Questions tagged [contour]

Contour maps depict spatially-varying values, such as elevation, by means of curves of equal value.

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252 views

Orientating Contour Labels Uphill in QGIS?

I'm quite new to QGIS and I'm trying to style topographic contours. I have managed to style the lines the way I'd like but I'm having trouble with the line labels - I can't style them so the labels ...
4
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419 views

Adding intermediate contour values automatically in QGIS?

We have 100's of elevation contour shapefiles. In each file, only the 10th contour line has values (200, 450, 700, etc..). We have to attribute values for all the intermediate contour lines (2nd line ...
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165 views

Removing noise selectively from DEM using QGIS?

I am looking for a processing tool that can remove noise selectively from a DEM (Mostly SRTM). My current workflow includes "Fill sinks" and "r.neighbours". The problem is that the tool is blind to ...
3
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285 views

Why does Contours plugin crash QGIS 2.18?

I am running QGIS 2.18 on a mac and trying to use the Contours plugin. I've never had problems with it before but then I updated QGIS using Kyngchaos. Now Contours crashes QGIS when I choice "Filled ...
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212 views

Which STRM resolution Srtm2Osm.exe uses?

The piece of program Srtm2Osm uses SRTM elevation model from NASA to produce countour lines in OSM format. Does it use the SRTM1 at 30m or SRTM3 at 90m?
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155 views

Open source alternative to the “Contours with Barriers” Tool in ArcGIS

I am trying to create a contour file for the globe for a project and am using open source GIS software packages. I was trained for several years on ArcGIS and there is a tool to create contours with ...
3
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0answers
430 views

Creating a DTM from Contours, via the command line or Python

I am looking to create a gridded DTM/DEM (Digital Terrain/Elevation Model) or TIN (Triangulated Irregular Network) from a set of contours. There are a number of similar questions on both this site ...
3
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0answers
1k views

Formula for maximum coverage of a geostationary satellite based on earth station elevation

I am trying to create a JavaScript function to represent the maximum coverage of a geo satellite for different antenna elevations (0 degrees, 5 and 10 degrees) with 3 leaflet polylines. The result is ...
3
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0answers
2k views

Arrow flow lines from a contour map

using QGIS (or even GRASS) is it possible to label a contour lines shape with arrows that indicate the flow direction? Briefly: I have a point shape with elevation values. I make an interpolation map ...
2
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0answers
44 views

Use edge detection to segment images

I have an RGB from which I detected the edges and I'm curious if I can use it to optimize a segmentation or as a mask to improve the segmentation to identify cultivated fields. Could you do that? If ...
2
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0answers
66 views

Smooth contour lines/correctly extract contour lines from a DEM in QGIS

I have a DEM obtained as a result of the interpolation of elevation points TIN Interpolatin: I extracted the contour lines in QGIS and the result is this: After I tried to apply the Line Smoothing ...
2
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0answers
22 views

Using QGIS Webmap with Mapbox

Im trying to produce a contour map using QGIS and exporting using Mapbox. The map is rotated 90 degrees in QGIS and it returns to its normal orientation if I use Leaflet. Unfortunately, using the ...
2
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0answers
41 views

Contour Polygons to 3D

I am trying to make a 3D representation of the map below. I have 3 polygons which represent contour lines. It starts at 0ft for the outside polygon, 10ft in the middle and 20ft for the very center ...
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0answers
248 views

I get “The following layers were not correctly generated.” error (Raster -> Extraction -> Contour) QGIS

No matter what parameters I enter for the contouring, I always get the response in the log of "The following layers were not correctly generated." I'm working QGIS 3.6. I am not familiar with this ...
2
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0answers
223 views

Exporting contour labels to DXF

I am very new in QGIS. I imported a DEM in QGIS, I generated contours, then I have added some labels. I have been able to export those contours in DXF but the labels haven't been exported. How can ...
2
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0answers
322 views

QGIS Contour Extraction Malformed Path (QGIS 3.0.1 Girona)

I'm attempting to create contours from a raster DEM (provided by USGS). I open the dialog at Raster > Extraction > Contour, choose the input level, leave the default Band number of Band 1, set an ...
2
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0answers
247 views

Creating 3D geographical maps for physical fields in qgis

We need to reproduce 3D maps of a certain physical property on a geographical area changing with depth (in the case of the example these are surfaces of equal subsurface temperature). The example ...
2
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0answers
67 views

Contour Plugin generated contours do not have enough nodes

I am using the contour plugin to generate intermediate contours. I have a vector file with 5 foot contours and want to interpolate 1 foot contours from it. The procedure I used was: Extract nodes ...
2
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0answers
72 views

Using QGIS to contour in Fedora 26?

