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

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36 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 ...
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89 views

Is it possible to add intermediate contour values automatically in QGIS?

Let me explain the scenario. We have 100's of elevation contour shp files. In each file, only the 10th contour line has values (200, 450, 700, etc..). We have to attribute values for all the ...
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359 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 ...
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495 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 ...
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1k 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 ...
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45 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 ...
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52 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. ...
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76 views

Acquiring Digital Elevation Models for Argentina from commercial providers

I'm interested in obtaining Digital Elevation Models for areas in the 20,000 acre range, as I use them to create contour maps for agriculture. The USGS Earth Explorer has a wonderful free DEM ...
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55 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 ...
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204 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 ...
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111 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 ...
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193 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 ...
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383 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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106 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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9 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 ...
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13 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 ...
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50 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 ...
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24 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 ...
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21 views

Contouring with cliff faces in ArcGIS for Desktop?

I am trying to create some contour lines that are around cliff faces. What is the best way to create contour lines that are effected by cliff faces and is there a way to automatically draw the cliff ...
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34 views

how can I make contour lines out of points with different heigths?

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 ...
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48 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 ...
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70 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 ...
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32 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 ...
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31 views

Clip Categorized Polygon with another Polygon

Ok, so first off, I've gone through the forum, and looked at every post that sounds similar. They have all been solved, but none of the solutions have worked for me. Basically, I have created a ...
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115 views

How to create contours from an IDW raster

I'm new to QGIS and am trying to create vector contours from this IDW raster. I followed Ujaval Gandhi's "Interpolating Point Data" tutorial step by step but am not getting the same results for step ...
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94 views

Import ARCGIS web dataset contours into Sketchup

My local council has online ARCGIS data sources including 1m elevation contours. I am trying to import these into a sandbox terrain model in sketchup to do some landscape planning. Conceptually I ...
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89 views

Isolate contour line with a minimum number of points (to eliminate small polygons) with ArcGIS

I extracted a single contour line (altitude 3660 m) with ArcGIS. How can I eliminate small polygons ? I know how to do it with a GRASS command (generate contour lines) which simply asks for a minimum ...
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63 views

QGIS creating contour lines ERROR 1 CPLRealloc() out of memory allocationg 416 bytes

When i try to create contour lines from raster (tiff file) in QGIS 2.6.0 Brighton i get the following message: I thought it could be irregular size of raster that causes error so i clipped it in ...
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61 views

How to make input data matrix in flowmapper

I have problem with using flowmapper. I'm confused, how do I enter a text record? Can you give me an example of an appropriate text file? I've been doing interpolation and made a contour of the ground ...
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79 views

Regenerate contour lost parts

I have some countour datasets where some parts were cut by labels, like this: Can these parts be regenerated? What I've tried is to create a straigth line between the dangling ends, but there are ...
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16 views

Where can I find the format specification for LSLIFF data?

I have an LSLIFF file which should contain some map contour data, and I want to write a renderer for it, but to do that I need to understand the file format. A preliminary search has not turned up ...
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142 views

Contour command in Spatial Ecology's GME

Has anyone been successful using the contour command from GME (Geospatial Modelling Environment)? I'm trying to create contours out of a DEM. I know you can do it in ArcGIS with 3D or Spatial Analyst ...
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94 views

How to define disturbed/clipped contours elevation for Volume Polygon?

I want to calculate surface volume for different layer on TIN surface. I am working on an area in Norway which is 1 km * 1 km. The aim is to calculate surface volume of different imaginary elevation. ...
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209 views

Error when labelling kriging result (contour) - the input layer is not valid

I've finished kriging, creating a contour-map, representing groundwater-height in my area. By a reason I don't know, it isn't possible to label my results. Neither can I export my data to vectors: ...
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94 views

Trouble intersecting a polyline and contours (Hack index / stream length gradient index)

Working on creating polylines for measurement using SL index (hack index). So far I have the main trunk of a stream, and contours at 10m. What I am trying to do is a) get the elevation at each ...
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42 views

Creating contours from partial data set

Is it possible to create contour lines based on part of the points and not the entire dataset?
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183 views

How to improve creating contours for super-high unnatural mountains?

in a current project I am working on we are not mapping the actual height of a landscape rather mapping the interest which specific stakeholders have in parts of the region. So, what we did was the ...
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104 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 ...
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119 views

Unsplit lines based on length and attributes

I have a contour dilemma. Using Microstation, 1-ft contours have been made on a til-by-tile basis in our project. These DGNs were imported into a GDB, so the polylines have already been merged ...
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1k 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 ...
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897 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 ...
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42 views

Drawing contour with python QGIS?

I have one point layer and one contour layer and I was trying to draw a line around one contour, making a circle but not a uniform one, it has to have an irregular shape. I cannot find a tool that ...
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24 views

Contouring and rendering bathymetric & other attributes in QGIS

I wish to visualise (2d & 3D) and contour point sampled bathymetric and other associated attribute data (biovolume and bottom hardness) in QGIS. The source data files are CSV files consist of lat/...
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13 views

Converting polygons to contours based on value in polygon table

I have the following and data and have been asked for a map that shows the same data set but displayed as contours. Each polygon has a value in it's table called "count". The "count" field is used to ...
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53 views

Calculate z value for contour line from x,y in dxf file

I am working on a project about route chart and cross section generation for hiking with Hong Kong Lands Department's Digital Topographic Map B5000 (sample). Height information are required for this ...
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0answers
54 views

Terrain elevation in QGIS

How can I get started with creating a map with elevation just like this one: Basically I need a map that looks like the one above. Can someone tell me where can I get the data, and how do I process ...
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86 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 ...
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145 views

Difference in contour lines derived from IDW and TIN in ArcGIS for Desktop?

I would like to know the difference between contour lines derived from IDW and contour lines derived from TIN. I have collected GPS points, and I know the elevations are not accurate but it is within ...
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152 views

Merging contour lines generated by gridded data

I have a set of gridded data, which I have used to generate contour lines based on separate values in the data. In the example provided the contour lines shown correlation coefficients. The contours ...
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69 views

ContourList error

i use ArcGIS Desktop 10.1 in Windows 7 and develop with visual studio 2010, .net v3.5. This is a quite strange problem. I have a Console Application that calls this simple function: public void ...