into ...
1
vote
1answer
30 views

How to use HGT files in MapInfo

I have a SRTM-3 file and I want to use it to make a DEM of the related world region. I'm using MapInfo Professionale V8 and I'm fairly new to that software, so if there is any tutorial that shows how ...
1
vote
1answer
53 views

Converting resolution to meter using ArcGIS for Desktop?

I have data in the following format: Projection: Latitude-Longitude | | N: 46:08:44N S: 45:54:50.666667N Res: 0:00:00.333333 | | ...
0
votes
0answers
31 views

Aligned shapes to DTM - CityEngine

I have an issue with the road and parcel layers aligned to DTM in CityEngine. As the following image shows, there several changes in the height in some parts of the model because of the DTM. I have ...
1
vote
1answer
56 views

How to select lines affected by sea level rise?

I'm doing a part for my master's thesis where I'm trying to find out which sites located near the coasts of Sweden that will be affected by sea level rise. I got a DEM with height data and have to ...
0
votes
2answers
58 views

How can I work with large DEM in GIS?

I have a very large DEM (about 115Gb). I cannot work with it on my computer. I need to clip a river catchment from this DEM. I work in GIS. How can I do this?
0
votes
1answer
56 views

Is there a technique to calculate volume using a polygon instead of contour line?

What I'm attempting to do is calculate the volume of a lake using a polygon I created by classifying an image for water. I then extracted the polygon from the classification process. What I'm left ...
1
vote
2answers
49 views

Making raster DEM from irregular points shapefile in QGIS?

I assume that first I need to interpolate and then somehow turn it into raster in QGIS?
5
votes
2answers
103 views

Improve DTM under forested areas without smoothing?

I'm using a DTM retrieved from LiDAR data and I noticed that forested areas are grainy or not defined. The DTM data was retrieved from geostore.com. Here is one example: Is there any way to ...
1
vote
1answer
49 views

How to convert bathymetry sounding data to DEM (digital elevation model)?

https://www.ngdc.noaa.gov/docucomp/page?url=http://surveys.ngdc.noaa.gov/mgg/NOS/hsmdb/H04001-H06000/H05455_hsmdb.xml&view=hydro/survey&header=none I downloaded the bathymetry sounding data ...
1
vote
1answer
71 views

Measuring Volumes using DEMs

I've done quite a bit of research here and elsewhere and am still having trouble coming up with a solution for measuring volumes using a DEM derived from high-resolution (1 m) stereo satellite imagery....
0
votes
0answers
28 views

Getting latitude and longitude in decimal degrees from DEM-raster in UTM

I have a digital elevation model (details: ~4300 cols x 3600 rows, cell size 10 m x 10 m, tiff format, projection: WGS1984 UTM, false_easting: 500000, false_northing:0). I would like to have 2 ...
6
votes
1answer
212 views

In hydrologic terrain analysis is there a difference between “pits”, “depressions”, and “sinks”?

In hydrologic terrain analysis is there a difference between "pits" and "depressions"? For instance, Planchon and Darboux (2002) state The usual numerical methods for removing the depressions of ...
2
votes
1answer
82 views

Calculating total area overlapping specific raster DEM color interval whose boundaries are confined by another vector?

I know this sounds quite difficult, but maybe it isn't for you or at least it shouldn't if I explain it correctly. (I'm using QGIS 2.14) I'd like to know to calculate total area overlapping a ...
2
votes
1answer
45 views

Reverse colour-ramped DEM to its original elevation value?