I have a problem with QGIS. When using the contour tool I get the following error: The process failed to start. Either the invoked program is missing, or you may have insufficient permissions to ...
2
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0answers
42 views

Why are there null geometry lines after using the contour tool in Spatial Analyst?

A few months ago, I ran the Contour tool on two separate DEMs (one was smoothed and the other wasn't). The contour interval was set to 1m. Today, I noticed that there were several features created ...
2
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0answers
318 views

Optimize Postgis contour lines DB

I'd like to try to optimize a world-wide 10m contour lines (isohypses) Postgis database(from SRTM). The complete DB takes 504GB on disk, contour lines are already in epsg:3857, and simplified with ...
2
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0answers
167 views

Adding z values to contours without attribute data

I have a set of contour lines with 5 meter interval which doesn't have any height set in the attribute data. Now I'd like to assign (preferably automatic) z values to these contours since I want to ...
2
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0answers
205 views

How do I calculate kernel density using cases and controls in QGIS?

I have a dataset with approx 1250 geolocated points - approx 150 are cases of a disease and the rest are controls. My area of interest is around 20km by 20km with wide variation in population density. ...
2
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0answers
113 views

Fixing undesirable lines between tiles from SRTM contour line extraction?

I'm trying to make a South American topography map based on SRTM data on QGIS. The problem is a visual one. If the topography contours are extracted from individual SRTM tiles, it results a little ...
2
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0answers
577 views

Generate contour lines for big DEMs and import into PostGis

I've downloaded the SRTM DEM files for most of Europe, from both 3arc_v4.1 and 1arc_v3 versions. The first comes in 5x5 degrees tiles, the latter in 1x1. I can stitch them together with gdalbuildvrt ...
2
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0answers
317 views

Connect two contour lines with calculated line length

Is it possible to make a plugin for QGIS like PEGGER for arcview 3.2? Problem is, how to make path over contour lines with a gradient in percent? Formula is: K= e*100/G*M ; K=10*100/0.08*10000=1.25m ...
2
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0answers
381 views

Whats the best way to create bathymetric contour lines?

I have a raster dataset with both Topographic and Bathymetric stored in it. What is the best way to create exact contours of the lake-bed? This becomes tricky when I want to make the contour for depth ...
2
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0answers
707 views

Best method to convert CSV file of lat/lon and depth data to bathymetry polygon?

I'm trying to create bathymetry polygons based on lat/long and depth data. I have tried several methods and the resulting polygons are clunky. Make XY Event Layer-->Copy Features--> Project--> ...
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0answers
171 views

Applying depth to Shapefile

Apologies if this question has been answered before. I'm digitizing a historic coastline and would like to add a single depth figure to it in order to merge it with a current contour model. Is there ...
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0answers
20 views

Blank Polygon issue using QGIS Contour Plugin

I am using QGIS with Contour plugin, want to generate filled contour polygons with user selected contour levels. However there are some errors showing blank polygons. Is it bug or is there any way to ...
1
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1answer
15 views

No Option to 'Extract' under 'Raster' tab

So I'm running an earlier version of QGIS (3.4.6, as it is supposed to be more stable I'm told) for a Field Geology course, however after installing it and adding DEM data I am unable to 'Extract>...
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0answers
30 views

Draw ellipse based on values within an attribute table

I would like to be able to draw and ellipse on a map based on values within an attributes table. At the moment I have 6 transects at a site with values based on IQI (Infaunal Quality Index) values; ...
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2answers
31 views

How to create point attribute distribution map in QGIS?

