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

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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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152 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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149 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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69 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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108 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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314 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 ...
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401 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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555 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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513 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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275 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 ...