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

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0answers
55 views

Calculating flow distance of pixel from outlet using R?

I have created these raster files for a river basin: DEM Flow Direction Flow Accumulation Also, I have another raster with values of rainfall. All the 4 rasters have same spatial extent, ...
2
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3answers
284 views

Viewshed Analysis - use DSM or DTM?

I need to run a Viewshed analysis (ESRI 10.2 spatial analyst tool) to answer this: what areas will be able to see a proposed 30m high structure. I have the choice of a DSM or a DTM to use as the ...
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0answers
27 views

DEM Mosaic Dataset Processing - Output Surface and Hillshade raster to same extent as input raster tiles

I have a lot of DEM rasters, tiled adjacent to each other. I would like to make a surface and a hillshade raster to the same extent as each DEM tile. Current issue: processing on a tile-by-tile basis ...
4
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1answer
74 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: ...
1
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1answer
114 views

General guidelines for topographic contour to DEM conversion?

It seems that many different DEM resolutions (10m, 30m, 100m) could be created from a contour map (with, for instance 50m elevation changes marked), but of course some of the resulting DEMs will be ...
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0answers
84 views

How to orthorectify an image from a hilly region without sensor parameters but with DEM and some GCPs in ERDAS or ArcGIS?

I have a raw raster image from a sensor, but do not have the possibility to obtain the sensor parameters. However, I do have a (older) reference ortho image and a DEM with good accuracy. Both are ...
4
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2answers
2k views

Drawing irregularly shaped boundary polygon around set of LAS points using ArcMap?

I am working with a set of LAS data which is irregularly shaped, picture a starfish as the point coverage, surrounding the starfish may be water on one side, may be more land elsewhere but no points ...
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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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0answers
76 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
62 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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2answers
93 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?
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3answers
2k views

Finding elevation differences between adjacent pixels in ArcGIS Desktop?

Is there a way to determine what the difference in elevation is between two adjacent pixels? I am using an SRTM DEM to map faults. I am using the vertical error (>16m) as a criterion for the ...
2
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1answer
37 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 ...
7
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3answers
1k 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 ...
0
votes
1answer
85 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 ...
2
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1answer
61 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 ...
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0answers
54 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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1answer
98 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?
4
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1answer
2k 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 ...
7
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1answer
7k views

Where to acquire elevation data for UK?

I'm looking for digital elevation data for UK. Does anybody know if there is a good service providing data for free that are of better accuracy than ASTER-DEM that is around 30m and if not what is the ...
2
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0answers
38 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
61 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?
32
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7answers
24k views

Choosing 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 ...
0
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0answers
61 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 ...
2
votes
1answer
113 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 ...
0
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0answers
29 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 ...
5
votes
2answers
255 views

Sun azimuth on shaded relief LiDAR maps

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 that I need to alter but I don't know how. ...
5
votes
1answer
293 views

How can I get the profile graph on ArcMap to display specific points?

I currently have 2 layers: 1) DEM of existing terrain 2) Polygon in vector format of future water retention basin I need to draw cross sections across this basin for eventual cut and fill calcs. I ...
3
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0answers
41 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 ...
5
votes
2answers
4k views

Viewsheds and Observer Points in ArcGIS Spatial analyst

I am trying to understand the viewshed and observer points tool in spatial analyst. I want to show which areas of land can see a wind turbine, or put another way, from where can the wind turbine be ...
9
votes
2answers
255 views

Cleaning blocks pattern from urban LIDAR (blocks uplifted from streets)

We have a 1-meter LIDAR DEM from a city. A small subset can be downloaded from this link: This screenshot shows raw DEM with gray palette (darker belts are streets, and greyish and whitish ...
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1answer
190 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 0-...
4
votes
1answer
257 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
179 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
164 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 ...
9
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5answers
2k views

Are there any open source tools to detect and fill sinks on a DEM?

Are there any open source or inexpensive tools to detect and fill sinks on a DEM? ArcGIS Spatial Analyst is just out of my price range.
3
votes
2answers
68 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 ...
0
votes
1answer
116 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 ...
5
votes
1answer
6k views

Labeling contour lines in ArcMap [duplicate]

Can anybody give me advice on how to label contours as shown in Figure 2 below? I would like to be able to put the label "on" the line, which is easy enough. But I'd also like for the contour line to ...
3
votes
1answer
75 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 ...
1
vote
1answer
37 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 ...
3
votes
2answers
422 views

Filling voids in ASTER stereo-images for DEM generation using ArcGIS Desktop?

I'm trying to use a stereo-pair of ASTER images to generate a DEM (in ERDAS Imagine). However, the mountains are rather cloudy and the images can't be used as they are. But the relevant parts (valley ...
2
votes
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 ...
1
vote
1answer
111 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 ...
1
vote
1answer
359 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?
2
votes
0answers
53 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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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?
4
votes
3answers
301 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 ...
0
votes
0answers
91 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: 0....