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

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1answer
101 views

Slope analysis of DEM in QGIS?

I have very strange problem with the raster analysis. I have a DEM as a Geo tiff and I do a slope analysis in QGIS. I've done this many times and everything was ok but this time I received reversed ...
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0answers
22 views

building artificial dam in a canyon [duplicate]

I want to calculate the water volume dammed by a dam in a canyon. I managed to calculate the water volume but I actually need a dam in a certain place of the gorge so I can pursuit my calculations. I ...
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1answer
53 views

increase resolution of generated hillshade on QGIS

I want to export a hillshade (geotiff) created from a DEM as an image for printing. But the resolution of the hillshade is way too low (900 colums, 1450 lines). Any way to upscale it? (I tried ...
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1answer
62 views

Bathymetric-topographic DEM color relief?

I am using QGIS 2.12 on a Macbook Pro running OS X 10.10.5. I have an interesting DEM for the California coast (which I downloaded from Santa Barbara, CA 1/3 arc-second MHW DEM. I've been playing ...
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1answer
43 views

Help with Rastercalculator - Filter areas with a certain height difference

I'm struggeling a little bit with the rastercalculator tool of QGIS. At the moment I am working with a DSM and a DTM. My aim is to filter all wind turbines out of the DSM and replace it with the ...
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3answers
334 views

Open LiDAR DEM of the UK with *.asc extension

I've downloaded a tile of a freely accessible LiDAR DEM of the UK from http://environment.data.gov.uk/ds/survey#/download. But I don't know how to open it. The files inside have the *.asc extension. ...
2
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1answer
36 views

applying a gradient to terrain curves in QGIS: problem

I'm trying to apply a gradient to terrain curves generated from a geotiff. I then choose a graduated style with a gradient color palette. everything seemed fine until I noticed that from a certain ...
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1answer
91 views

Reset a base elevation in Pix4D?

Does anyone know how to set a baseline elevation in Pix4D, or is that something that has to happen on the drone-capturing side? The reason is that I have an area which is flown with LiDAR, several ...
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0answers
64 views

Acquiring Digital Elevation Models for Argentina from commercial providers

I'm interested in obtaining Digital Elevation Models for areas in the 20,000 acre range, as I use them to create contour maps for agriculture. The USGS Earth Explorer has a wonderful free DEM ...
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1answer
84 views

ORFEO vs ERDAS: How to extract a good DSM with ORFEO

I'm trying to use ORFEO to check is it suitable to replace ERDAS to perform DSM extraction from stereo pairs. First thing, I can't use ORFEO for complete Pleiades images, it always crashes (my machine ...
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0answers
49 views

QGIS - .vrt DEM layer only partially goes to hillshade

I am using QGIS 2.12 on Macbook Pro running on Mac OS X Yosemite 10.10.5. I have six adjacent DEMs of the 7.5-minute quadrangle size (National Elevation Data or NED, I think). I loaded them into a ...
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0answers
31 views

QGIS problem with converting TIFF-DEM to ASCII

I converted a .tiff DSM into an .asc file. The output-file is stretched increasingly from th the upper to lower part (the dark structure under the classified DEM is the .asc-file). What went wrong? ...
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1answer
91 views

Elevation adjustment DSM using Ground control points

is there any possibility to improve the vertical accuracy of a given satelite DEM/DSM by using exact measured ground control points? And if so, which software is recommended?
3
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1answer
100 views

Calculate Volume over sloped ground in GRASS GIS

I am trying to do some volume calculations on a DEM with GRASS GIS. However, I believe r.volume measures everything from 0. The ground underneath the pile I'm measuring is sloped. I would ...
2
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0answers
37 views

Wanted: A rather large DEM

I am looking for a rather large DEM --- on the trillion cell scale --- to run some tests on. So far, I have found: 200 billion cells: The SRTM Global Dataset 30m DEM 120 billion cells: The National ...
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0answers
55 views

Generating DEM from point cloud and DEM differencing?

I have two point clouds obtained via structure from motion (ground photos of sand-dunes + Visual SfM/Agisoft Photoscan). If I wanted to generate a DEM from these point clouds and difference them to ...
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0answers
25 views

Minus elevation on DEM?

