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Questions tagged [contour]

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

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34
votes
2answers
40k views

Creating DEM from contours in QGIS?

I have a shapefile with contours and their heights. Is it possible to make a DEM from contours in QGIS without using GRASS? I found Creating DEM from contours using ArcGIS Desktop? but the answer ...
12
votes
3answers
19k views

Generating DEM from contour Shapefile using QGIS?

I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
5
votes
2answers
10k views

How to perform a slope analysis in QGIS? [duplicate]

I have contour information in the form of line features (see picture below) and I want to do a slope analysis in QGIS. Is it possible?
5
votes
2answers
8k views

Colouring areas between (vector) contours?

Is it possible to colour areas between (vector) contours without making it a DEM first? Joshdoe seems to have done so in Create filled contour map with GRASS but does not say how.
9
votes
1answer
2k views

Comparison of three contour lines

I am looking for a way to spatially quantify the difference between three contour line shapefiles. More specifically, I have two elevation rasters which I intend to create contour lines from, but ...
10
votes
3answers
22k views

How to create contour lines from point data using QGIS?

I'm using QGIS 2.4.0 and I have a shapefile of points with elevation data and X and Y coordinates. I'm using windows 7 OS. The idea is to create a contour line SHP using my point data. My question ...
20
votes
5answers
10k views

Placing elevation numbers on contours with uphill orientation and position in QGIS?

I want to orient my elevation labels uphill. Is that possible? I'm currently using the labeling tool from QGIS (not that one in layer settings). I want the labels curved and uphill oriented (and I ...
12
votes
4answers
8k views

Choosing only one contour line to label in QGIS?

Is it possible to select only one contour line for labelling? I have numerous labels for each line and I'll prefer to label only the main ones, such as 1000 m and 1500 m
11
votes
2answers
46k views

Creating DEM from contours using ArcGIS Desktop?

I have a large set of contours that I received broken down into several different subsets. I have merged most of the subsets together creating a larger set of contours in three different files. I have ...
6
votes
4answers
7k views

How to install the Python module shapely for QGIS use?

I'm using QGIS 1.8.0 on a Mac with OSX 10.6.8 (Snow Leopard). I've installed QGIS including GDAL, GSL, UNIXImageIO, Freetype, and Matplotlib all from www.kyngchaos.com. When installing the plugin ...
3
votes
1answer
7k views

Exporting QGIS contour attributes in DXF file?

I have a .tiff data file that generates contours in QGIS. I save it as .dxf. The contours don't have any attributes or data. That's bad, because I want to make a 3D landscape in Revit using the ...
2
votes
0answers
270 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 ...
5
votes
1answer
2k views

Contour lines with imported shapefile using Blender GIS - wrong Z values

I've been making experiments with Blender GIS and QGIS. I'm having problems when importing Shapefiles with contour lines, with a field for elevation (ELEVATION FROM FIELD selected when importing). I'...
1
vote
2answers
2k views

Creating fine interval contour layer from DEM using QGIS?

I would like to create 20 meter contours for a large region, roughly 120,000 square kilometers. DEM data is available as TIFF or CSV throughout this region at 0.75 arc second resolution. What tools ...
52
votes
3answers
18k views

Smoothing polygons in contour map?

Here is a contour map for which all the polygons of levels are available. Let ask how to smooth the polygons keeping all vertices preserved in their exact locations? Indeed the contour is made on ...
17
votes
5answers
25k views

Selecting contours which heights are integers?

I have a Contours Featureclass, with an interval of 0.2 meters. I wish to select only those Contours, which are at 1 m interval? I have tried using the following syntax in the 'Select by Attribute' ...
16
votes
3answers
4k views

Generating contours from DEM using GDAL?

We have just received a large set of DEMs at work and I would like to generate contours from them. The DEMs have a resolution of 1m and a size of 1kmx1km. Output from gdalinfo: Driver: AAIGrid/Arc/...
2
votes
1answer
2k views

Filling contour levels with grain (texture) using Leaflet

I created a program to draw temperature contour map of France: This is the code: library(ggplot2) library(gstat) library(sp) library(maptools) require(rgeos) library(rgdal) library(foreign) library(...
19
votes
2answers
37k views

Cropping raster layer using QGIS?

