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13 votes

Slope, in which direction?

The direction of a Slope is known as its Aspect. It's usually defined as the direction the slope "faces", to me that's a little ambiguous and it's more intuitive to think of it as the "downhill" ...
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  • 12k
11 votes

In hydrologic terrain analysis is there a difference between "pits", "depressions", and "sinks"?

There is a difference, and I recommend the typology presented by Lindsay (2015) be used. Lindsay (2015) presents a typology which defines a pit as a single cell in a DEM whose elevation is below that ...
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  • 1,761
6 votes
Accepted

ArcPy delete terrain: cannot be deleted

I was able to replicate your problem, but found a solution. You have to remove the datasets that are used by Terrain dataset first before you can delete it. A bit weird but that seems the way it must ...
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  • 38.3k
6 votes

"Relief" function from the Raster Terrain Analysis plugin in QGIS 3.0

If you search for Terrain analysis in the Processing toolbox you will find what you want. The tool moved from Raster -> Terrain analysis to Processing Toolbox -> Raster Terrain analysis: I am ...
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  • 36.1k
5 votes
Accepted

OpenLayers & Google Maps: TERRAIN not showing as baseMap

You could just use a different version of google-maps-api, for example http://maps.google.com/maps/api/js?v=3.5&sensor=false Example: http://jsfiddle.net/expedio/sodserrw/ The same example with ...
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  • 6,320
5 votes

Algorithm for smoothing DEM without losing max and min elevations

What you want is an adaptive filter - something like the Edge-Enhanced Modified Lee Filter (see this article). The basic idea is that the amount of filtering depends on the local variance - the more ...
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5 votes

Algorithm for smoothing DEM without losing max and min elevations

To complement @Mikkel's answer, you coul'd find that tool in SAGA GIS (open source). The tool is "Multi Direction Lee Filter" and quoting from documentation The tool searches for the minimum ...
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  • 651
4 votes

Calculating terrain Curvature in QGIS

LandSerf can do this .You can define windows size (3*3, 5*5, 7*7, 11*11,...) but it must be odd number. multiscale analyses. you can consider scale dependency of slope, Aspect and curvature. http://...
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4 votes
Accepted

How can I extract flat surfaces from a DEM with GRASS GIS?

Run the aspect tool r.slope.aspect. Try the < min_slope option set to a very low number. The unclassified areas are your flat area. Play with the setting to get it just how you like. You can ...
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4 votes
Accepted

Remove terrainProvider from scene (ol3-cesium)

use the following function to toggle the terain function toggleTerrain(){ var scene = ol3d.getCesiumScene(); var terrainProvider; if (scene.terrainProvider._url){ //add a ...
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  • 3,488
4 votes

How SAGA calculates Convergence Index

In the SAGA-GIS Tool Library Documentation (v2.1.3) there is a reference to the method which is used for this calculation: Koethe, R. & Lehmeier, F. (1996): SARA - System zur Automatischen ...
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  • 15.5k
4 votes

How to style rocky coast?

You can achieve something similar with a marker line with variable-size rectangular markers. Tweak the values in the data-defined marker size expression to get the right variation in size. rand(1,...
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  • 23k
4 votes

QGIS: Terrain accessibilty in hours/days usind DEM/CSV data

From the grass comands section you can use use either r.cost or r.walk to define your cost surface. Then you can use r.drain to calculate the least cost path, so I'm not sure why it's not working. ...
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4 votes

Finding Rocky Outcrops

I would think about using a supervised classification, which will identify all the rocky outcroppings by their image signature. Supervised image classification in QGIS
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  • 1,239
4 votes
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Using slope and total height for terrain analysis in QGIS?

