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

learn more… | top users | synonyms

3
votes
3answers
758 views

How to change layer transparency without changing border lines?

I have a raster image of elevations. I have added a vector shapefile that contains local political divisions. I want to keep the elevation colors, but I want to keep the black lines representing the ...
2
votes
1answer
44 views

How do I find out the sea levels?

I have following elevation data of a region (the higher the altitude, the brigher the points): How can I find out, which areas are filled by water, and which not? Can I assume that if the ...
1
vote
1answer
502 views

Using GDAL to read dted files

How do I get the elevation at a certain point using gdal to read in a dted file? I don't see much useful information out on the web. I'm sorry I should have been more specific. How would I ...
1
vote
2answers
86 views

Suitable raster format for elevation data with sub-meter accuracy?

I've got some elevation data represented in ascii gridded xyz-files which I want to convert to a conventional raster format. What's a bit special is that the elevation values have sub-meter accuracy, ...
1
vote
1answer
26 views

QGIS - Level curves - Voronoi Polygons

I am facing a difficulty in QGIS (2.8.2): I have three layers: layer 1: layer with points layer 2: layer of level curves (contour lines) layer 3: layer of Voronoi polygons obtained from the points ...
0
votes
1answer
42 views

GRASS 7 Cost surface and elevation points development

I'm a new to GIS and I need some help. At the moment, I'm trying to develop an optimal path across an area by using GRASS 7 features. It is very similar to the task given here. The problem is that I ...
1
vote
1answer
840 views

How do I add elevation data to a GeoJSON line from a GPX file?

I understand that elevation can be added as an optional third value in Coordinates (lat, long, elev) in a geojson file, but I can't find a way to actually do that from a gpx file. I've used ogr2ogr to ...
5
votes
1answer
151 views

How to find all points with certain elevation difference between them in QGIS

I have a point layer (xyz) and want to find all points that have elevation difference of 200m or more. I would like to then draw a line between each pair with the largest elevation difference. The ...
10
votes
3answers
500 views

What is the meaning of “Elevation above the surface of the ellipsoid”?

I'm using implementation of Vincenty's algorithms, and I have their class called "position" that requires lat, lon, and elevation defined by: "Elevation above the surface of the ellipsoid". What is ...
3
votes
1answer
186 views

How to map flood areas from a set of points containing surface and height of water?

I am working on the damages made by the typhoon Haiyan. I use QGIS 2.0 with extensions and toolbox, and MapInfo. I have vectors, rasters of the place. I want to map the flood area along the ...
0
votes
1answer
19 views

Regarding ARCGIS Curvature values [closed]

I originally had a DEM .tif raster in Decimal degrees. I projected it into a PCS with the spatial reference in ArcGIS as: WGS_1984_UTM_ZONE_44N Then, I took the Curvature tool and with a Z-factor of ...
1
vote
2answers
37 views

Topographical Elevations for Central Africa and Cameroon

I am using QGIS and I have been faced with the problem of topographical maps. From searching online I could only find data for the United States. Google maps offers elevation contours, however I am ...
4
votes
2answers
691 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 ...
0
votes
1answer
29 views

How can I determine elevation levels for a region in Java?

I need to find out the elevation levels for a certain region (center is located at 132.159633, 43.350116). For this purpose I went to the Elevation finder and downloaded there the relevant part of ...
0
votes
0answers
30 views

Which elevation data source has the highest precision for Russian Far East?

If I want to get data on the elevation around the city of Artyrom (region around 132.159633, 43.350116), which elevation data source has the data with the highest precision for that region? I found ...
0
votes
0answers
37 views

Calculating ground cover along a path

I'm trying to figure out an efficient way of pulling data about ground cover along a specific path, where I know the starting lat/long and the end lat/long. I've found that the USGS has ground cover ...
0
votes
1answer
37 views

Determining length of roads that fall under low elevation using ArcGIS Desktop?

I am working on a project on sea level rise impacts of roads. Basically I need to determine length of roads that fall under low elevation (from 1m to 5 m elevation). I have a DEM file and road shape ...
0
votes
0answers
54 views

Raster map source for desktop, commercial application

We develop desktop, commercial application for Architects (c++). In a future update, we would like to provide our customers with the option to automatically create a 3D terrain with appropriate ...
1
vote
1answer
100 views

Ranking Elevation using QGIS?

Can QGIS automatically find the lowest land-point in a country and when you would like to, find the second lowest, third lowest land-point and so on? And on that same coin, a software that could find ...
1
vote
0answers
46 views

calculate Z~F from polygon and raster

I have a polygon shapefile and raster layer. How I can calculate the elevation and area (Z~F) relationship for each polygon by using QGIS or ArcMap?
2
votes
1answer
203 views

Computing the elevation angle of a GPS satellite with respect to the given receiver location

can anyone source an explicit formula for calculating the elevation angle for a GPS satellite as seen from a receiver. I can't seem to find one. Even a text reference would be great. I couldn't quite ...
1
vote
1answer
46 views

Generate 3D elevation points grid from 3D contour lines!

