Contour maps depict spatially-varying values, such as elevation, by means of curves of equal value.
27
votes
1answer
2k views
How to smooth the polygons in a 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 ...
13
votes
1answer
710 views
Good practice for generating contours from a DEM
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: ...
9
votes
5answers
651 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 ...
9
votes
3answers
401 views
What are common methods for converting raster digital elevation data to vector contours?
In researching this I have found many references to the opposite, creating elevation data from contours, but nothing regarding contour creation. Preferably, I am looking for open source solutions like ...
9
votes
4answers
880 views
How to place elevation numbers on contours with uphill orientation and position?
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 ...
9
votes
3answers
245 views
Contours: Interrupt contour lines beneath a elevation number
Is there a way to interrupt a contour line beneath a elevation number?
Thanks!
7
votes
2answers
1k 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 ...
7
votes
2answers
613 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 ...
7
votes
4answers
3k views
Is it possible to make a DEM from contours in QGIS?
Is it possible to make a DEM from contours in QGIS? I have a shp file (contours) and their heights, can I use QGIS for produce a DEM without using GRASS? I find this creating a dem from contours but ...
6
votes
3answers
583 views
How to extract slope from topographic raster map?
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 ...
5
votes
1answer
102 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 ...
5
votes
2answers
93 views
Using field calculator to delete specific contours
I have 3 contour shapefiles with 25m, 50m and 100m equidistance. Now I want to delete in the 25m-shp-file every **50m and **00m contour and in the 50m-shp-file every **00 contour. How can I show them ...
4
votes
4answers
2k 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
4answers
452 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 ...
4
votes
1answer
886 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 ...
4
votes
1answer
369 views
Obtaining a contour as a single polygon in ArcGIS?
I have a DEM that I want to retrieve a single contour polygon from at a given elevation. I can use the Contour tool to obtain a series of polylines at a given elevation by setting the contour interval ...
4
votes
1answer
71 views
How to use -lco options in gdal_contour?
I'm trying to create contours from geotiff raster with gdal_contour. My output format is Postgresql and I would like to ovewrite the existing table.
When I do:
gdal_contour -a 1 -f PostgreSQL -i 50 ...
4
votes
2answers
1k 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
1answer
462 views
TIN Creation from 3D Contour File
I'm currently trying to import a 3D contour file into a Quantum GIS project. My question is, how can I export the DXF file from Microstation with height information? I already have imported it to the ...
3
votes
2answers
1k views
Java Contour Algorithm
Does anyone know if there is an open source project in Java that will take a set of (x, y, z) points and create a contour map for Google Maps/Earth?
There does not seem to be a good contouring ...
3
votes
2answers
65 views
Finding depression with contour lines
How can I find depression contour lines?
I already have find depressions via Fill-method, but now I try to detect them by using the contour lines. anyone have an idea ?
3
votes
2answers
185 views
Exporting a USGS contour line shapefile to DWG or DXF
how do i assign the Z value based on the Elevation attribute? Using ArcGIS 10.1?
I've been messing with this for an hour or two now and every time the exported DWG has ZERO for z value for all lines.
...
3
votes
2answers
141 views
Selecting a suitable GIS for my project
I need to develop a web-based map using existing shape files. Using the web-map, we must be able to select a region and produce contours for that selected region. Can any one suggest the best open ...
3
votes
1answer
2k views
How to crop raster layer?
Can anyone tell me how to 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 ...
3
votes
3answers
704 views
How to position contour labels in Maplex above the line?
I would like to utilize the "contour placement" options of "Uphill alignment" and "Laddering" while positioning the label above the contour not over it. This does not seem to be an option under the ...
3
votes
2answers
2k views
How to create shaded relief in ArcGIS?
How can I create shaded relief from contour lines (.shp format)? I see Hillshade in ArcToolbox, but it asks for a raster file. I have ArcGIS 10.0.
3
votes
2answers
808 views
ArcGIS 10: How to clip point buffer to features in another layer?
I'm on a steep learnig curve here, so aplogies if my question is a one-banana problem.