This can be done in a few ways, but using QGIS specifically, the best way I can think of is using Map Algebra. The idea is to first get all areas with a slope above your desired threshold, then ...
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4 votes
Accepted

Nested loop and terrain analysis R

This: terrain_bound <- lapply(nlayers(dhm_terrain), function(i) { should be: terrain_bound <- lapply(1:nlayers(dhm_terrain), function(i) { (or use pblapply - I took it out in order to see ...
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  • 51k
4 votes
Accepted

Using terrain correction in SNAP sentinel 1 toolbox removes all the values

This is a known issue and caused by inaccurate access to the SRTM 3Sec (Auto Download) data which is required for the terrain correction. Usually, it is automatically downloaded but the access changed....
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  • 665
4 votes
Accepted

Reproducing terrain ruggedness index from the original paper example

I hate the be the bearer of bad news but, Riley et al., (1999) is wrong. The ruggedness index itself is fine but, the example in the paper is incorrect. Obviously, the reviewers did not work through ...
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4 votes

Converting aspect/direction raster from geographic degrees to arithmetic radians

The aspect tool in QGIS has an option to output your aspects in trigonometric angle. This would give you 0 as due east, 180 as west, 90 as south, and 270 as north. Then just multiply the result by ...
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  • 7,107
3 votes
Accepted

Software for amateur topographic surveys

Copan Lite should do exactly what you need. It's a free, GUI-based Windows COGO tool for land or topographic surveyors. (I was heavily involved in its development.) From the Field Bearings Processing ...
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  • 8,584
3 votes

Software for amateur topographic surveys

You can try GNU Gama. According to its project page: GNU Gama is a project dedicated to adjustment of geodetic networks. Adjustment of geodetic networks means that we have a set of points ...
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  • 17.2k
3 votes
Accepted

Which Statistical Test to use?

It is really quite straightforward to obtain a Pearson's correlation coefficient. Given a population assumption: xBar = mean(x) yBar = mean(y) xyBar = mean( (x * y) ) covariance = xyBar - xBar * ...
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3 votes
Accepted

How do I use the Terrain with Labels basemap in the Map constructor

You can combine the two layers as a single Basemap and pass them to the map constructor. Below is a full working example using the two layers you are interested in. This came from a discussion we had ...
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  • 1,494
3 votes

Generating random but believable digital elevation model?

This code can be used to create a "Hill slope" DEM of just about any number of rows and columns: # Building a fake hillslope # hisllop is 5 rows by 6 columns x <- seq(-15, 15, by=0.01) z <- 1/(...
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  • 2,010
3 votes

Free Digital Elevation (Terrain) Model of Europe or Germany

For Germany you can order the DGM10 from the Federal Agency for Cartogrpahy. The Official Elevation Datasets are available in 10 m to 1000 m spatial resolution with a height accuracy of 0.5-2 m.
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  • 9,400
3 votes
Accepted

Open source tools to create quantized-mesh tiles for Cesium?

My currently preferred solution is Cesium Terrain Builder Docker. It is an extended version of the Cesium Terrain Builder with support for quantized-mesh-1.0 and can be easily run using Docker. ...
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3 votes
Accepted

Drone that generates a point cloud from photography

Probably they have made a structure from motion function. With the mosaic of several pictures around an object you can create its 3d model and get also the point cloud. Thats nothing too spectacular. ...
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  • 6,015
3 votes

DEM classified using SAGA GIS and conversion to point shape

You can probably use either Add Grid Values to Points or Grid Values to Points tool. They are under "Shapes- Grid" of Tools manager. (see below image, from SAGA 2.1.2) If you already have a Point ...
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  • 29k
3 votes

Cesiumjs 1.32 and ArcGIS 10.2 - ArcGisImageServerTerrainProvider is being deprecated - how to provide terrain data

Here's the issue where it was decided to deprecate ArcGisImageServerTerrainProvider. The reasons given (by one of Cesium's core terrain/imagery developers) are quoted here: We probably should have ...
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  • 1,434
3 votes
Accepted

Slope, in which direction?

With the back-and-forth comments, I am honestly not entirely clear as to what you are after here. In a quantitative sense there are metrics that provide an interaction of slope and aspect, that forest ...
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