I have a shape file with 3D contour lines. I want that based on this information to generate for all this area a 3D grid of points with certain distance from each-other like every 50cm. I use ...
2
votes
0answers
31 views

From track+waypoints to elevation profile with waypoints

I have a track and waypoints (1) imported in QGIS. I want to calculate the closest point from every waypoint to the track (2). Then, I want a table with data that allows me to draw an elevation ...
1
vote
1answer
43 views

How can I create polygons for a 3D map from a DEM in grass/qgis

I have a SRTM 30m DEM of my area. I want to create a physical 3D terrain map from it (from felt, 3D printer, you name it). I have two questions about this process: With grass r.contour I created ...
2
votes
1answer
87 views

How to perform viewshed analysis with Dutch AHN files?

i downloaded the new (dutch hight data) AHN files, and was trying to perform a viewshed analysis at some point near UTRECHT. The plugin (grass plugin) works ok, i tried it before with a dem map. ...
1
vote
1answer
51 views

Is it better to take the elevation of a GPS unit or that of a Digital Elevation Model?

When searching of gps routes in wikiloc, for the trailrunning race "Transvulcania" I have several routes to look. I downloaded a lot, but every route has a distance between 71 kilometers and 74 ...
0
votes
1answer
41 views

Generating elevation 'database' from NED IMG data

I'm starting to work with the NED 1/3 and 1/9 arc-second data. I've been using gdal in Python and QGIS to do some basic conversions of the raw .IMG data from USGS. My goal is to get elevation data of ...
0
votes
1answer
27 views

How to input Shapefile point data into a raster and have the raster adjust to the new data?

I have a shapefile with elevation data at specific points. I also have a raster that has incorrect elevation values, but the transition between pixals is what I need. Is there a way to put the values ...
-1
votes
1answer
25 views

ArcGIS elevation? [duplicate]

I would like to get the elevation of different point in the digital elevation model means around 4000 points would any one please tell me how can it be possible.
9
votes
2answers
1k 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 ...
0
votes
0answers
38 views

Using Raster Calculator with Elevation Data from Contour Map

I am following this tutorial to attempt to determine flooding in the Gulf region based on estimated rises in sea level. I have taken topographic maps from the USGS and used to contouring tool to turn ...
17
votes
3answers
6k 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 ...
0
votes
2answers
111 views

Seeking web service that returns elevation profile between two points and can process 5000 requests per second

I need a web service that provides elevation profile data between two coordinates with request rates at a minimum of 2000 requests per second but preferably at 5000 per second. The distance between ...
4
votes
6answers
3k views

shadow simulation from buildings [duplicate]

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
2answers
104 views

Kriging values greater than the most extreme value of the input layer?

I'll admit I don't understand kriging to the fullest. Yet, I've read that the weights should add up to 1 as in IDW and Natural Neighbors. However, surrounding the biggest elevation points of my ...
1
vote
0answers
18 views

QGIS Extract elevation data only for one country [duplicate]

I have a map built with a shapefile for country contours and a raster from .hgt files with elevation representation. How can I only select the area corresponding to the country? I found some thing ...
2
votes
1answer
361 views

Extract elevation data from Landsat / MODIS imagery?

Just curious, have anyone tried to extract elevation data from LANDSAT or MODIS imagery? So far, I came across one journal by Toutin who did so using adjacent LANDSAT 7 imageries. Results seem pretty ...
5
votes
3answers
1k 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 ...
7
votes
3answers
559 views

Precision vs Resolution in elevation data

Update: A good example of something I am confused about: on the Wikipedia page for "digital terrain model" one can find the following statement about a satellite in the "See Also" section: ...
1
vote
0answers
51 views

How to get the elevation of the complete sea floor?

I am not a cartographer, I am an analyst-programmer, I know nothing about SRTM, DXF, PostGIS, QGIS... I just saw those names in other questions... Is there a quick guide where I can learn about this? ...
5
votes
2answers
2k views

How to create contour lines from point data using QGIS?

I'm using QGIS 2.4.0 and I have a shapefile of points with elevation data and X and Y coordinates. I'm using windows 7 OS. The idea is to create a contour line SHP using my point data. My question ...
1
vote
0answers
56 views

Modifying DEM elevation data in QGIS using a polygon

I've tried searching through the existing questions but am struggling to find a succinct answer to what I am trying to achieve. For background, I am running a flood model in TUFLOW to help support a ...
4
votes
5answers
1k 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 ...
0
votes
0answers
35 views

Extract value from Raster data by elevation

I have one raster data (AVHRR NDVI value) and one dtm data (elevation value). Is there anyway to know the NDVI value by 50m interval elevation? For example, I wanna know what is the NDVI value for ...
1
vote
0answers
45 views

Trajectory / ballistics

I'm trying to calculate if a canon will be able to shoot over a height in the terrain. lets saytThe canon have to be 15'000-18'000m from the target, and the impact degrees have to be over 30 ...
1
vote
0answers
34 views

Where can I obtain data on flood sites, land sewage systems, and property value?

I am a college student trying to obtain this data for a class project. If anyone can help that would be great. Basically, my hypothesis for this project is that land sewage systems that have not been ...
2
votes
2answers
60 views

find elevation for series of (lat,lon) combinations to make 3d model of earth with relief

I would like to say I am a complete novice to the world of GIS, so if I ask stupid questions or make strange assumptions, please point it out and I will try to clarify myself. I would like to make a ...
11
votes
5answers
8k views

How to calculate Topographic Ruggedness Index in ArcGIS Desktop?

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 ...
0
votes
1answer
65 views

How do I take a contour .shp file and create a separate layer for each elevation?

The end result is to have a .dxf file in which each different elevation resides in a different layer. If at all possible I would like to be able to do the organizing in tile mill, or through some ...
1
vote
0answers
32 views

cutting contour lines over raster (building) areas

I am looking to cut the contours in ArcMap and /or AutoCAD so they don't pass through buildings or roads. Is there a process or code to do this, so it doesn't have to be done manually? Also, looking ...