Questions tagged [elevation]

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

Filter by
Sorted by
Tagged with
5
votes
1answer
683 views

How to find all points with certain elevation difference between them in QGIS

I have a point layer (xyz) and want to find all points that have elevation difference of 200m or more. I would like to then draw a line between each pair with the largest elevation difference. The ...
5
votes
2answers
4k views

How to read GeoTIFF using PHP?

My current pet project involves creating a web service that uses the CGIAR SRTM worldwide elevation data set. Each request to the service will query for elevation data from a small geographic area. ...
5
votes
1answer
998 views

Find lakes on an elevation raster

I would like to know if there is a way to identify lakes based on an elevation raster (like SRTM or ASTER)? As far as I can understand, it would mean identifying any cell below the elevation of ...
5
votes
1answer
634 views

Identifying south facing mountain land, above an elevation, within a slope range, less than fixed distance from major roadways

This odd question comes from believing that such an analysis is plausible in a GIS system. Only, I don't how to accomplish the various discrete steps implied from the Title, nor where to get a topo ...
5
votes
1answer
178 views

QGIS: Edit elevation in DTM to get correct slope of a river

I am new to QGIS and just need it to do a hydrolocic analysis of an area of which I later make a flow model with HEC-RAS 2D. I made it according to this tutorial: https://www.youtube.com/watch?v=Ro-...
5
votes
1answer
177 views

Update from/to Z from attributes using arcpy Update Cursor

Trying to update Z values onto some point and line features from the level attributes on each feature. My script works fine on points - the previous Z values of 0 now have the same values as the ...
5
votes
1answer
277 views

Creating a point corresponding to the maximum elevation of a DEM [duplicate]

I am wondering how can I create a point corresponding to the maximum elevation value of a DEM. I mean, from the DEM I can easily get the maximum elevation. For the sake of a viewshed analysis, I would ...
5
votes
3answers
1k views

Using Focal Statistics to calculate saddle points from DEM in ArcPy?

I have a conundrum with Focal Statistics and kernel files. I am been trying to identify saddle points in DEMs. I am attempting to rewrite this (thanks whuber) in a python script for 10.1. I have ...
5
votes
2answers
2k views

How to determine the most accurate elevation algorithm

I use an Android GPS cycling app to track my bike rides and I would like to get a reasonably accurate estimate of the total ascent I did on a ride. I understand that GPS is very inaccurate at ...
5
votes
1answer
235 views

Cartographic technique for detailing a 'Focus Area'

I'm working on updating a planning document. Whoever was in charge of cartography last time around used a great technique to identify and showcase focus areas (where to focus money and effort for ...
5
votes
1answer
854 views

Interpolate temperature data (shapefile) using R

The answer below solved my fist question, so I edit my question as follows: I have a shapefile given with the attributes lat, lon, elevation and temperature. So far I have a script that interpolates ...
5
votes
1answer
87 views

Reconciling elevation difference between SRTM and old US Army map in Laos?

In QGIS I georeferenced a 1970 US Army contour map for part of southern Laos (20 m intervals) with the following indicated properties: Horizontal datum Indian datum 1960 Spheroid=Everest Verical ...
5
votes
2answers
5k views

Does Google Maps Elevation contain buildings, trees, and other structures?

Does anyone know whether Google Maps Elevation data removed buildings, trees and other non-terrain related structures from its elevation data? I checked their pages, but couldn't find an answer to ...
5
votes
2answers
3k views

Generate TIN from elevation data in Python (no Arc)

I would like to generate a 3d terrain model of an area, and I am stuck on creating the TIN (which I will convert to an STL). I know there are plenty of ways to use ArcGIS, QGIS, 3DEM, and various ...
5
votes
2answers
735 views

How to query DEM elevation values in a web application based on cursor/click point location?

I work for a city government that has LiDAR derived DEM rasters which we would like to make accessible to other departments in the city. The problem is that many departments don't have anyone with ...
5
votes
1answer
1k views

How can I get the average elevation for an area in QGIS?

I have got .tif file for a country and a dbf file which divides the country area into 42 subunit. I want to get the average elevation data for each subunit in meters.
5
votes
5answers
2k views

Google Earth Polygon surface area to follow the curvature of the earth model

Question: When drawing a polygon in Google Earth with latitude, longitude and elevation values at each node, how do you ensure that the surface area of the polygon also represents the desired ...
4
votes
5answers
2k views

Elevation correction ASTER GDEM2 (+10m)

My ASTER GDEM2 has a average elevation error of -10m for my area. (I testet it using 90 defferential GPS reference points and compared it with old Topo25, SRTM, and GoogleMaps). I would like to ...
4
votes
6answers
4k views

shadow simulation from buildings [duplicate]

is it possible to use hillshade function in ArcMap to calculate shadow areas of buildings or simulate shadows of buildings, using DSM of the buildings and the sun angle and azimuth?
4
votes
3answers
2k views

Get rivers from a DEM raster

I am new to spatial analysis and even newer to hydrology. I have a 30arc DEM elevation raster and I was wondering if I can use it as an input to get the approximate presence of rivers in a ...
4
votes
2answers
4k views

Inaccurate altitude GPS data with my Android?

I've been recording tracks with GeoTracker on my Android. In places I have points that have altitudes higher than the peaks of a mountain. Like one altitude difference is 46 m. How is it possible to ...
4
votes
2answers
1k views

Subtracting out slope (in general) of DEM using ArcGIS for Desktop?

I'm searching for a solution process to subtract out the slope of a DEM like this: I have a high resolution DEM and want to reconstruct historical/old/not active parts of a river. The problem is the ...
4
votes
3answers
1k views

How to get the elevation of the areas in a raster file from SRTM?