How do I crop a raster layer in QGIS? I want to make contours from a section of a layer, and including the whole layer will create far more data than I need and slow down the rendering. I have ...
6
votes
1answer
3k views

Create filled contour map with GRASS

Background I'm trying to make contour/isoline/isochrone maps to show what areas are within walking distance to schools for my pet project to help with the Safe Routes to School program. I followed ...
3
votes
1answer
3k views

Creating DEM from vector contours using GRASS and R?

I want to convert vector contours to a DEM. From other posts, I wanted to use the Grass r.surf.contours tool. Initially, I converted the vector contour layer to a rasterized contours using the ...
5
votes
2answers
2k views

Creating contours for specific elevations

Input data: 1. an SRTM raster. 2. Point file of peaks. -Attributes contain ID, x, y, z and the elevation at which the peak is completely isolated from a neighboring peak. The output I want is a line/...
4
votes
2answers
4k views

Simplify Raster Contours ArcGIS 10

Does anybody know a way to simplify a number of contour polylines derived from a raster dataset? I need to generate a map that shows contour polylines at relatively small scale. With the contour ...
4
votes
2answers
770 views

95 percent volume contour

I generated, from point data, a kernel density map using GRASS, and I would like to identify the 95% volume contour in it. Is it possible in GRASS?
3
votes
1answer
133 views

Rasterizing Shapefiles onto TIFF loses style

I have two contour shapefiles, one for 2ft and one for 10ft contours. I want to put these on a TIFF file I have of the aerial. I achieved this by going to Raster > Conversion > Rasterize and using ...
3
votes
1answer
401 views

SVY and QDC files from Quickdraw Contours in QGIS

I am trying to view data collected from a Garmin sonar unit in QGIS. The data on the Fishfinder shows or creates the contours but I can't seem to find a way to convert it to a format that QGIS can "...
2
votes
3answers
2k views

Generating raster from isolines using SAGA or ArcGIS?

I have a vector dataset of mean annual precipitation polylines, and I would like to generate a raster from them. I'm not sure the best way to go about it. ArcGIS has the Polyline to Raster tool but ...
32
votes
6answers
5k views

How to interrupt contour lines beneath elevation labels (instead of using label buffers)?

Is there a way to interrupt a contour line beneath an elevation label?
13
votes
2answers
2k views

What is the smallest contour interval possible when derived from a DTM?

I am converting a 2m DTM to contours, and would like to have the smallest interval possible. Is there a theoretical limit, or even a rule of thumb for defining contour intervals based on the ...
10
votes
1answer
1k views

Generating DEM from isolines and spot heights using GRASS?

I have two shape files containing height information of a certain area and I need to create a raster DEM with GRASS using them. file 1 consists of height information in contours (isolines) file 2 ...
10
votes
4answers
2k views

How to automatically plot intermediate contours with QGIS, GRASS GIS or SAGA GIS?

I'm mapping a steep mountain range. My main contour interval is 50 m and my intermediate contour interval is 10 m. In steep areas, the interval of 10 m is too small, so I need to leave ...
8
votes
3answers
5k views

How to extract slope from topographic raster map? [duplicate]

I am working on a project for a machine learning class wherein I extract features from a topographic raster map and then classify the traversability of the terrain. One of the features I need to ...
7
votes
2answers
3k views

How to Create Contours for Zonation

I'm still new in the world of GIS. I'm currently doing some zonation with "test points." Each has its own coordinates and "P" value. I want to make contours of these data, to divide the whole area ...
11
votes
5answers
4k views

Measuring straightness of a curve segment (represented as a polyline)

I'm working on an automatic elevation contour labeling algorithm and one of the factors that I want to take into account when deciding the positions of labels is how "straight" a particular segment of ...
6
votes
1answer
6k views

