Questions tagged [contour]

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

4
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0answers
312 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 ...
3
votes
0answers
185 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 ...
3
votes
0answers
217 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 ...
3
votes
0answers
156 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?
3
votes
0answers
145 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
votes
0answers
337 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
votes
0answers
946 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
votes
0answers
298 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
66 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
votes
0answers
69 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
votes
0answers
1k views

Smoothing the contour line in Python?

I used the NCEP 2.5 degree*2.5 degree data to plot the 850 mb wind field and heights. But, I didn't know how to smooth the contour line. Scipy.ndimage.zoom didn't work well and some details are missed....
2
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0answers
35 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
votes
0answers
342 views

Extracting xyz data from .dxf after conversion to shapefile in QGIS

I have both a .dwg and derived .dxf data set originally generated in AutoCAD Civil 3D. It appears as a series of triangles which cannot be exploded but each individual triangle does have xyz ...
2
votes
0answers
301 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
votes
0answers
134 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
votes
0answers
192 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
votes
0answers
106 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
votes
0answers
531 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
votes
0answers
254 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
votes
0answers
357 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
628 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--> ...
2
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0answers
157 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 ...
1
vote
0answers
32 views

Missing Contours when extracted from DEM in QGIS?

I used QGIS Raster->Extraction->Contour tool to extract contours at 1m interval from a virtual raster. The virtual raster was built using around 100 tiles in ASC format that represented a 1m DEM. ...
1
vote
0answers
59 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 ...
1
vote
0answers
147 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 ...
1
vote
0answers
38 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 ...
1
vote
0answers
51 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 ...
1
vote
0answers
60 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 ...
1
vote
0answers
156 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 ...
1
vote
0answers
565 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) ...
1
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0answers
255 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 ...
1
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0answers
87 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 ...
1
vote
0answers
20 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 ...
1
vote
0answers
26 views

Methods to differentiate between terrain

I am not specialized in GIS. I have some moisture contour maps, I want to compare each pair to trace the changes between either in a numeric way. I tried to get the mathematical difference between ...
1
vote
0answers
71 views

How to create a line through contours?

I am using QGIS 2.18.14. I want to create line through contour lines with fixed segments, automatically. I already tried manually with 'Advanced Digitizing Tools'. It works fine but too slow. The ...
1
vote
0answers
50 views

How to make rules so two QGIS contour maps don't cross

I'm creating multiple contour maps stacked on one another over one geographical area based on the depths of various attributes. In some cases, given the mass of data and occasional inaccurate data, ...
1
vote
0answers
195 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 ...
1
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0answers
161 views

How to merge USGS contour data from files into state?

Long story short, I'm looking to take 1/3 arc-second 1x1 degree contour shapefiles from the USGS National Map Viewer and transform that into a contoured map of a particular state, but am encountering ...
1
vote
0answers
160 views

Solutions for generating grade/slope estimate heatmaps from a topography contour layer

Given a shapefile layer of 5-ft interval topography contour lines overlaid on google earth, I could, using the Ruler tool and some simple arithmetic, calculate average percentage grade numbers for a ...
1
vote
0answers
253 views

QGIS isolines from points and lines

I'm getting started with QGIS and I want to use survey data to generate isolines. Contour plugin works well except when surveyed area has linear details (say, a road) that are elevated relative to the ...
1
vote
0answers
72 views

Problem with contour line

I have a problem when I create a contour line from DEM, it's become sharp and not correct ( image attached ) . DEM cell size = 5m Contour interval = 5m
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0answers
87 views

How to align 3D contour file, aerial imagery and design drawings from engineers in microstation v8i series 3.

I am looking to align a 3D contour dgn file with the design drawings from an engineer in microstation. Then align an orthorectified aerial image (Scale 1:10 000) to the contour file and design ...
1
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0answers
15 views

Any way to remove 2 point polylines in bulk?

QGIS: I have successfully created contours from a DEM and subsequently cleaned them up using generalizer tools in the following order: 1. Vertex reduction 2. McMinimans distance algorithm. The ...
1
vote
0answers
37 views

Converting Labels to Annotations moves position of labels

Why are my contour line labels moving after I convert them to annotations? I am using Maplex to place them. But if they still move after I converte them to annotations, the whole maplex placing ...
1
vote
0answers
33 views

Faulty altitude point between contours

I have point(picket?) between 2 contour lines with even number altitudes. Now i got these new 5 meters steps contour in between. As you see, this point between red lines was OK, but now that this 175 ...
1
vote
0answers
108 views

Making contour lines out of points with different heights using QGIS?

I have different points in a polygon. The points have the attribute "depth" and either have 0m, 2m or 4m depth. My task is now to create some sort of contour lines with the points with the same depth ...
1
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0answers
77 views

GPS point elevation vs Contours layer elevation

I have some survey grade GPS points whose elevation is approx 55 feet lower than my contours layer elevations. I am using 1 ft contours and comparing point elevations with contours in the same ...
1
vote
0answers
140 views

How to extract area information from a raster based on a DEM or contour lines

I have a raster representing the distribution of a specific land cover type - the raster values are 1 for where the land cover type is present and 0 where it isn't. I also have a DEM with 5m ...
1
vote
0answers
146 views

Contours from delaunay triangles

I have generated a delaunay polygon file that represents terrain data. Is there a way I can produce contours from the polygon file? I know I can convert the polygon to an Esri TIN, and then produce ...