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

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23
votes
7answers
9k 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 ...
15
votes
3answers
5k views

How to download the entire ASTER GDEMv2 dataset?

On October, NASA released the new ASTER GDEM global dataset (30m) and I have been wanting to get my hands on it. The only problem is that it takes forever to download and I do not feel like drawing ...
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.
12
votes
5answers
6k views

How to get an elevation profile for a gps track?

I'd like to get a reasonably accurate elevation profile for a track recorded with a GPS (which often has very unreliable altitude data and occasionally none at all, depending on the model.) Does ...
11
votes
3answers
198 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 ...
11
votes
1answer
429 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 ...
11
votes
3answers
964 views

Distribution of Human Population with Altitude

I recently found Joel E. Cohen and Christopher Small's work on hypsographic demography, i.e. the distribution of human population with altitude. Does anyone know of any other research in this area? I ...
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 ...
9
votes
4answers
3k views

Code to calculate elevation profile along line from a DEM

Given a DEM (Digital Elevation Model) say in and a line (x1,y1) --> (x2,y2) (paired coordinates (x,y)), how can one calculate the elevation profile or cross-section projected on that line ? I am ...
9
votes
3answers
885 views

What are common methods for converting raster digital elevation data to vector contours?

In researching this I have found many references to the opposite, creating elevation data from contours, but nothing regarding contour creation. Preferably, I am looking for open source solutions like ...
8
votes
2answers
744 views

DEM Elevation Units

I'm fairly new to the GIS world, and have a quick question. I'm currently using 10.1. I do not know much about rasters, so does transforming a DEM from one projection to another automatically convert ...
8
votes
2answers
623 views

Elevation profile sample point algorithm

In generating an elevation profile, samples from the underlying raster must be taken. If the objective is to create a profile of maximum quality, how should the locations of sample points be ...
8
votes
2answers
852 views

What is the smallest contour interval possible when derived from a DTM?

I am converting a 2m DTM to contours, and would like to have the smallest interval possible. Is there a theoretical limit, or even a rule of thumb for defining contour intervals based on the ...
8
votes
7answers
908 views

seeking “Available Sky” implementations

I'm looking for implementations of an algorithm called "Available Sky". ArcGIS (Spatial Analyst or GRID) is preferred, but solutions in GDAL, SAGA GIS or others are perfectly acceptable. The ...
8
votes
1answer
415 views

How to generate a DEM from isolines and spot heights?

I have two shape files containing height information of a certain area and I need to create a raster DEM with GRASS using them. file 1 consists of height information in contours (isolines) file 2 ...
8
votes
1answer
880 views

PostGIS - Calculate progressive distance between points on a GPX path

I am attempting to build an elevation profile using PostGIS-PostgreSQL only. I have imported GPX data in my PostGis database, so now I have a table full of the GPS coordinates of the track and the ...
7
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 ...
7
votes
5answers
1k views

Is there an online tile-based elevation service?

I am working on an application that requires the elevation at a given lat/long coordinate for lots of closely spaced coordinates along any given irregular path. (The path is a trace of a ...
6
votes
2answers
112 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 ...
6
votes
3answers
349 views

Precision vs Resolution in elevation data

Update: A good example of my confusion: on the Wikipedia page for "digital terrain model" one can find the following statement about a satellite in the "See Also" section: TanDEM-X: generation of ...
6
votes
1answer
1k views

Python Script for getting elevation difference between two points

I have several stream segments 1000 Km long. I need to find the elevation difference between two consecutive points of distance 1 Km starting from the upstream to downstream. How can I get the ...
6
votes
5answers
338 views

Looking for (nearly) worldwide elevation data

I know the raw ASTER and SRTM datasets. Is there any error corrected version available? Or did anybody already combine the data? At least the ASTER data often misses tiles for costal regions (if there ...
6
votes
3answers
8k views

How to extract elevation from .HGT file?

I want to asign a specific long/lat position on a map the elevation from SRTM3 data files, but have no idea how to find the specific value. So I want some example of how I can find in N50E14.hgt ...
6
votes
3answers
3k views

Raster: How to get elevation at lat/long using python?

I was wondering if anyone has some experience in getting elevation data from a raster without using ArcGIS, but rather get the information as a python list or dict? I get my XY data as a list of ...
6
votes
1answer
13k views

How to calculate an elevation profile for a polyline in arcgis 10 with spatial analyst/3D analyst?

My elevation data is a floating point tif. I have a road for which I need to calculate the elevation profile, but I can´t see the tools to do this. Can I do this with ArcGIS? yours, Rob
6
votes
1answer
166 views

How to get elevation profile from .tif dsm on the web map?

I have my dsm .tiff file, pixels are floating point 32bit values giving the terrain elevation in metres. I need to create a web map where user can draw a path and get elevation profile for that path. ...
6
votes
1answer
60 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?
5
votes
2answers
2k views

Exporting DEM-derived rasters to CSV from QGIS?