A have a GeoTIFF LIDAR image which display DEM in its color-ramp version (color relief) from blue (minimum value) to red (maximum value) and green (in between). I don't have the original elevation ...
0
votes
1answer
126 views

How do I convert a DEM GeoTIFF to Contour Shapefile

I have a digital elevation model as a GeoTIFF and I'm looking to generate a Shapefile of contours with 5m bands on the command line. Is this possible? Ideally using GDAL and Python.
2
votes
2answers
75 views

Topography data to elevation raster

In a previous question (convert-xyz-points-to-topography-and-calculate-mean-slope), I asked how to interpolate point elevation data to a raster in order to measure slope. Thus I use the Raster > ...
1
vote
1answer
27 views

CRS and Spatial join problem

I try to match two layers. First one is point-type with cities in Europe. Second one is grid layer (polygon) with elevation value. What I want to achieve is to to join the "Z" value from grid layer to ...
4
votes
1answer
80 views

30m/10m/1m resolution DEM for microtopography research

I am conducting research in a region of Illinois that does not have a LiDAR dataset. I am looking to develop a fine scale habitat species distribution model; however, the coarse data available (30m/...
3
votes
2answers
110 views

How to calculate the relative share of an area of a circle that has a slope >15% in Germany

I need to calculate the share of buildable land for the 15 major german cities within a 50 kilometer radius of the city center. Part 1 of the definition buildable is that the area must have a slope &...
1
vote
1answer
69 views

Add DEM layer to Leaflet

I want to add a digital elevation model (DEM) layer to my leaflet map and access the height data through javascript, i.e. I cannot use .png files or qgis2webplugin but rather .tif or some compressed ...
1
vote
0answers
28 views

“Select a tool” error Saga: Accumulated cost (isotropic)

I'm trying to run Saga's accumulated cost operation in QGIS on a DEM and set of raster destination points, but keep receiving an "Error: select a tool" in the log after a failed run. There are no ...
0
votes
0answers
25 views

QGIS asc to GeoTIFF error: “File short, can't read line 3687”

I tried to convert an asc file to GeoTIFF and I had the following error: ERROR 3: File short, can't read line 3687. ERROR 1: (..:)/mdt.asc, band 1: IReadBlock failed at X offset 0, Y offset 3687 ...
1
vote
0answers
46 views

QGIS: How to create a crosstab using SAGA toolbox cross calssification and tabulation?

I am trying to use Cross classification and tabulation SAGA toolbox. I have a raster DEM file (14 classes) and raster file precipitation (13 classes). I want to do cross-tab - but I don't know how ...
1
vote
0answers
25 views

Applying values to highest terminal segments in channel network using PostgreSQL?

I extracted a channel network from a dem but due to some technical difficulties the layer had some discontinuities. So after filling them, i suddenly realised that the Strahler orders it gave me were ...
4
votes
2answers
201 views

Faster way to calculate slope between two points on DEM using ArcGIS for Desktop?

I'm a forester, and I do lots of work with LiDAR derived DEM's. I'm looking for a quick-and-easy tool to calculate the slope between two points. The application for this would be drawing a proposed ...
2
votes
0answers
59 views

Draw raster on top of a Leaflet map

I want to implement a raster layer on top of a Leaflet map that includes the following functionalities: Digital Elevation Model (DEM) terrain height included in each raster cell GPS-Track (I use ...
2
votes
1answer
53 views

How to calculate mean elevation in a DEM between a specific interval?

I have a DEM with different elevations between 100 m & 3828 m. I just want to calculate mean elevation higher than 1500 m? Can I do that?
1
vote
1answer
46 views

Hillshade effect not working when no data is on screen

I'm working on a DEM and I selected hillshade effect to be active. The problem is that I can't get it to appear when a no-data area is shown on my screen. If I move the area just enough for the no-...
4
votes
1answer
41 views

Grid size of a Digital Elevation Model developed from topographic surveyed elevation contour line?