I have an SRTM elevation map. How do I get the elevation of each point in the map? I am using GRASS. Is there a GRASS script to do such?
4
votes
2answers
859 views

Kriging values greater than the most extreme value of the input layer?

I'll admit I don't understand kriging to the fullest. Yet, I've read that the weights should add up to 1 as in IDW and Natural Neighbors. However, surrounding the biggest elevation points of my ...
4
votes
1answer
240 views

GTOPO30 elevation value are wrong in QGIS

I downloaded GTOPO30 DEM archives from USGS(earthexplorer.usgs.gov/), and I just simply drag the file into QGIS, but somehow I find the elevation isn't the same with the actual scenery. I want to draw ...
4
votes
2answers
814 views

Looking for the simplest way to get elevation for a give wgs84 coordinate

I started a project and write an application in java using geotools. I have an simple geoobject with the attributes latitude, longitude and altitude. Now i have to determine, wheather the geoobject is ...
4
votes
1answer
3k views

How to obtain a DTM/DEM from DSM

I need to obtain a grid of bare ground elevation (removing all edifices, trees, roads and man-made elements) for quantitative geomorphological analysis from a high resolution (1 m) DSM obtained by ...
4
votes
1answer
2k views

Set the minimum and maximum values for an elevation raster in R

I have a raster that displays elevational values at a global scale. I would like to set the minimum and maximum values based on the values I would like to choose. > elev class : RasterLayer ...
4
votes
1answer
805 views

Converting elevations into correct units with pyproj?

I am converting a point from wgs84 into a state plane coord system (epsg: 32051, which is defined in US survey feet) using pyproj, but the transform isn't changing the z values into feet: point_4326 =...
4
votes
1answer
2k views

How to give elevation information to a polygon feature class using existing TIN file ? (geological mapping)

I'm an ArcGIS 10.1 user. My issue: I have a printed form of a map which depicts geological bodies being surface rock occurence. Additionaly, there are elevation contour lines. I digitized the map by ...
4
votes
2answers
247 views

How do I calculate the Terrain Ruggedness Index for each county in the United States in R?

I have a shapefile of US counties and high-resolution elevation data that spans the entire contiguous United States. My goal is to calculate a terrain ruggedness index for each county. The functions (...
4
votes
1answer
776 views

Command line tools to generate elevation profile from DEM + GPX/GeoJSON

I'm looking to generate elevation profiles from a number of GPX traces (which I also have GeoJSON conversions of). I have 20m resolution DEMs of the area, in GeoTIFF format. Ultimately I want to ...
4
votes
2answers
560 views

Huge x,y,z dataset into oracle, possible?

I have 200 .xyz files containing 1500000 points each. Is this possible to import this dataset to oracle? It makes a total of 300.000.000 points!!! Background is I want to improve a FME script that ...
4
votes
1answer
2k views

How to get elevation with LibGeoTiff?

I'm trying to get an elevation profile from a geotif file ( downloaded from http://srtm.csi.cgiar.org/). I downloaded the libgeotiff library but i can's see any function that can return an elevation ...
4
votes
2answers
2k views

Converting Geocentric to Geodetic

I am only looking for a confirmation of what I believe to be true. If my explaination or conclusion is not accurate I would appreciate it if the reason can be explained to me. Background Information:...
4
votes
1answer
81 views

Can QGIS produce a Stage Storage Plan?

I work for an engineering firm, and my question to the forum is: Can QGIS produce a stage storage plan for multiple drainage basins? I am attaching an image of what I am talking about. Currently, we ...
4
votes
2answers
545 views

Extracting peaks from DEM and creating 5 m elevation buffer around each peak in ArcGIS Desktop?

I have a DEM available and would like to identify all the peaks that are likely to be bare rock. I want to be able to isolate these areas and create a 5m elevation buffer around them to represent the ...
4
votes
2answers
338 views

How to form a V-Shape field of view from any given point (i.e. latitude longitude)

I want to visualize the V-Shape polygon which can be referred to field of view as well. So, far i have been able to find the latitude and longitude of a certain point when i give an input of latitude ...
4
votes
1answer
2k views

How to create an elevation profile in google earth from a kml?

I have a KML file of a stream that I originally created as a line shapefile in ArcMap (one stream extracted from a larger watershed data set). I need to create an elevation profile of this stream. ...
4
votes
1answer
576 views

How to map flood areas from a set of points containing surface and height of water?

I am working on the damages made by the typhoon Haiyan. I use QGIS 2.0 with extensions and toolbox, and MapInfo. I have vectors, rasters of the place. I want to map the flood area along the ...
4
votes
1answer
1k views

What functionality exists to calculate Cut and Fill for excavation?

Does qgis have the ability to compare and quantify existing versus proposed elevations?
4
votes
2answers
2k views

How to manually edit 16 bit GDEM elevation data on a Geotiff file

I'm building a virtual 3D terrain scenery using both satellite imagery (google maps satellite) and elevation data from GDEM Aster elevation data (geoTIFF format files). My problem is that the ...
4
votes
1answer
2k views

Elevation graph from GPX file

I've got many GPX files in the following format: <?xml version="1.0" encoding="utf-8"?> <gpx xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"...
4
votes
1answer
148 views

Use DEM elevation attributes in vector polygon?

I am modeling glacier retreat scatching polygons on DEM surface trying to come out with 3D scatch. Is it possible to adjust "height" of polygon to follow elevation of DEM surface (eg. glacier height ...
4
votes
0answers
509 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 ...
4
votes
1answer
290 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
votes
0answers
939 views

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 ...
3
votes
1answer
693 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, ...
3
votes
3answers
643 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). ...
3
votes
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 ...