Tagged Questions

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

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30 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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0answers
94 views

Google Maps basemap not showing up when KML file added as a vector layer in QGIS - only point markers appear

I am trying to make a basic XYZ contour plot in QGIS 1.8.0 (longitude, latitude, depth in an excel file) and can't get past the first step of adding a basemap in QGIS. I've tried using the Open ...
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0answers
133 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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0answers
53 views

How can i get the contour (boundry line) of a feature collection

I have all parcels of given locality as a FeatureCollection. Each parcel is a Feature with a MultiPolygon outlinine the boundry of that parcel. I would like to get a Multipolygon that has the shape ...
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0answers
101 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 ...
4
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1answer
99 views

Suggestions for vector format for contour map

I've been trying to create a contour map of a DEM and I've been running into some technical problems. I want to avoid artifacts, so I'm using a DEM of the entire area. This means the size is rather ...
4
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1answer
475 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 ...
2
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1answer
476 views

How do I run the nvis tool in QGIS GRASS?

I am trying to follow this workflow: [How to generate a DEM from a countour Shapefile?] and it's running fine, and when I hit view output or view results I end up with a flat raster with shading ...
3
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1answer
284 views

How to create DEM from contours without ArcGIS Spatial Analyst licence?

I'm trying to create a 3d DEM/DTM from a flat contour shapefile which has height data attached to each contour, but I'm not sure how to do this? I've found this post, on creating a dem from contours ...
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0answers
30 views

Find area that it's in one GeoJSON file but not the other

I have two GeoJSON files, A and B. The features in A contain everything in B, and more (they're contour lines, and A is a lower elevation). How can I get the difference between the two files? As ...
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2answers
173 views

How to derive point height from contour data?

I got vector layer that represents height over sea level. Then, I also have different vector layers. Is there any good way of using QGiS or things related to calculate sea level for those points? ...
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0answers
19 views

How to create single contour shapefile from a contour shapefile? [duplicate]

Is there a way to create single contour shapefiles from a main contour shapefile. The main shapefile has quite a few contours and I need to isolate them and create individual files by elevation. ...
3
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2answers
189 views

How to connect contour lines from two different sources?

How to connect contour lines from two different sources (LiDAR & Photogarametry) in order to obtain continuous and uniform contour lines layer ? how can i interpolate them together ? How can i ...
0
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1answer
42 views

file type needed to add layer containing contour lines

What file format is usable/recognized by qgis to add contour lines to a map? I'm working with Linux Mint 15, and qgis 1.7.5
4
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1answer
717 views

How do I add Garmin .img files to QGIS?

I downloaded 10 .img files from garmin.openstreetmap.nl which are supposed to contain the topo tiles for the area I would like to add in qgis. I've been unable to find any instructions on how to use ...
3
votes
2answers
511 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 ...
1
vote
1answer
123 views

Computing altitude from contour table - slow ST_Dwithin query

I am using PostgreSQL 9.2/PostGIS 2.0. I have a table of house addresses and a table of contour lines which are as follows: address_list house_id | geom (point, 4283) ---------+--------- 1 | ...
2
votes
1answer
157 views

ASTER GDEM v2 coastline generation?

I try to generate world coastline 1:30000 from ASTER's DEM with: gdal_contour -a ELEVATION -fl 0 But above produce some of missing coastlines. Whats happening? Is it cliffy shore? How would you ...
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0answers
356 views

QGIS Contour plugin - contours from points

With QGIS 2.01, the plugin Contour is not available. Anyone have another method to create contours from point / shapefile source, where the points are not a grid?
3
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1answer
243 views

Creating Contours from a Classified Raster - ArcGIS

I have a group of classified raster files, showing point densities at 3 intervals. I want to create contour lines based on this data at these same intervals. I'm guessing this should be fairly easy, ...
6
votes
1answer
137 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
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0answers
77 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
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1answer
60 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 ...
3
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2answers
276 views

Converting points to Percentage Volume Contours using ArcGIS 10.1 for Desktop?

I need to convert about 100 different sets of points into percentage volume contours. These are currently in vector format. What would be the most efficient way to do this? I'd rather do it in ArcGIS ...
1
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0answers
95 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 ...
1
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1answer
535 views

How to create filled contour lines in QGIS?

How can I create contour lines that are filled with a graduated symbol usinq QGIS? In ArcGIS for Desktop I can do this. What about in QGIS?
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1answer
102 views

Jagged Contours ArcGIS

A general question when working with contours, do jagged lines indicate more spatial variance in a data set?
5
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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 ...
7
votes
1answer
391 views

Creating contours with meaningful values from point data

I recently obtained a CSV containing the locations of all recorded bicycle accidents in Boston over the past few years. As an avid cyclist, I'd like to create a simple contour map that draws attention ...
0
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0answers
305 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
269 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
436 views

Label Features with Arcpy

I had run the contour tool in my script to generate polylines. Contour("rectExtract", "C:/fakepath/Class1.shp", 50,0) Now I want to label the polylines with the contour-value. If I execute this ...
0
votes
1answer
56 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 ...
1
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1answer
39 views

How to export Std Dev from Raster Dataset of DEM to classify current extent and execute Contour Tool with Python?

I want to create Countour Lines for a DEM which are based on a "STD dev" classificaion. My problem is that the "Std dev" is exported in an unknown type instead of a String. So the classifacation for ...
4
votes
2answers
125 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 ...
1
vote
2answers
333 views

How to create a raster (topo to raster) with non-rectangular shape?

I'm using Arcmap 10, I need to create a raster from contour lines. These contour lines were clipped out with a certain shape with the purpose to modify them only within that shape and then create the ...
0
votes
0answers
116 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 ...
1
vote
1answer
573 views

Import SketchUp created KML contour lines model to QGIS

There's a neat trick to create contour lines based on the GE 3D terrain using Sketch-Up. The resulting KML however is a model I have looked at ways of importing KML layers to QGIS, like it was ...
3
votes
2answers
1k 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.
1
vote
1answer
233 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
0answers
379 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 ...
4
votes
2answers
3k views

How to generate a DEM from a contour Shapefile?

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
138 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?
3
votes
1answer
455 views

How calculate areas between certain contour lines in qgis?

Sorry for asking a question which I found in similar ways already here, but I am trying this for days and just got no result: How do I calculate the area between certain contour lines (e.g. 0-800, ...
5
votes
2answers
434 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 ?
7
votes
1answer
453 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
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 ...
2
votes
0answers
238 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
561 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 ...
3
votes
2answers
1k 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 ...