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

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6
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1answer
145 views

Split polylines in ramps

I have a shapefile (polylines) of some roads and I want to divide the roads in ramps. Ramp = a piece of the road delimited by the top of a hill and a valley. So, pretending that you're driving in ...
1
vote
0answers
81 views

Contours generated from merged TIFs huge - much bigger than individually

I'm generating contours from four 5x5 degree SRTM DEMs in southeastern Australia. I'm using gdalwarp to reproject the DEM, then gdal_contour to generate contours. First, I generated contours for each ...
0
votes
1answer
61 views

Using Contour plugin, progress bar sticks at zero

I am using Quantum GIS 1.8.0. I have a base map sourced from OSGB Opendata VectorMap District (vector format), and that displays fine. I also have created a spreadsheet showing journey times to a ...
5
votes
1answer
1k views

Labeling contour lines in ArcMap [duplicate]

Can anybody give me advice on how to label contours as shown in Figure 2 below? I would like to be able to put the label "on" the line, which is easy enough. But I'd also like for the contour line to ...
0
votes
0answers
322 views

Continents geometry data / extracting contours of continents from country geometry

I have an ESRI Shapefile data from Natural Earth (Admin-0 Countries). I converted it to geoJSON format. There is no world or continents geometry there, only the county one. And I'd like to extract eg. ...
4
votes
1answer
290 views

Creating management zones in NDVI ortho maps with contour like lines

This question is hard to explain so if you have a possible answer I would love to hear it. I work in the precision agriculture business which heavily relies on NDVI calculations but need to create ...
0
votes
1answer
57 views

Editing symbology of contourlines with Arcpy

I just have a problem with my pythonscript. I had run the Contour-tool to generate polylines. Contour("rectExtract", "C:/fakepath/Class10.shp", 20,0) Now i want to mark the 100 meter lines in ...
12
votes
4answers
2k 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 ...
4
votes
2answers
133 views

How to create a single contour defining the boundary between sea and land

Hello! I am still learning so forgive me if my question is very simple... I am trying to create a map with ArcGIS. The area I am working on is a seasite and I found that in some parts the cells appear ...
6
votes
1answer
5k 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 ...
1
vote
0answers
418 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 ...
0
votes
0answers
123 views

QGIS 1.8.0-Lisboa error message when converting DEM to Contours

I am trying to convert a small DEM (1 megabyte) into contours. When I go to - Extraction - Contour- and run it I get the following message: "ERROR 1: CPLRealloc(): Out of memory allocating 416 ...
2
votes
2answers
2k 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 ...
1
vote
1answer
258 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
2answers
152 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?
7
votes
1answer
512 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 ...
2
votes
0answers
245 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--> ...
1
vote
2answers
622 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 ...
0
votes
1answer
447 views

Most optimal algorithm for contour correctness?

Am creating an app which correctly calculates contours from a DEM file or any height-map given to it. The correctness of the contour holding the most importance, since a person viewing the contours ...
11
votes
3answers
593 views

Contours: Interrupt contour lines beneath a elevation number

Is there a way to interrupt a contour line beneath a elevation number? Thanks!
1
vote
1answer
935 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 ...
4
votes
1answer
228 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 ...
1
vote
2answers
481 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 ...
2
votes
0answers
77 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 ...
5
votes
2answers
160 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 ...
1
vote
0answers
498 views

How to clip the contour map with the polygon using R software?

Hi I am wondering how can I create the contour lines from the discrete x, y and z dataset and then add the shapefile to cut the contour lines by polygon. I want to clip the contour map by the shape ...
3
votes
1answer
610 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 ...
7
votes
3answers
2k 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 ...
9
votes
3answers
901 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 ...
1
vote
1answer
651 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 ...
3
votes
2answers
420 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 ...
0
votes
1answer
3k views

How to convert shapefile labels to graphics (in ArcMap 10)?

I have a shapefile that represents contours. Because I have clipped the contours to the map boundary they are broken in several places. Now that I have labeled the contours there are labels that are ...
3
votes
0answers
375 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
3answers
934 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 ...
3
votes
2answers
151 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 ...
2
votes
0answers
718 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 ...
4
votes
1answer
2k 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....
3
votes
2answers
2k 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 ...
2
votes
2answers
277 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 ...
1
vote
2answers
837 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 ...
35
votes
1answer
4k 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 ...
0
votes
1answer
1k views

How to generate smooth contours from cropped raster?

I’m trying to create contours from a raster layer in QGIS. On my first attempt, I cropped my raster layer in Photoshop and reimported it, but it lost coordinate data I think. I made the contours ...
6
votes
4answers
869 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
2answers
865 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
2answers
2k 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 ...
4
votes
1answer
668 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 ...
5
votes
1answer
2k 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
3answers
1k 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
3k 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
2k 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 ...