Questions tagged [elevation]

The vertical distance of a point or object above or below a reference surface or datum (generally mean sea level).

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822 views

Calculating slope and aspect from DTM lidar elevation data in ArcGIS Desktop? [closed]

I have an ASCII 2m lidar DTM file which I converted into a raster in ArcGIS with the From ASCII to Raster tool. From this DTM file I would like to calculate the slope and aspect. I have used the ...
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1answer
398 views

Merging raster elevation data

Using QGIS I have to merge 416 raster files with elevation data, at the beginning I´m using with only 4 of them to try out: When using "merge" (Raster > Miscellaneous) the result are a file with only ...
4
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0answers
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SRTM elevation data question [closed]

I have a question concerning the SRTM elevation data (http://srtm.usgs.gov/). As a little thought experiment, assume I want to build a 3D model of the earth's surface as a point cloud. The earth's ...
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2answers
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How do you convert SRTM HGT elevations from WGS84 into meters above sea level?

I am building a JavaScript script that reads binary HGT files - as generated by the SRTM - and converts the data into bitmaps viewable in your browser. You can try out the script and view the source ...
3
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1answer
7k views

How to conditionnally assign a new value to pixels of a raster image?

Given a topographic GIS raster of one country crop.tif: Given a know pixel value such as elevation (z) is +73 : $ gdallocationinfo crop.tif 1 1 -valonly > 73 Given an elevation threshold n = 50 (...
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1answer
772 views

Why not measure elevation from the center of the earth?

In trying to understand Geoid vs Ellipsoid height, I ran across this page. One of the claims is: Zero elevation as defined by Spain is not the same zero elevation defined by Canada Basically, ...
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3answers
697 views

What is Trinity High Water?

This question may be off topic, in which case I apologise. I have a problem where water level is important and I have two water levels defined, Trinity High Water and Mean High Water springs (MHWS). ...
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1answer
3k 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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2answers
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Reading elevation data from WMS response?

I am trying to get elevation data from the tile received from USGS server. I query the data using Image Format image/Png. When I read the data I get color values. I need to know how to read the ...
3
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1answer
182 views

Generating a buffer of a vector line based on raster values where the vector intersects a raster

I am trying to figure out how to buffer a vector shapefile with a variable distance (in QGIS). However, the variable distance needs to be dependent on the value of a raster (DEM) where that vector ...
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3answers
4k views

How to update the Z value using an UpdateCursor?

I have created the following script to mimic the ArcGIS 3D Analyst tool, FeatureTo3DByAttribute, which creates a 3D copy of a 2D feature class and sets the Z to a specified attribute. import arcpy, ...
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1answer
81 views

Changing elevation values of DEM

I am no expert in QGIS and I've already spend quite some time to find an answer to this, but I could not. Could anyone tell me how to change the elevation value of DEM? The one I have has been ...
3
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1answer
258 views

What are the X Units for an elevation profile and how can I change them to meters?

The question: How do I get a simple elevation profile for a line using QGIS 3.4 with height/distance in either meters or feet? The problem: I have the same problem using both Profile Tool and qProf ...
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2answers
72 views

Selecting based on distance and change in elevation

I am trying to find areas near a series of roads that are withing 500 ft of the road, and have a change in elevation of +50 ft. I have been provided a 2 ft contour of the area, and a centerline layer ...
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1answer
3k 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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2answers
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Computing the elevation angle of a GPS satellite with respect to the given receiver location

can anyone source an explicit formula for calculating the elevation angle for a GPS satellite as seen from a receiver. I can't seem to find one. Even a text reference would be great. I couldn't quite ...
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3answers
5k views

Obtain all elevations points from a raster DEM

I need to obtain all elevation grid points from a raster DEM. I see the steps required as: Read in raster DEM (Arc Info Binary Grid format). Create subset area using Points2One (see triangle area ...
3
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2answers
6k views

extract elevation values along a line using Google Elevation API

I note that there is the Google Elevation API. I see they have an example at the bottom showing an elevation profile for a line. Is there a premade service someone has put up on a website for me to ...
3
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1answer
391 views

Python: Convert DEM to 3D array organized as [lat, long, elevation]

I'm trying to convert a .tiff DEM to a numpy array using python. Ideally the array will store latitude, longitude (or some coordinate alternative), elevation). I'm using Gdal but currently it only ...
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2answers
1k views

Plotting and analyzing extracted elevation data in R?

