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

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23 views

Google Earth/KML colors of polygons darken when extruded

I'm playing around with KML, trying to create a multivariate map with a choropleth based on one variable and extrusion/perspective height based on another. Here is an example of a Google Earth image ...
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54 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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35 views

True Altitude of GPS cooridnates

Given two points a=(lat1, long1) , b=(lat2, long2). I want to divide the line between a and b into points with equidistant length. (for example 100 Points) For each of these points i need to ...
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0answers
36 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 ...
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0answers
51 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
76 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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0answers
169 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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0answers
119 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 ...
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2answers
652 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: ...
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0answers
67 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
325 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
281 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
328 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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0answers
148 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) ...
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0answers
594 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
500 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
886 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
765 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
588 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 ...