Tagged Questions

Digital Elevation Model (DEM), which could be a Digital Terrain Model (DTM) or a Digital Surface Model (DSM).

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4
votes
2answers
156 views

How to drape a simple jpeg image over dem of some area?

How can we drape a simple jpeg image which doesnot have any geo referencing information over the digital elevation model in order to visualize it in 3D in QGIS?
4
votes
1answer
78 views

How to calculate the volume of several DEMs to obtain elevation and volume changes?

I am trying to calculate the volume of several DEMs in order to obtain elevation and volume changes. I have pixels of 1x1 each one associated to an elevation. I used several methods but non of them ...
3
votes
1answer
77 views

Autocorrelated DEM with QGIS or Grass

I was wondering if there is a way to make an Autocorrelated DEM within QGIS or Grass. I am looking to do this with stereo aerial photography. I am able to do this with a number of COTS tools, but I ...
0
votes
1answer
17 views

ArcScene wont open a high resolution DEM and tells me to select a subset - but how?

I'm using ArcGIS 10.0 and trying to open a digital elevation model in ArcScene. I'm working on a project and got the DEM data from official sources. The resolution of the DEM is 1 meter which is ...
0
votes
1answer
30 views

Global DEM and country borders

I am trying to split up the world into 2 categories based on elevation (below 2000m and above 2000m) while still including a country identifier. So in the end, I would like to have 2 types of units ...
0
votes
1answer
50 views

How to find locations for hydro power using raster analysis?

I have a stream network and DEM file both in raster format. I need to extract values from DEM to stream network. For the analysis in stream network after that, I need to find out the places for hydro ...
0
votes
1answer
98 views

How to calculate surface area of highland region using DEM with ArcGIS (ArcEditor)?

Am shyaka from Rwanda. I use GIS tools and have all required data to perform or calculate surface area from the polygons that have been given by GPS (Trimble) with ArcPad 8. I originate from a high ...
6
votes
0answers
87 views

Automatic detection of breaklines with a DEM

Breaklines are very useful for describing a terrain - for example to build an exact TIN. My question is, how to extract these breaklines from a given DEM. I calculated the curvature (vertical) - ...
3
votes
0answers
62 views

Shapefile and DEM: check rivers behaviour

I'm working with shapefiles representing rivers (rivers.shp), and DEM for the terrain elevation (terrain.tif). Basically, I want to check that my rivers (stored as polylines in my shapefile) behave ...
3
votes
0answers
30 views

Adjacent DEM files have narrow triangular gaps when joined

Newbie here. I've downloaded several DEM files from GeoCommunity which correspond to adjacent regions. When I join them together to form a larger relief map there are triangular 'gaps' on all four ...
2
votes
0answers
49 views

Arcpy: Counting number of segments where altitude rises or decreases based on DEM?

I have a DEM of Sudety mountains and linear .shp with several hiking paths. I'm trying solve one problem: How to make a script based on input DEM and input line shapes that would count number of ...
2
votes
0answers
136 views

tools from Geospatial Modelling Environment in ArcMap model

How to extract raster DEM elevations to vector attribute tables in ArcGIS 10? Can GME tools be used in model for publishing a tool on web? I want to use it in integration with other tools in ArcMap. ...
2
votes
0answers
314 views

How to calculate Solar Radiation falling on vertical surfaces using DEMs and ArcGIS?

I am using ArcGIS10 Area Solar Radiation tool to calculate irradiation on horizontal surfaces (building roofs) but need to do the same for vertical surfaces (building facades). Any ideas on how to do ...
2
votes
0answers
313 views

GDAL tiling DTED (dt2) dataset as gdal2tiles for 3D Maps

i am searching some webgl technologies to create 3d map with digital elevation data. for web tech. i have found ReadyMap SDK to create 3d map from TMS... in ReadyMap for elevation data it uses sth ...
1
vote
0answers
65 views

“topo to raster” tool

is there any analogue of "topo to raster" tool (ArcGIS) in QGIS? I need to creates surfaces from shp for some cases from points and for some from lines and this instrument is very convenient.
1
vote
0answers
238 views

How to create a profile with profile points at discrete altitude intervalls, e.g. each 10 m

In both SAGA and QGIS theres a profile-from-line-function that does a nice job of creating profiles. But there's no way to control the altitude spacing. Any ideas for workflows that would allow me ...
0
votes
0answers
2 views

A library/software to create DEM from a topographic map

In one of my projects I need to digitize video clips showing some natural landscape. Specifically I need to know distances between different areas and elevation levels. I have a topographic map of ...
0
votes
0answers
34 views

How can i calculate the width of the dam?

I am working with Reservoir design. Now I am facing problem to calculate the width of the dam. I need to calculate the width based on DEM and height of dam at various points using Python. I am working ...
0
votes
0answers
25 views

catchment delineation

I am trying to use qgis to delineate between three sub-sub-catchments. I have contour shape file of 20 meter height. Sub-catchment is about 12 square kilometers area but consist of three ...
0
votes
0answers
11 views

Input data format and read multiple files into Grass 6.4.1

I am trying to read in multiple (hundreds, thousand) LiDAR ascii files into Grass. They contain elevation data. I think I have managed one, and I can make a map of elevations, using File, Import ...
0
votes
0answers
26 views

gdal_merge.py aligns incorrectly at the seam of two GeoTiffs

I am trying to merge four GeoTiffs from the National Elevation Dataset (EPSG: 4269) into a 2x2 DEM using gdal_merge.py. For some reason, when it merges the upper two NED rasters, gdal produces a seam ...
0
votes
0answers
11 views

How to represent scale in legend after using '1-Band Raster Colour Table V1.x' for DEM

I was able to represent the DEM by one of the nice colour ramps with the 1-Band Raster Colour Table V1.x plug-in. How can I correctly represent this colour ramp in the legend, as it contains 255 ...
0
votes
0answers
74 views

Digital elevation Model trouble

I've got a DEM with a resolution of 15m covering a small part of the UK. I am trying to use it calculate slope angle in ArcGIS 10.0. However when running the slope tool the problem I'm having is the Z ...
0
votes
0answers
108 views

Importing Large Raster Datasets in Global Mapper

I'm having issues importing large amounts of data. I have about 25 gigabytes (2752 files ) that im trying to export as one big hill shade. I did this successfully in ArcGIS but i wasn't happy with the ...
0
votes
0answers
152 views

slope and mosaic datasets

I was wondering if anyone has had any experience with combining multiple DEM’s into a mosaic dataset. I am working with several DEM’s and need to convert them to slope. I’m having an issue with ...