Questions tagged [altitude]

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

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27 views

OpenLayers: find out the units of height value

Is it possible in OpenLayers to find out (ideally from ol/proj/Projection or from ol/source/Source), what is the Unit of Measurement for height (z-coordinate)? Or is it possible to assure somehow, ...
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45 views

Altitude differences in different CRS

Currently I am working on a project in Kosovo. After gaining autonomy the country "invented" their own CRS, which is driving me crazy sometimes. It doesn't even have an EPSG-Code, it goes by "Kosova ...
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86 views

Adding Altitude to a marker in WebGLEarth

Im trying to add an altitude to a marker in WebGLEarth but i cant figure out how to do it. I cannot find anything in documentation either. The idea is that my markers act as satellites so i need the ...
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Qneat3 / shortest distance calc sensitive to altitude?

I'm trying to calculate shortest distance using Qneat3 (using both the shortest path and OD-matrices for different purposes). And am wondering if there is any possobility to factor in altitide (it is ...
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47 views

Convert MSL to WGS height

I need to find the coordinates for a given location in WGS coordinates. This mean geodetic latitude, longitude, and altitude (with respect to the reference ellipsoid). I was informed the coordinates, ...
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1answer
50 views

Focal length vs Principal point

I have set of areal imagery. One of a parameters I get with images is camera's Principal Distance , what I'm looking for is Focal length, but I don't have Focal length at the moment I tried to ...
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51 views

KML: Making all points on a polygon relative to ground by same amount?

I need to generate large polygons that are all on the same plane but are all some relative distance from the ground. I need to do this without knowing what the absolute altitude is. So imagine I am ...
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1answer
183 views

How to plot a point on the highest elevation of a raster on a polygon. QGIS

I have a shp with more than 1700 polygons on a elevation raster. I need to plot a point that represents the highest altitude location within the polygons, and then export those points as a new shp.
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32 views

Why is my aspect not displaying the full data?

I am trying to get the slope aspect for the altitude shown above. Can someone please advise me on why this may not be working properly?
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1answer
383 views

Is kml altitude mode “absolute” equivalent to altitude over WGS84 ellipsoid?

I am working with an aviation software which outputs points with altitudes over WGS84 ellipsoid. Now I want to represent those points in Google Earth, writing a kml file. I know I have to convert the ...
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172 views

GPS Altitude uncertainty and postional uncertainty in Lat/Long [closed]

I'm working on flight sensors for a project and I'm supposed to model GPS device noise. I looked a lot for it online and could not get a convincing answer. I need the uncertainties of altitude and ...
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Choosing datatype for holding Latitude, Longitude and Altitude in PostGIS?

I'm trying to take advantage of the many functions available in Postgis for dealing with latitude and longitude coordinate systems. However, I would like to add some altitude information to my ...
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ISA Model and GFS data

I have a newbie question... I always used the International Standard Atmosphere model whenever I needed to calculate the temperature in a given altitude. It always looked accurate to me... However,...
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726 views

Correcting incorrect altitudes of points recorded by my Android or how to calculate Geoid Height in QGIS

I tried to edit my question with more details and I also think that lot of people can benefit from this question! I was recording a track with my Android and later I found out that I end up having ...
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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 ...
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151 views

Does Magnetic Deviation depend on altitude? [closed]

Magnetic declination, sometimes called magnetic variation, is the angle between magnetic north and true north. Declination is positive east of true north and negative when west. Magnetic ...
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953 views

Height above sea level measurement

I would like to use height above sea level in the gravity equations. What is the source for getting it? Can i use altitude measurements from Altimeter or GPS 'z' measurement? For your kind information,...
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115 views

Calculating highest point, lowest point, average altitude in specified area around click position in Cesium? [closed]

I have successfully computed the height of a location where user clicks in cesium but my next step is a bit complex. What I want to do is that when user clicks at some point on globe, at any zoom ...
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2answers
105 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 ...
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45 views

Use of Airbus WorldDem altimetric values (EGM2008)

In France, the altimetric values are issued from a mesure of heights above the sea level based on the Marseille's tide gauge. If i didn't mess it up, the system is named NGF - IGN69 for mainland (See ...
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1answer
257 views

QGIS: Show line ELEV on hover or select?

I've installed the value tool plugin, but cannot figure out where it outputs. I tried map tips in qgis. How can I see the elevation of a line or selected point on hover or select?
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1answer
168 views

Is elevation (height relative to sea level) constant, despite sea level rising?

Is a 10,000' peak still a 10,000' peak if sea levels have risen a foot? Is it a 9,999' peak now, or is elevation just a constant? Seems odd that a patch of land a few feet above "sea level" could sit ...
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77 views

Three-Dimensional Routing

I have created a route by hand using the Tracing Tool available in QGIS, placing the waypoint on top of an Open Street Map layer. I wanted to export all the coordinates to another program, so I saved ...
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1answer
313 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 ...
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1answer
174 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 ...
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33 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 ...
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2answers
382 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 ...
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1answer
17k 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 ...
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1answer
265 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 the ...
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3answers
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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 ...
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206 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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4answers
1k 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 ...
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1k 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 ...
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1k 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, ...
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1answer
229 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 ...
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668 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 ...
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933 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 ...
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4answers
5k 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/...
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1answer
1k 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 ...
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1answer
1k 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 ...
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4answers
14k 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 ...
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411 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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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 ...
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2answers
1k 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 ...
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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 ...
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2answers
2k 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 ...
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2k 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 ...