QGIS contours smoothing and cleaning

Trying to utilize the contour extraction QGIS tool but having trouble creating smoothed contours. The smooth, generalize, and dissolve tools have not worked for me. Also the plugin for contours ...
4
votes
2answers
21k views

Detailed Bathymetric/Bathymetry contour data (0-200M)

I am looking for free Bathymetric contour data in shapefile format for depths between 0-200 meters for North America. I prefer contours at 10 meter increments, but will take whatever I can get. I ...
4
votes
2answers
3k views

Is it possible to give 2d contours a Z-height from their attribute table in QGIS? (Or ArcGIS?)

I have a contour data file downloaded from UK Ordnance Survey, which gives 2d contours of an area in gml format (also supplied in .shp format) with the heights of each contour attached to the ...
4
votes
1answer
3k views

How to create a Digital Elevation Model using GRASS

How to create a DEM starting from layers shapefile "contour lines" and "shares"? Which module of GRASS do I need to use?
5
votes
1answer
2k views

How to create contours from smoothed DEM instead of using Terrain to Raster?

I'm fairly new to working with lidar and have been assigned the task of creating 2ft contours for the entire county using USGS-provided lidar tiles. Is there a significant difference in the accuracy ...
5
votes
1answer
637 views

How to find depressions (sinks) and hills based on contour line features

I have contour lines (interval 0.1m), derived from a DEM (1m). I used the thinning ratio to find only features, which are like circles. I've imported these features into a Spatialite database. The ...
4
votes
3answers
2k views

Exporting contour lines from CAD to GIS

I've been using GIS softwares in the past few years by I'm new using AutoCAD. Well, I have contour lines in AutoCAD and I want to export it into QGIS (I also have access to ArcMAP). I saved as .dxf ...
4
votes
4answers
10k views

Symbology of contour lines in ArcMap

I have contour lines with height values from 0 to 1030 (sorted by height 110, 115, 120, 125). Values with in-between number (like 5, 15, 115, 135...) should be grouped and colored with same color, and ...
4
votes
1answer
2k views

Generating contour lines and filled contours from points

I am trying to create contour lines and filled contours from a shapefile of height points using the contour plug in (have tried other tools but with no success). The data is sourced from the UK ...
3
votes
1answer
2k views

How to get smooth contours from points or IDW raster in QGIS

Hello I'm an artist trying different ways of drawing contours in QGIS using points with income values. I've been able to import a shp file with the data, create a layer with centroids of the census ...
3
votes
2answers
3k views

Exporting USGS contour line shapefile to DWG or DXF?

How do I assign the Z value based on the Elevation attribute using ArcGIS 10.1 for Desktop? I've been messing with this for an hour or two now and every time the exported DWG has ZERO for z value for ...
3
votes
4answers
7k views

How to clean up contours?

I have .dxf file with contour lines representing elevation. But this contours are too "ugly" and elevation model looks just bad. As you can see on image, contours are not continuous... Is there any ...
2
votes
2answers
2k views

Interpolation of contours (from one “main-contour-shapefile”)

I calculated, that the best and smallest possible äquidistance (equidistant) for my map is 30m. After I generalized my DHM, I extracted contours of a interval of 30m and smoothed them. Now I have my "...
2
votes
2answers
638 views

Losing large portions of elevation contours from QGIS to PDF

Please forgive me as I'm new to GIS and all this might be a silly question, the wrong place for this question, or a hack way of going about what I'm getting at. So any suggestions on better practice ...
2
votes
1answer
656 views

Checking if z values of contour lines are correct using ArcGIS Desktop?

What is the easiest way to check if z values of contour lines are correct in ArcGIS? I need just to look at the values, to see if equidistance between them is correct and unchanged.
1
vote
2answers
410 views

Problem with contour lines thickness in bigger zoom levels

I'm a beginner user of GDAL tools. I'd like to rasterize contour lines into Tiff file (for example such region: N47E006), everything works for quite small zoom levels e.g. 10... but the problem is ...