The vertical and horizontal dimension of land surface

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3
votes
1answer
362 views

Hydro-Enforced/surface constraint DEM Creation using GRASS/QGIS

I am wondering if there is a way to create a hydro-breakline enforced DEM by means of any open source solution? I am able to create a DEM from Lidar data using GRASS, but would like to enforce some ...
1
vote
1answer
210 views

calculating terrain elevation line

I found too many hits on the web to even see the right direction to go. I have to provide a small proxy server serving requests for a line of terrain elevation data between two coordinates. It is a ...
2
votes
1answer
4k views

Can Compound Topographic Index (CTI) / Topographic Wetness Index (TWI) produce negative values?

I am calculating Topographic Wetness Index for a study area using SRTM DEM (90 and 30m). I've seen several versions of TWI (CTI). I have been using: TWI = ln(As +1 / tanB) where As = ...
6
votes
3answers
1k views

Where I can find world terrain data?

I need free terrain data for the whole world which I can import into TileMill. Is there some source where I can download them? Thank you.
1
vote
1answer
71 views

How to conflate terrain data?

I have an 8 km by 8 km raster of 20 m/pixel terrain data. The georeference data has been lost. All I know is that it's within 100 km of Smithers, BC. I realize that this might involve some very heavy ...
1
vote
0answers
32 views

Styling a raster on relief shading analysis [duplicate]

Possible Duplicate: How to create a style file for QGIS from a plain text file? I have a text file which contains the following data eleva R G B 0 153 255 153 100 179 255 ...
21
votes
4answers
3k views

How to calculate terrain Curvature?

I have an elevation raster and I would like to get some basic terrain variables, such as slope, ruggedness, aspect or curvature. The problem is that I don't seem to have the possibility to calculate ...
6
votes
2answers
567 views

Problem Visualizing 3D Terrain Model - USGS DEM

I recently downloaded a GeoTIFF 1 arc second from the USGS National Map Viewer. I added the raster to ArcScene and attempted to visualize the data in 3D. I set the Base Height to Floating on a ...
9
votes
2answers
1k views

Floodplain generation given river section polylines, flood level elevation points and a DEM of the land surface

I am looking to generate flood plain polygons to represent 20 and 100 year flood zones, in the most accurate and efficient way possible, given the following datasets: 1) River cross section polylines ...
5
votes
1answer
204 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 ...
1
vote
3answers
199 views

Terrain Beautification

The satellite imagery i am rendering is not realistic does not look good. So i was planning to improve things through code(like adding noise to data or using different overlay texture for different ...
6
votes
1answer
8k views

Which is better, DEM or Triangles (TIN/Terrain)

Which is better DEM or TIN? What are the benefits/negatives of each?
1
vote
1answer
510 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 ...
20
votes
8answers
1k views

How to generate a random but believable digital elevation model?

Is there a way to generate a DEM, programatically or otherwise (arcpy or R?), that will feed into ArcGIS for further spatial analysis? Perhaps this needs to be broken down into smaller incremental ...
8
votes
2answers
969 views

TRI, TPI, or Roughness

I am working on a site selection projection where I will be unable to perform any in situ observations. A key component of the selection process is the ruggedness of the underlying terrain. I plan ...
3
votes
4answers
5k views

Can I convert ESRI Grid (DEM) raster to USGS DEM?

There is a tool for DEM to Raster in ArcGIS but I need to convert my ArcGIS DEM rasters (mostly LiDAR) into USGS DEM. The idea is to import this DEM into Sketchup and create a "sandbox" TIN surface ...
16
votes
5answers
3k views

Given a terrain, how to draw the stream flow path?

Assuming I have a terrain, as usual the terrain has ridges, creeks and all the characteristics that you can find on a real life map. Water flows from the top of the mountain into lower area, the path ...
6
votes
3answers
1k views

How to find the elevation differences between adjacent pixels in ArcGIS?

Is there a way to determine what the difference in elevation is between two adjacent pixels? I am using an SRTM DEM to map faults. I am using the vertical error (>16m) as a criterion for the ...
18
votes
7answers
6k views

Are there open access terrain tiles with a permissive license like OSM?

Are there open access terrain pyramidal map tiles with a permissive usage license like OpenStreetMap's? I'm building aviation-related maps with Polymaps and need a good raster basemap. The Google ...
6
votes
2answers
337 views

Auto Balancing in EarthWork

I am not sure whether this question belongs here. I think it belongs more to Geo-technical, but anyway, I just give it a shot. During earthwork development, earth terrain has to be cut ( if the ...
2
votes
2answers
328 views

Where I can find real world data for triangulation?

I want points for practicing triangulation algorithms. Just points with coordinates [X,Y] and elevation [Z] of real world terrain. I can use Google Maps Elevation API, but there is no method how to ...
0
votes
0answers
646 views

buildings shadow areas calculation

is it possible to calculate shadow areas of buildings or simulate shadows of buildings in a city using e-cognition software, with the DSM of the buildings and the sun angle and azimuth known?....if ...
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?
8
votes
5answers
23k views

How can I create profile cross-sections in ArcGIS 10?

Because the default 'Profile Graph' tool was not sufficient, I wrote a custom VBA script that creates scaled and exaggerated profile cross-sections in ArcGIS but I need more features: Visualize more ...
2
votes
1answer
143 views

What is a “CFG” application in GIS terminology probably?

I come across a 2008 tech presentation PDF on "GIS-Enabled Modeling and Simulation (GEMS) presented by ESRI (i think for the US Army). On one of the page titled "Challenges to be overcomed", there is ...
7
votes
4answers
525 views

Which ArcGIS product gives full 3D terrain navigation and (flight) simulation?

I looked at the ArcGIS ESRI website and find that 100% of the screenshots depicts a 2D map with at most relief shading. Is there any product ArcGIS or not that gives real 3D terrain visualisation ...
8
votes
6answers
1k 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 ...