I have generated a Digital Elevation Model from elevation contour line. I got these elevation contour line at 20 cm interval from DGPS survey. What would be the grid size of generated DEM in "m". ...
1
vote
1answer
77 views

Raster calculator fails with large raster in QGIS

I'm working in QGIS 2.14.1 with a DEM ranging from 200 feet to 1600 feet elevation called "dem_3m_Zft1b" (geotiff, 16822 X 33349 cells, No-data =-9999) If I enter "dem_3m_Zft1b" > 0 in the ...
2
votes
0answers
39 views

Watershed delineation with meandering river

I'm using ArcGIS (Hydrology toolbox) for watershed delineation for a number of pour points, and I'm running into problems with very meandering rivers on extremely flat alluvial land (Amazon basin). ...
3
votes
1answer
55 views

Scripts to automate conversion from DEM to contour shape files

I am using the DEM files in the Cornell CUGIR repository to build contour layers in QGIS. The problem I have is that while it is easy to do, it requires many manual steps in QGIS that are both ...
2
votes
1answer
31 views

contour lines/ basement contour extraction

My purpose: getting out area between elevation contours (like b/w 600m and 700m). The contours could either be elevation ones or the basement contours. I got elevation contours using spatial analyst ...
2
votes
1answer
34 views

Applying base heights to raster is giving me different results

I have applied the DEM's base heights to both the raster image, the raster DEM, and a vector file. The DEM and vector file match up but the satellite image does not match up at all. Any suggestions ...
1
vote
0answers
50 views

SAGA GIS Channel network crash

So, i had this very weird bug while treating my dem data lately. I used SAGA to create flows channel networks on a dem i acquired a little while ago. Preprocessed it using sink route detection and ...
1
vote
1answer
48 views

How to do diagram block with open source software?

I would like to do a block diagram (topographic and geological representation). Is it possible to do this with QGIS (or other open source software), in Windows 7?
2
votes
1answer
39 views

How to calculate the right area in polygons with help of DEM?

I have used infra red photos to identify territories in Norway where I have drawn polygons for different vegetation. I wonder if there is a way to use the polygons with elevation data to get the exact ...
1
vote
1answer
48 views

5x5 raster filter in ArcGIS?

Normally, I am using the 3x3 lowpass filter if I need to filter a DEM. However in one case, for better results in curvature calculations, I would like to do a 5x5 filtering. How is this possible in ...
3
votes
1answer
38 views

Do outputs (shp, dwg) inherit vertical datum from input (las) files?

I'm working in ArcMap. I pulled LiDAR data off earth explorer and created a DEM with the LiDAR data. I then created contours as a SHP file and exported to DWG (CAD). I was asked if the CAD file's ...
0
votes
0answers
37 views

Is it valid to resample a raster from 1m to 3 feet?

I know that in general it is not a good idea to up-sample. I am curious if it would still be be a "bad idea" with a minor change like this from 1m resolution to 3 feet? Going to 3 feet would not ...
0
votes
1answer
60 views

Get Elevation of XY points [duplicate]

I am working with ArcMap 10.3. I have imported DEM files. When I imported the files they had the extension of .DDF. I would now like to be able to take a list of XY coordinates and, for lack of a ...
0
votes
1answer
53 views

How can I blend DEM rasters with GDAL?

I have several DEM rasters in different projections and at different resolutions. The rasters are not rectangular, but they have appropriate NoData values. They overlap enough that I should be able ...
1
vote
1answer
68 views

How to speed up raster2pgsql?

I'm trying to upload a 37 GB raster dataset to PostGIS. The raster is out-of-db (-R option), so the actual pixel values are not stored in PostGIS. I'm using this command: raster2pgsql -s 25833 -C -I ...
7
votes
4answers
323 views

Extracting Values to Points without ArcGIS Spatial Analyst?

I have a raster DEM & multiple points. I want to determine the DEM elevation at each point. Other than manually examining the DEM at each point, (very time consuming with lots of points) is ...
2
votes
2answers
184 views

Where is the nviz tool in qgis 2.14 with GRASS 7.0.3?

I hope Im not blind but I looked in the grass tools (modules) and qgis plugins but couldnt find it. When i try to run nviz from GRASS the whole programme chrashes just before concluding. Its a ...