I have a shapefile of county boundaries for New York state and elevation data downloaded through the elevatr package. library(elevatr) library(raster) library(sf) library(USAboundaries) counties <...
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1answer
279 views

Extracting only elevation data from NASA's GLAS Satellite LiDAR to create raster DEM?

I'm trying to open data downloaded from NASA's Earthdata site in ArcGIS 10.4.1. Specifically I'm trying to open "GLAS/ICESat L2 Global Land Surface Altimetry Data (HDF5) V034" (Image below, ...
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1answer
136 views

Assigning elevation to reclassified raster in ArcScene or ArcMap

How it it possible to make a 3D view of reclassifed raster map in ArcScene or ArcMap? I have identified a potenial avalanche area using DEM in ArcMap and now I want to have this map in a 3D view in ...
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3answers
1k views

How to quickly download all GMTED2010 data?

Is there a way to automatically download all the tiles in GMTED2010 data? From: https://topotools.cr.usgs.gov/GMTED_viewer/viewer.htm I can only seem to be able to download by double-clicking tile ...
3
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1answer
362 views

ArcGIS: how to obtain an average elevation for grid squares superimposed on a DEM? [duplicate]

Given the DEM of a certain Country, and a fishnet that is superimposed on it, I need to compute the average elevation and slope corresponding to each square in the fishnet. [I am using ArcGIS 10.3.1, ...
3
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1answer
121 views

What function should I use to assess the degree of elevational change (rocky cliffs etc.) of a DEM?

I have a DEM of my research area and I want to assess how the topography/elevation changes. I am specifically looking to see what areas may be good suitable bat-roosting habitat so I am trying to ...
3
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1answer
39 views

Enrich a featurecollection with more data

I have generated a vector feature collection which is great but I would like to add to this data before saving it out as a CSV. So the data is areas of forest loss in the county of Gwent and I want to ...
3
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1answer
165 views

How do I bring the Z value to attribute table?

I have a shapefile exported from a hydraulics software that I use. The file is exported as polylines. I convert it to a point layer using the "Extract Nodes" function. The remaining piece of ...
3
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1answer
63 views

Copy elevation from points to line

I have a vector line, but it has no z-dimension. I have some points along the line, which have the elevation included. Can I add the elevation from the points to the line at that specific point? ...
3
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1answer
316 views

Elevation profile from existing lines

I am trying to pass the geometry of a polyline from a map service layer to the elevation profile widget. Normally, when using a polyline generated from the Draw tool, we can grab the event geometry ...
3
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1answer
256 views

OSM Perspective View for Android/iOS

I am recently working on a project where i want to show a skiarea in a perspective view, like you know it from maps of skiresorts where the ski lifts are displayed. Are there any libraries where i can ...
3
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1answer
190 views

Convert DEM elevation points from centimeters to meters

I would like to convert a large DEM stored in PostGIS which contains elevation values in centimeters to elevation in meters. I found an easy way by updating each point like this: UPDATE mydem a SET ...
3
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1answer
323 views

Counting pixels on raster image

I have a raster file that show forest cover, very simple, where there is a green pixel there is forest. I need to count how many of this pixels fall under a certain elevation. I have the elevation ...
3
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1answer
3k views

Terrain() function for computing slope and aspect from elevation data always returns NA

I'm facing a problem with the terrain() function in the raster package (in R) since yesterday. I'm working with elevation data and coordinates in Lambert 72 (espg registry : "+init=epsg:31300"). Here ...
3
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1answer
390 views

Elevation profile using linear shape in ArcGIS Desktop?

