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

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-1
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1answer
21 views

How to decrease elevation values of DEM using open source GIS sotware? [on hold]

I am newbie in QGIS, but I was wondering how to decrease elevation dem DEM using QGIS? Can QGIS do that? Or anyone of you can tell me any open source GIS software to perform that?
1
vote
1answer
166 views

Using GDAL to read dted files

How do I get the elevation at a certain point using gdal to read in a dted file? I don't see much useful information out on the web. I'm sorry I should have been more specific. How would I ...
2
votes
1answer
743 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 ...
0
votes
0answers
16 views

Where can I download 1/9 arc-second elevation data for the Hawaiian islands?

In same spirit as this question, I'd like to know where I can find 1/9 arc-second elevation data for the Hawaiian islands. The USGS national viewer provides 1/9 arc-second data for certain places, ...
1
vote
3answers
2k views

Downloading 1 arc-second elevation data for Canada other than Geobase?

Can someone suggest a source for Canadian elevation data better or equivalent to 1 arc-second? I have a good data source for Ontario but for other provinces folks often recommend Geobase which claims ...
3
votes
1answer
112 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 ...
0
votes
1answer
637 views

How do I add elevation data to a GeoJSON line from a GPX file?

I understand that elevation can be added as an optional third value in Coordinates (lat, long, elev) in a geojson file, but I can't find a way to actually do that from a gpx file. I've used ogr2ogr to ...
4
votes
1answer
92 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 ...
3
votes
1answer
85 views

How to subtract out the slope (in general) of a DEM?

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 ...
2
votes
1answer
257 views

How to change layer transparency without changing border lines?

I have a raster image of elevations. I have added a vector shapefile that contains local political divisions. I want to keep the elevation colors, but I want to keep the black lines representing the ...
7
votes
1answer
439 views

Bringing GIS data into Minecraft

A little off the beaten path...: Denmark has built a 1m:1block Minecraft World using real GIS data. Here's the home page, in Danish: http://gst.dk/emner/frie-data/minecraft/, and an ArsTechnica ...
12
votes
2answers
449 views

Why does GPS altitude jump sometimes?

I am currently developing a little application in Android which uses GPS. When i click a button i start to record a "track". If i walk around i save my position every second into a file. This works ...
16
votes
4answers
299 views

How is elevation and altitude measured?

According to my watch that claims to measure altitude, as far as I can see it says that in Stockholm Sweden the altitude is 170 meters but can that be right? How exactly can we know that 0 altitude in ...
0
votes
1answer
121 views

How to select a subset of a DEM in ArcScene?

I'm using ArcGIS 10.0 and trying to open a digital elevation model in ArcScene. I'm working on a project and got the DEM data from official sources which is quite huge. The resolution of the DEM is 1 ...
0
votes
1answer
20 views

Want to intersect a polygon of a certain elevation with a tin surface

so I want to generate a flood plain for a river in ArcMap. Basically this means that I want to create polygons with certain elevations above the drainage point elevation (870 m). For instance I would ...
0
votes
1answer
24 views

Web site to show GPX with elevation?

I notice that a GPX file contains not only lat + lon but also elevations: <trk> <name>Some route</name> <trkseg> <trkpt lat="50.64536" lon="3.05657"> ...
8
votes
4answers
2k views

Elevation profile 10 km each side of a line

How can I get an elevation profile for a band of terrain? The highest elevation within 10 km (on each side of the defined line) should be taken into account. I hope my question is clear. Thank you ...
0
votes
1answer
36 views

How to get the z(elevation) value from a rendered map at webgl(Qgis2threejs plug-in)?

I am interested at getting the z value at any lat and long i want. For example i have made a 3D map using Qgis2threejs plug-in and it showed the map rendered using three.js library. The elevation ...
1
vote
1answer
55 views

Learning about bathymetry?

Besides reading about bathymetry, I would like to work on some hands-on training that I can learn about bathymetry. Is there any good bathymetry out there that I can get some training with the ...
1
vote
0answers
16 views

QGIS Extract elevation data only for one country [duplicate]

Hye, Here a map built with (1) a shape file for country contour, and (2) raster from .hgt files with altitudinal representation. How can I only select the area corresponding to the country ? I found ...
2
votes
2answers
69 views

Check if a polygon is at one elevation

I have a polygon (pond) and I need to ensure it is at one elevation. I have converted all vertices of the polygon to points, used summary statistics to determine the range in elevations and if the ...
1
vote
0answers
36 views

River flow downhill

I have polylines (rivers) with assigned elevations. I need to ensure they are flowing downstream and indicate which vertices are incorrect. I do not have 3D analyst, spatial analyst, or network ...
6
votes
1answer
77 views

What resampling technique should be used to reproject an altitude raster?