I'm working with multiple species distribution data and am looking at creating what amount to density distribution maps of those species. I have a small number of site locations (18) and only 10 ...
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0answers
41 views

QGIS create contour from DEM

I have created a DEM from points using the raster interpolation method, the TIN function, based on elevation of each point. However, when I try to create a contourline, the results show the contours ...
1
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1answer
70 views

How to extract contours from .jp2 DEM dataset?

This will be a little long-winded but I'm including all information I consider relevant. Problem: I have received a data set from a municipality that is a 3-layer LiDAR JP2 DEM and need to extract ...
1
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0answers
56 views

Conditional formatting QGIS Legend

I use QGIS to create surface plots for measurements made in the field. I use the contour plugin. I usually create ~50 contours in order to make a smooth surface. When I use print composer, I generally ...
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0answers
44 views

Using of ContourGenerate in PyQGIS

Can anyone help explain me how to use the ContourGenerate method of GDAL. The official documentation states two sets of arguments for the method, with one being ContourGenerate ( **args, ***kwargs ) ...
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1answer
47 views

A simple way to merge lines separated by a space in QGIS

In QGIS after creating contour lines by extracting them from a DEM (Extraction > Contour) and smoothing them (Line Smoothing) I noticed this situation: In order to smooth out the corners ...
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0answers
106 views

Contours generated in Leaflet losing coordinates?

I am attempting to use a JavaScript library to generate contours in a leaflet map from a point layer on the map. I have tried this approach with d3 and turf and am getting the same issue where the ...
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0answers
34 views

Calculating sink volume in R via rgrass7

I want to calculate the volume of sinks in a DEM raster in R, since I have to automatize the workflow later. Following the results of my previous question (Creating depressionless DEMs with rgrass7) I ...
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0answers
13 views

Add elevation to contour vectors using sequential numbering by drawing a line

I have several contour lines and I want to add the elevation as attribute. I found a tool in ArcGis Pro that would do exactly what I need, select the contours with a line, specify the starting value ...
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0answers
28 views

Log Scale Contouring in ArcMap?

I have a shapefile of concentration values, they range from 0 7000. I want to either contour or display these in log scale (0.1, 1, 10, 100 and 1000) what is the best way of doing this? I have about ...
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0answers
43 views

Style lines differently when intersecting a polygon

I want to give my contour lines a blue colour on glaciers (inside the polygon that shows the outlines of the glaciers) - and a brown colour everywhere else. What is the easiest way to achieve this? I ...
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0answers
73 views

Create contour lines from a WCS file in QGIS?

I am currently working on a mapping project in QGIS, and the only good DEM model I can find of SE Norway is a high-res WCS link that I have uploaded into my project. I would really like to create ...
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0answers
65 views

Uploading overlapping contours into PostgreSQL?

I've got 100+ shapefiles of contours with the following fields: class (text) altitude (double) geom (geometry) And I need to upload them into a single table in PostgreSQL. Now, I've managed to ...
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0answers
158 views

Locate roads that are close to steep slopes which risks landslides

I've a query, I'm trying to locate all the roads which are basically at risk of erosion (landslide?) when it's raining heavily for a municipality. What I have to work with is this: A shape layer ...
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0answers
642 views

Openlayers in QGIS - Errors in opening google satellite/

End goal: To put contour lines with lat&long layers from a google earth location (Rock Piles beach, HI) in QGIS. I plan to use CRS: EPSG:3760 Does the Plug in (Openlayers / QuickMapServices) ...
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0answers
530 views

Removing contour artifacts from low slope regions

I am generating contour lines from a DEM using QGIS and the python console. The process generates many small circles in regions of low slope (little black circles) that detract from the long connected ...
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0answers
126 views

QGIS/GDALDEM SLOPE Output Has Contoured Or Terraced Texture

I have been trying to greatly reduce or eliminate the contour-like texture that appears in my output from gdaldem slope. The image, below, demonstrates this textural effect. The texture of the ...
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0answers
21 views

Extracting lateral averages using ArcGIS Desktop?

I want to do the following: to calculate the lateral average value of the surface aspect of a glacier (i.e. the average along a specific contour, the greenish lines). Can someone help me or say how ...