I'm working with ArcMap 10.2. So, it's not a duplicate of "Displaying elevation profile and storing DEM elevation back to KML line using QGIS?". I have a linear shapefile that has only one element (a ...
3
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2answers
123 views

Exporting grid line nodes with ELEV attributes as data frame? [closed]

I would like to have a data frame of nrow x ncol where nrow = rows of my grid lines and ncol = col of my grid lines. The purpose is to use the ELEV data for 3D topography modeling in R. This is what ...
3
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2answers
994 views

How to find elevation highest and lowest for a state or city

I am trying to find out the highest and lowest elevation for these types of geographical areas: continent (lots of ways to get info) country (lots of ways to get info) state (for the US states no ...
3
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2answers
106 views

Making simple line more complex using QGIS? [closed]

I am trying to make my own version of code to generate elevation profile for a line drawn over a DEM and I got stuck very early on. As a simple use case: I have a line that consists of just two ...
3
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1answer
1k views

Performing viewshed analysis with Dutch AHN files in QGIS?

i downloaded the new (dutch hight data) AHN files, and was trying to perform a viewshed analysis at some point near UTRECHT. The plugin (grass plugin) works ok, i tried it before with a dem map. ...
3
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1answer
142 views

Looking for smallish raster of global elevation data

I'm trying to find elevation data for the whole globe for a simple mapping application and I'm not having any luck. I really don't want anything fancy, just something like a 4000x2000 raster of ...
3
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1answer
3k views

Extracting elevation data using Google Earth?

How do I extract multiple elevation values for a particular area in Google-Earth all at once? I've only been able to manually pick them one by one when I enter the long. and lat. for each point.
3
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1answer
7k views

How to convert to Australian Height Datum from Google Earth elevation?

I am trying to figure out how to convert from Google Earth elevation to Australian Height Datum (AHD). Google Earth's elevation / altitude is based on The vertical component (altitude) is measured ...
3
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2answers
2k views

Add Surface Information in 3d-analyst

One of our guys is using the "Functional Surface->Add Surface Information" feature in 3D-analyst tool in ArcMap 10.1 to add elevation data to an XY list. It's the only feature we're using from the 3D-...
3
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1answer
277 views

Show elevation profile from linestring's z values

I have linestring geometries with z values and I want to display them in a nice elevation profile (with x/z scaling functions, several profiles to overlay, and so on). Is there any QGIS function or ...
3
votes
1answer
117 views

Including elevation values in polyline (to export it as ASCII table)?

I'm using a code to simulate flood events and I need to build two main files: one with the river channel width and another one with the bed elevation (both in ARC-info ascii raster format). I've ...
3
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1answer
314 views

Postgis Self-intersection on geometry<->raster comparison

I am rather new to postgis and try to get a (weighted) average height of an area around a point. I am running Postgresql 9.5.5 with Postgis 2.2.1 on Ubuntu. I have imported ASTER GDEM elevation ...
3
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2answers
164 views

GeoTiff Elevation Service

Is there a standardized web feature (WFS) or web processing query to get a single pixel value from a map? I don't need a whole tile, which seems to be what the WFS and WMS standards are designed for....
3
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1answer
836 views

Reading 1/3 arcsecond DEM data using C++?

I am writing my own application to use and present elevation data. So far, I've been easily using the three arc second SRTM data presented in ArcInfo ASCII format. But now I'm looking to use the ...
3
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2answers
554 views

Find elevation for series of (lat,lon) combinations to make 3d model of earth with relief

I would like to say I am a complete novice to the world of GIS, so if I ask stupid questions or make strange assumptions, please point it out and I will try to clarify myself. I would like to make a ...
3
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2answers
310 views

How do I get rid of this thin band between raster layers created from TNM?

After hitting my head against the table for many days, I'm humbly presenting myself to the QGIS community. I downloaded 4 IMG files (1/3 arc second, elevation data) from The National Map on the USGS ...
3
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1answer
137 views

Elevation off Road in ArcGIS/Python

i'm using the Modelbuilder in ArcGIS 10.1 to calculate pixels depending on their slope and distance from the road. The third necessary task is to find out, if the pixel is upwards the road or ...

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