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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" ...
Dan C's user avatar
  • 12.3k
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 ...
Richard's user avatar
  • 1,831
8 votes

Creating topographic "layer cake" map a.k.a. Tanaka contour in QGIS

Illuminated Contours, often called Tanaka Contours. There are many different ways of creating them in QGIS. Keep in mind that quite a few of the older tutorials are now out of date as newer versions ...
Tom Brennan's user avatar
  • 5,249
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 ...
ahmadhanb's user avatar
  • 41.1k
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 ...
Billy34's user avatar
  • 691
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 ...
Mikkel Lydholm Rasmussen's user avatar
5 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://...
ramin orkide's user avatar
5 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 ...
Jeffrey Evans's user avatar
4 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. ...
Karsten D.'s user avatar
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 ...
pavlos's user avatar
  • 3,538
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 ...
mgri's user avatar
  • 16.3k
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,...
csk's user avatar
  • 24.9k
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. ...
Joseph Lewis's user avatar
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
atxgis's user avatar
  • 1,239
4 votes
Accepted

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 ...
Roberto Ribeiro's user avatar
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 ...
Spacedman's user avatar
  • 65k
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....
AndyB's user avatar
  • 812
4 votes
Accepted

Cutting/ exporting multiple terrain profiles to CSV files with QGIS?

Use the Sample raster values or Add Raster Values to Points tool to extract raster values: Make sure each line has a unique attribute, eg "Line_ID". Convert the lines into points Use the Extract ...
csk's user avatar
  • 24.9k
4 votes

Profile tool and GPS data in QGIS

Steps with the Profile Tool : Open both the track and track_points in QGIS. Open the Profile Tool plugin. Select the point layer in the Layers Panel and click on Add Layer in the Profile Tool. Choose ...
Léo M's user avatar
  • 620
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 ...
GBG's user avatar
  • 10k
4 votes

Creating topographic "layer cake" map a.k.a. Tanaka contour in QGIS

You are correct -- it's called Tanaka Contours. I also found this helpful video: https://www.youtube.com/watch?v=ORvdWyGCUVQ I will mark this as solved/answered once my permissions let me in 2 days. ...
Jon Altschuld's user avatar
3 votes

DTM extraction of tree heights

one possible approach (assumes you have DSM as raster, and no DTM). I've tried this on a local park (Princes Street Gardens in Edinburgh). It's probably a bad example as it's not on a continuous ...
Steven Kay's user avatar
  • 20.5k
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 ...
Jeffrey Evans's user avatar
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 ...
emackey's user avatar
  • 1,456
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. ...
Matte's user avatar
  • 6,255
3 votes

QGIS Profile Tool shows no profile

Here you have the screenshot with the sequence to get the profile of a line: Click on your dem file. Click on "Add layer" button. Click on the points between you want to see the profile (double ...
César Arquero Cabral's user avatar
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 ...
Kazuhito's user avatar
  • 31k
3 votes

How should I interpret R terrain/slope output in degrees?

If I construct a raster with rows of height from 1 to 10, in a square 10x10 grid of cells of size 1m, I've created a 45 degree slope: > r = raster(matrix(1:10,10,10), xmn=0, xmx=10, ymn=0, ymx=10) ...
Spacedman's user avatar
  • 65k
3 votes
Accepted

How do I calculate the Terrain Ruggedness Index for each county in the United States in R?

Just because something is published does not mean that it is necessarly correct. In this case aggregating the TRI to a county is certainly incorrect. The distributional qualities of the metric, in ...
Jeffrey Evans's user avatar
3 votes
Accepted

My 3D polygons are being drawn below terrain

Found the solution here and here. var promise = Cesium.GeoJsonDataSource.load('/resources/buildings.json'); promise.then(function(dataSource) { viewer.dataSources.add( dataSource ); viewer....
Magno C's user avatar
  • 2,150

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