I have been able to import into QGIS a set of raster topographic maps and the associated DEM raster maps. It registered the two for me. From there I have calculated the associated slope raster map. ...
5
votes
3answers
2k views

How to transform GPX-tracks into elevation-tracks with any GIS?

I have a GPS track in GPX format available from a recent bike tour and I need and want to do some analysis on the tracks. I'm wondering whether there is any way to transform the GPX data into an ...
5
votes
2answers
518 views

What's the difference between hypsography and topography?

I've recently come across some data that has been labeled "hypsography". I looked it up and it sounds like topography. But this data source has data labeled "topography" separate from its ...
5
votes
1answer
361 views

How to determine the most accurate elevation algorithm

I use an Android GPS cycling app to track my bike rides and I would like to get a reasonably accurate estimate of the total ascent I did on a ride. I understand that GPS is very inaccurate at ...
5
votes
1answer
192 views

Cartographic technique for detailing a 'Focus Area'

I'm working on updating a planning document. Whoever was in charge of cartography last time around used a great technique to identify and showcase focus areas (where to focus money and effort for ...
5
votes
1answer
1k views

Labeling contour lines in ArcMap [duplicate]

Can anybody give me advice on how to label contours as shown in Figure 2 below? I would like to be able to put the label "on" the line, which is easy enough. But I'd also like for the contour line to ...
4
votes
5answers
875 views

Elevation correction ASTER GDEM2 (+10m)

My ASTER GDEM2 has a average elevation error of -10m for my area. (I testet it using 90 defferential GPS reference points and compared it with old Topo25, SRTM, and GoogleMaps). I would like to ...
4
votes
2answers
801 views

how do you identify ridges on an elevation raster?

I was wondering whether anyone might be able to tell me in layman's terms how to extract or differentiate between ridges and hilltops from 10m elevation data using ArcGIS 10.1? Any advice would be ...
4
votes
2answers
1k 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
3answers
757 views

How to get the elevation of the areas in a raster file from SRTM?

I have an SRTM elevation map. How do I get the elevation of each point in the map? I am using GRASS. Is there a GRASS script to do such?
4
votes
1answer
116 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 ...
4
votes
2answers
487 views

Focal statistics to calculate saddle points from DEM

I have a conundrum with Focal Statistics and kernel files. I am been trying to identify saddle points in DEMs. I am attempting to rewrite this (thanks whuber) in a python script for 10.1. I have ...
4
votes
2answers
117 views

How to query DEM elevation values in a web application based on cursor/click point location?

I work for a city government that has LiDAR derived DEM rasters which we would like to make accessible to other departments in the city. The problem is that many departments don't have anyone with ...
4
votes
2answers
286 views

Huge x,y,z dataset into oracle, possible?

I have 200 .xyz files containing 1500000 points each. Is this possible to import this dataset to oracle? It makes a total of 300.000.000 points!!! Background is I want to improve a FME script that ...
4
votes
2answers
593 views

Converting Geocentric to Geodetic

I am only looking for a confirmation of what I believe to be true. If my explaination or conclusion is not accurate I would appreciate it if the reason can be explained to me. Background ...
4
votes
2answers
525 views

How to manually edit 16 bit GDEM elevation data on a Geotiff file

I'm building a virtual 3D terrain scenery using both satellite imagery (google maps satellite) and elevation data from GDEM Aster elevation data (geoTIFF format files). My problem is that the ...
4
votes
1answer
355 views

What functionality exists to calculate Cut and Fill for excavation?

Does qgis have the ability to compare and quantify existing versus proposed elevations?
4
votes
1answer
725 views

Elevation graph from GPX file

I've got many GPX files in the following format: <?xml version="1.0" encoding="utf-8"?> <gpx xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ...
4
votes
0answers
304 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 ...
3
votes
6answers
2k views

shadow simulation from buildings

is it possible to use hillshade function in ArcMap to calculate shadow areas of buildings or simulate shadows of buildings, using DSM of the buildings and the sun angle and azimuth?
3
votes
1answer
141 views

Why not measure elevation from the center of the earth?

In trying to understand Geoid vs Ellipsoid height, I ran across this page. One of the claims is: Zero elevation as defined by Spain is not the same zero elevation defined by Canada ...
3
votes
3answers
341 views

What is Trinity High Water?

This question may be off topic, in which case I apologise. I have a problem where water level is important and I have two water levels defined, Trinity High Water and Mean High Water springs (MHWS). ...
3
votes
1answer
106 views

How to obtain a DTM/DEM from DSM

I need to obtain a grid of bare ground elevation (removing all edifices, trees, roads and man-made elements) for quantitative geomorphological analysis from a high resolution (1 m) DSM obtained by ...