The height of an object or point in relation to sea level or ground level.

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0answers
7 views

Add attribute column with road's altitude

I have some vector layers with a set of latitude and longitude coordinates.Is it possible to add a new column to the attributes table containing the altitudes of the road? (the data was collected ...
1
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0answers
14 views

Three dimensional Routing

I have created a route by hand using the Tracing Tool available in QGIS. I wanted to export all the coordinates to another program, so I saved them in a CSV file. The problem is that I can only see ...
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1answer
65 views

Extract height values from vector to CSV

I have generated a CSV file (using the MMQGIS plugin) expecting to obtain all the coordinates of a vector layer that I have created. But the output file only contains the latitude and longitude ...
-2
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0answers
15 views

distance and altitude difference betweeen two rasters

I have to different raster, both in 30 arcsec and WGS1984. One raster contents selected landcover and the other raster is a DGM. For each landcover cell I need the shortest distance in km to the ...
0
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0answers
10 views

MSL/AGL bounds checking in PostGIS for Line/Polygon Intersection

I have a table with Polygons and columns defining an optional upper and lower altitudes bounds and altitude type. The Type can be MSL, AGL, or NULL, if unbounded, and can be set separately for upper ...
2
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1answer
30 views

Get Altitude for Multiple Objects

I use QGIS and I has two layers: one with point objects (more than 1000) and one with surface (it is a version of DCW). I want compute altitude of all points. Basically, I want to get an array where ...
1
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0answers
25 views

Faulty altitude point between contours

I have point(picket?) between 2 contour lines with even number altitudes. Now i got these new 5 meters steps contour in between. As you see, this point between red lines was OK, but now that this 175 ...
4
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2answers
96 views

Map scale based on altitude

I'm either missing something or failing at some basic math here, but is it possible to calculate the map resolution (map units/pixel) based on altitude (from sea level)? I have center coordinates and ...
0
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1answer
2k views

“Update Altitude” does not work on TCX Converter

I have downloaded TCX Converter from the official site. Although I update altitude data of points which I created from Google Earth, they can't be displayed on table. Only "ml>" is written on ...
2
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1answer
50 views

How to LOLA DEM 16bit signed TIFF to QGIS Greyscale (BumpMap) image?

I have a moon 16bit signed TIFF downloaded to my computer from http://astrogeology.usgs.gov/search/details/Moon/LMMP/LOLA-derived/Lunar_LRO_LOLA_ClrShade_Global_128ppd_v04/cub A pointer please in ...
2
votes
1answer
300 views

Relation between Geoidal separation and antenna altitude in GGA sentence?

I have searched about definitions and relations about geoidal separation and antenna altitude reported in GGA sentence. The more I read the more I am confused.So in a simple manner can anyone explain ...
1
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0answers
45 views

How to include altitude using QGIS for field surveys capturing lat/long for utility locations?

I am using QGIS with a USB GPS to capture lat/long of utility locations. I have created a .csv file with a few fields e.g. address, cross st, id number, etc. and made it "editable". When I locate a ...
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0answers
97 views

Get the altitude for a given geo location with online OpenStreetmap

Is there a simple way to get the altitude for a given geo location? I would like to add a link to our gluon node form, that links to a place, where I can easily retreive the altitude above NHN or ...
2
votes
1answer
231 views

Reaching cm (inch) level elevation precision using drones

A road construction firm needs altitude data of road path before and after the construction and the error should be less than 3 cm (2 inch). Normally, they put a ground station and workers manually ...
1
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0answers
348 views

GLONASS speed and altitude limitations

I'm looking for some info about the possible limitations for the GLONASS navigation system, something similar to the GPS COCOM limits. Is there any limitation on speed AND/OR altitude for this ...
0
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0answers
56 views

Is there any application that gives the real absolute altitude?

I defined a test already and I would like to compare the altitudes measured by different sources. I drove a path by a car, mounted a GPS and a pressure sensor in the vehicle. On the chosen path, there ...
1
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0answers
212 views

Determine lat/lon intersection on earth from point in space along 3d line

I have a known point in space with a lat,lon,alt. It has a camera with a line of sight and a angle of field of view. I can take the central point and calculate each corner vector of the field of view, ...
1
vote
1answer
125 views

Creating an irregular points grid — one with regular along-slope distances [closed]

I am currently using QGIS to try and prepare a series of equally spaced -- along the terrain slopes -- sampling points within various NVC (National Vegetation Classification) sites in the UK. I am ...
1
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0answers
350 views

Setting the correct zoom level from Sector bounds for flat map using WorldWind SDK

This is not coming out correct for me. Setting the zoom level based on some other code I got on here using the EarthFlat model, which does not set the correct zoom for the placemarks within a sector ...
2
votes
0answers
291 views

SRTM elevation data question

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 ...
2
votes
4answers
2k views

Is there a way to get Z value from 3D multipoint shapefile in QGIS?

Is there a way to get Z value/height/altitude from 3D multipoint shapefile in QGIS? All I found is way through SpatiaLite or PostGIS as explained here: http://faunaliagis.wordpress.com/2013/08/14/...
0
votes
0answers
91 views

How to calculate raster distance with z value using ArcGIS for Desktop?

I'm trying to produce a raster distance map by using euclidean distance function having input feature as flight path (with altitude as Z value). However, my euclidean distance calculation did not ...
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1answer
601 views

How to calculate relative height of point on slope relative to nearest creek and ridge?

I'm attempting to calculate the relative height (values between 0 and 1 preferably) of waypoints on a slope along the path of least resistance. Ideally, points in creeks would have values of 0 and ...
1
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1answer
573 views

How can I add height data to a polyline in QGIS?

I want to place a polyline at the correct altitude in QGIS. Is that possible and how do I do this? What I have is a polyline (railroad) and I want to add information on the electrics above the ...
17
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4answers
825 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 ...
2
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0answers
227 views

Height of the geoid in ECEF coordinates

I know that the relationship of geoid height N and ellipsoid height h to orthometric height H is defined by H = h - N, but what if I have some position in Earth-Centered-Earth-Fixed (ECEF) coordinates?...
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0answers
1k views

Calculating Accurate % Grade from GPS Coordinates

I am trying to calculate % Grade from GPS points. I am using the basic equation of (Rise/Run)×100 The problem is I am getting spikes in my GPS data (example 1 meter rise for 3 meter run), I am ...
12
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2answers
681 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 ...
3
votes
1answer
1k 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 ...
6
votes
2answers
1k views

How to get latitude, longitude and altitude database from a GeoTIFF file?

I am developing an AR iOS application. When the iPhone gets the current location, it has to calculate locally the visible point. I want to read the tiff files in my application, and then get the ...
11
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2answers
1k views

What is my distance when viewing a scaled-topographic map?

A close friend from my company asked me a question about a topographic scaled map (1:25.000) that what was the altitude to a location in km (as you are viewing Earth from space) when he was viewing ...