Does anyone know whether I should choose: nearest, bilinear, cubic or majority when projecting the WorldClim altitude raster layer?
3
votes
2answers
68 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 ...
1
vote
1answer
46 views

Select points with lowest elevations and same x,y coordinates

The problem is as following, I have a point layer with x,y,z coordinates. Some of the points have same x,y but different z. I need to separate points without duplicates (x,y) and in case there are ...
1
vote
2answers
55 views

Interpolate dxf polyline vertex elevation from DTM?

I am working on several autocad polylines (with several vertices...) that have the exact N,E coords but now I would like to add the elevation data for every polyline's vertices from a dtm. I thought ...
24
votes
7answers
10k views

What is the best 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 ...
2
votes
0answers
29 views

infer the altitude from a DTM & finally provide it to point / evincere la altitudine da un DTM & finalmente fornirla a dei punti

I would like to complete a point vector's table with Z data. I am not able to take Z coordinate from a dtm (downloaded from ...
2
votes
1answer
68 views

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 ...
2
votes
1answer
28 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 ...
2
votes
0answers
76 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 ...
3
votes
0answers
23 views

How can ASTER elevation data be converted to a CAD model

I am trying to convert ASTER elevation data to a 3D CAD model using only opensource software. I have tried using different file formats but I have been unsuccessful. I use QGIS for my GIS work and ...
4
votes
2answers
2k 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. ...
4
votes
1answer
139 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 ...
2
votes
0answers
46 views

Find Average Elevation - ArcGIS Desktop

I am working with 2 shapefiles. One contains the boundaries of a city, the other contains polylines representing the topographic features of the area. Essentially, the polylines make a topographic ...
2
votes
1answer
20 views

Grass, Route Finding with Elevation Limits

I've got GRASS (7.0) installed and I "play" with it on ocassion since I am far from a GIS pro. What I want to do is to find all road routes from a certain point limited by distance (path length, not ...
10
votes
5answers
6k views

How to calculate Topographic Ruggedness Index in Arcgis?

Does anyone know how to calculate Topographic Ruggedness Index in Arcgis without access to command line arcinfo workstation? "The topographic ruggedness index (TRI) is a measurement developed by ...
2
votes
0answers
28 views

Project lines onto surface in QGIS

This question may already be answered so please point me in the right direction. I am designing a water distribution system for a rural village in Guatemala. I have created contours for the area. I ...
3
votes
0answers
54 views

Where do I find official summit elevations found on USGS topo maps?

I'm creating topo maps for my day hikes guides for national parks. I've already done one for Glacier National Park. When I was working on summits, I downloaded the data for Montana from GNIS and when ...
1
vote
0answers
49 views

Inverting color ramp in legend

I have inverted the color ramp to display land surface elevation, now when I add a legend in print composer it shows the lowest value at the top and the highest at the bottom. See below: It is more ...
1
vote
0answers
19 views

How to merge elevation from a raster image onto a shape road network with QGIS? [duplicate]

I have a shape file with Stockholms road network and a raster image with elevation data from the same area. Is there any way to merge the two somehow, either by adding the slope direction as ...
0
votes
0answers
45 views

How to calculate fastest bicycle routes in Stockholm with QGIS?

Hello StackExchangers, I would really appreciate if expert users could point out a few directions for me, this is what I wanna do: Access an online map from my iPhone that gives me the possibility ...
14
votes
4answers
5k views

Where to download free elevation data for Europe?

Where can I find free elevation data for Europe? Please mention the available resolutions and terms of use when posting a source.
3
votes
0answers
295 views

How to extract elevation data 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.
6
votes
2answers
120 views

Reducing elevation from DEM using ArcGIS for Desktop?

I am so curious how would I strip off elevation from the DEM. I don't know how I would explain it further but I have attached an image to clarify this. I wanted to eliminate the area shaded with ...
2
votes
1answer
109 views

shapefile to gmt format

I have an ESRI shapefile of the contours of my study area, and I want to convert it into a format that is acceptable by GMT, so I can make an elevation map of my study area. Is that even possible? ...
2
votes
0answers
61 views

Can I use the Google Elevation API for academic research (licensing)?

I would like to use the Google Elevation API to generate about 5 elevation maps for master's degree research on aircraft collision avoidance. The data would be meshed and used in simulation to ...
2
votes
0answers
81 views

best method for gridding or interpolating elevation data

I wonder if someone can recommend the best method for gridding elevation data in QGIS, GRASS or similar. The elevation data I have is collected along 1m spaced lines at approximately 1 reading per ...
2
votes
1answer
395 views

How to create contour lines from point data?

I'm using QGIS 2.4.0 and I have a shapefile of points with elevation data and X and Y coordinates. I'm using windows 7 OS. The idea is to create a contour line SHP using my point data. My question ...
1
vote
1answer
96 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 ...