In ArcGIS 10 I have a contour layer that was generated from an ESR ASCII raster file (batyhmetry of the South ...
3
votes
0answers
224 views
How to contour irregular point data for overlay on Google maps?
I am having some serious trouble finding a solution to fit my current needs. I am attempting to create contour maps from irregularly spaced point-data on the fly to overlay on a Google map. I have ...
2
votes
1answer
543 views
How to create a Digital Elevation Model
How to create a DEM starting from layers shapefile "contour lines" and "shares"?
which module of GRASS I need to use?
thanks for yours responses....
2
votes
2answers
293 views
Easiest way to check if z values of contour lines are correct
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.
2
votes
2answers
488 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 ...
2
votes
3answers
382 views
Generate raster from isolines
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 ...
2
votes
2answers
170 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
296 views
Problem with generating contour lines and filled contours
I am trying to create contour lines and filled contours from a shape file of height points using the contour plug in (have tried other tools but with no success).
The data is sourced from the UK ...
2
votes
0answers
90 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
votes
0answers
50 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 ...
2
votes
1answer
209 views
Contour Lines Raster Extraction
I've been playing with Mapbox's blog post about converting heat maps to contour lines, and I'm stuck at the extraction part of this process.
I used the CSV plugin to create a vector layer of points, ...
2
votes
0answers
425 views
Dynamic Contour generation and project on google maps
Is it possible to generate contour map layer at runtime and overlap or project on google maps.
I am using google map api v3 and want to generate contour map layer using data from sql server and ...
1
vote
2answers
53 views
Is it possible to colour areas between (vector) contours?
...without making it a DEM first?
Joshdoe seems to have done so ("Styled in QGis") here but doesn't say how.
Thanks!
1
vote
1answer
401 views
Help with technique to create contours from ASTER DEM in Phnom Penh, Cambodia
I have the ASTER version 2 DEM of Cambodia. I want to use it to create 1m contours of Phnom Penh, Cambodia. If anyone has this already please let me know. Now, onto the problems:
I am using ArcGIS ...
1
vote
1answer
193 views
How to install the Python module Shapely.geometry 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;
Matplotlib
all from www.kyngchaos.com/
When installing the plugin ...
1
vote
2answers
444 views
Interpolation of contours (from one “main-contour-shapefile”)
I calculated, that the best and smalest possible äquidistance (equidistant) for my map is 30m. After I generlized my DHM, I extracted contours of a intervall of 30m and smoothed them. Now I have my ...
1
vote
1answer
49 views
Extraction of contour lines starting from 0 elevation
I need your help regarding extraction of contour lines in QGIS. I am new to QGIS (in GIS actually).
I followed the tutorials on extracting contour lines from DEM (which I downloaded from cgiar.srtm) ...
1
vote
1answer
75 views
QGIS contour lines shapefile to DEM help
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, ...
1
vote
2answers
40 views
contour lines from point shape attribute
I have a point shape file and one of the attribute refers to the altitude.
Is is possible to obtain a contour lines shape file in GRASS?
1
vote
2answers
135 views
Problem creating TIN from multiple contour shapefiles with ArcGIS 9.3 Spatial Analyst
I have about 20 shapefiles that contain contours lines, and I'm trying to convert them to one TIN using Spatial Analyst in ArcGIS 9.3. I included all of the SHP's as input to generate a TIN, but it ...
1
vote
2answers
149 views
How to specify gdal_contour output format as postgresql table?
I want to generate contours with gdal_contour command.
It generates an output as shapefile by default.
I want this utility to output a postgresql (postgis) table.
The documentation says there is a -f ...
1
vote
2answers
312 views
How to batch process (100s) of interpolations in QGIS or other open source software programs?
Is there an efficient way to run 100s of interpolations in QGIS or other open source software programs?
I have groundwater contamination data collected from monitoring wells at about 800 different ...
1
vote
1answer
556 views
Calculate the distance between two contours
I have two contour polylines (single shapefile) and I would like to calculate the mean, min and max distances between the two lines. Is there a function in ArcMap 10 (ArcInfo license, incl. Spatial ...
1
vote
0answers
58 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 ...