SRTM 30 m resolution data showing -23 elevation and SRTM 90 m resolution data showing -13 elevation at srikakulam dist East coastal side of India where as on google earth it is showing from 2 to 30m ...
2
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1answer
58 views

Clipping DEM / DTED data selecting by extent

similar to a few queries but really struggling to clip a DEM file from say USGS. Going to Raster > Extraction > Clipper and then "select the extent by drag on canvas", does not work. The process ...
2
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1answer
99 views

Combine digital elevation model (DEM) with point layer (QGIS)

I have two layers: The first one is a digital elevation model (DEM) as GeoTiff. The second is a point vector layer (start and end of street segments). What I want to do: Add elevation information ...
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0answers
59 views

What is the usefulness of the angle and direction of the sun parameters in hillshade? [closed]

These parameters refer to the angle as of elevation and direction of the sun hypothetically to the hillshade but why does that must have any importance?
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0answers
38 views

Blend overlapping DEMs using Open Source / Python

I'd like to blend edges of overlapping DEMs such that the join is a smooth transition (for use with InSAR). Apparently the best interpolation kernel for this, according to the literature, is thin ...
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2answers
106 views

Resampling DEM using gdal in python?

Using gdal I want to resample (in this case, oversample) a DEM. The only thing that should change is the pixel spacing, so I want to interpolate in between the values that I currently have. For this I ...
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1answer
168 views

DEM Processing in ArcMap

I have a question regarding DEM. I have downloaded SRTM DEM 30 m and I did a mosaic for the data using Mosaic tools in Arcmap to a Mosaic to a new raster. However, I got a DEM raster with values of ...
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0answers
53 views

Fixing undesirable lines between tiles from SRTM contour line extraction?

I'm trying to make a South American topography map based on SRTM data on QGIS. The problem is a visual one. If the topography contours are extracted from individual SRTM tiles, it results a little ...
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1answer
209 views

Converting LAS 1.4 to 1.2

LIDAR files were released for major part of Slovenia few months back in zlas format. Decompressed LAS format is 1.4 version. I have tried many options how to generate DEMs and had some success in ...
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2answers
162 views

Using DTM slope map to find shortest route between two locations using QGIS?

I've got two locations, A and B, and a DTM covering the region between A and B. Say I want to drive from A to B. I want the shortest route possible, but avoiding regions with slopes higher than, let's ...
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2answers
147 views

Selecting Specific Elevation Areas Contiguous to the Coastline for Coastal Flood Mapping

This is less a problem than an inquiry into a better way of doing something. I am curious how people might go about selecting, say, all areas less than or equal to 10 feet (from a DEM) that are ...
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2answers
487 views

How do I find the slope of road segments with point elevation data of the same linear path

I'm currently working on a project to calculate road grade along roughly 30 miles of highway. I need to isolate and portray all sections of road with more than a 5 percent grade; in hopes of finding ...
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2answers
63 views

How do I generate grid square polygons from a 5m DTM file?

For my dissertation I have collected point features as coordinates and want to relate their distribution around a lake to elevation to see if there is any pattern/relationship between them. I have ...
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1answer
88 views

How to create a series of cross sections in arcgis 10.2?

My ouput should be a series of cross-sections (10 meters apart) along a center line of a river. The input data is a raster data set with elevation values. Can I also automatically generate the lines ...
3
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1answer
66 views

In ArcGIS 10.x, how do I select features of a point shapefile whose z values are above or below the elevations in a DEM?

I have a multi-point shapefile representing earthquake hypocenters (containing depth values) and I have a DEM raster representing an underground surface (the top of the PreCambrian basement). I want ...
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1answer
34 views

How to match river direction with DTM?

I have rivers that some times they do not match their real direction based on the DTM, and they need to be flipped. Is there any way to automatically match river direction based on the DTM in ArcGIS ...
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0answers
43 views

identify and calculate area of valleys

I have a shape file (points) that contains the coordinates of a number of cities in a mountainous area (valleys separated by mountain ridges), and a DEM of the area. I would like to calculate the ...
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1answer
92 views

Finding area of DEM raster clip?

I have a DEM layer in ArcMap 10.2 which I then clipped to fit a large shapefile. I'm trying to find the area of the new DEM shape using the Image Analysis tools, specifically the Mensuration tools. I ...
2
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0answers
49 views

3D model to DEM, maintain volume?

Bit of a challenge here which I've been grappling with for some time. I'll explain my full work flow so you can reproduce if needed. I'm creating virtual landscapes in Google SketchUp which I ...
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1answer
293 views

SRTM vs Google Earth Pro elevation data

I am working on elevation data for an area in Sudan. Between Google Earth Pro and SRTM elevation data, which one is more reliable?
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0answers
44 views

Calculating aspect in flat areas in ASTER DEM with ArcGIS for Desktop?

I have an analyzed aspect surface from ASTER DEM 30m resolution in ArcGIS 10.2. But it shows many aspects in flat area.Normaly it must calculate this are as flat (-1). How can I resolve this problem? ...
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0answers
84 views

Making DEM and Landsat Image Coincide in ArcMap?

I have a DEM with these properties: Spatial Reference: GCS_WGS_1984 Angular Unit: Degree (0.0174532925199433) Datum: D_WGS_1984 Raster Information: Columns and Rows: 3051, 2426 Cell size: ...
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0answers
78 views

Creating a DTM from Contours, via the command line or Python

I am looking to create a gridded DTM/DEM (Digital Terrain/Elevation Model) or TIN (Triangulated Irregular Network) from a set of contours. There are a number of similar questions on both this site ...
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1answer
25 views

Strange Vertical Mapper issue

While using the Mapinfo 7.0+ Vertical Mapper 3.0 on a Windows 8.1, I am facing the following issue: After adding a DTM (in .grd format), which is displayed perfectly, I am trying to use the Grid Info ...
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0answers
66 views

erdas LPS : Load Z values from a DEM?

I'm working on a photogrametric project with erdas LPS version 2013. I succeed in taking several ground control points (x and y values). However, i can't extract and load Z values from my raster DEM ...
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0answers
25 views

Orfeo Toolbox DEM download error

I have been trying to use the following part of the Orfeo Toolbox to download DEM data from usgs. I have been passing it a geotiff image as the reference and am receiving the following error: 2015 ...
2
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1answer
1k views

How to extract DEM files from google Earth/Map for surfer?

I will need to do a 3D representation of a terrain and I heard surfer is ideal, but then I do not have a DEM file of the region, I know Google Earth and Map could help, but I do not know how? If there ...
4
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3answers
257 views

Adding two raster datasets that overlap while maintaining extent of larger raster dataset?

I am using ArcMAP 10.0 How do I add two raster datasets that overlap while maintaining the extent of the larger raster dataset. I have thought of adding zero values to the smaller raster to then be ...
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2answers
74 views

programmatic DEM downloads similar to landsat-util

I recently discovered landsat-util, and was wondering if there was an equivalent command-line application for global elevation data, (for data around 1 arcsecond resolution, preferably geotiff) or if ...
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0answers
117 views

How to make DEM raster in Google Sketchup?

I would like to make DEM in google sketchup, later add 3D buildings and finally convert this file to raster. Afterwards, I want to import this raster to GRASS GIS to make solar maps. It is possible to ...
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0answers
65 views

Las tools vs Geocue for LAS1.3 processing [closed]

I am a user of terra solid products. I have las1.3 data set which i need to perform whole processing in 1.3 version. (I need to supply WDP informtaion and classified las dataset as well. So I afraid, ...
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0answers
12 views

Where to find free DSM data of Switzerland (Ticino)? [duplicate]

I am working on a sonification project. My aim is to sonify data coming from a delimited area in Switzerland. I also would like to print out a 3d map of that region based on that data. Problem is : ...
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0answers
66 views

How to extract area information from a raster based on a DEM or contour lines

I have a raster representing the distribution of a specific land cover type - the raster values are 1 for where the land cover type is present and 0 where it isn't. I also have a DEM with 5m ...
3
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4answers
203 views

How can Identify highs on a DEM?

I have a DEM and I want to find each hill and create a polygon for its area, effectively the out closed contour that encloses the hill. I can do this visually but I'm about to work on a larger area so ...