Questions tagged [simplify]

A type of cartographic generalization in which the important characteristics of features are determined and unwanted detail is eliminated to retain clarity on a map whose scale has been reduced.

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52 views

Simplify geometry of multiple features without losing shape [duplicate]

I am simplifying administrative boundaries using a high simplify tolerance (which is my intention so as to get a minimalist appearance). However, after simplification, the borders of the regions no ...
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1answer
423 views

How to use GRASS Generalize to reduce GADM data size to 1/5 preserving topology?

The GADM is a great resource from global boundaries of countries, states and municipalities. The amount of detail is suitable for many analyses but when it comes to mapping or displaying it is often ...
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1answer
496 views

Simplify networks from OSM in qgis

I want to make something like in this question in QGIS. In ArcGIS there is available Make Divided Roads plugin. Is there easy way to make the same job in QGIS?
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1answer
3k views

Advanced Digitizing Error CAD tools are not enabled for the current map layer

Using QGIS 2.8.4. I want to use the Simplify function so turn on the Advanced Digitizing menu. The panel displays an error "CAD tools are not enabled for the current map layer" and the error message ...
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1answer
191 views

How to delete vertices with the same direction

I have feature with a big amount of vertices. But these vertices are totally useless and make Qgis editing too slow. Lets look on image with example: These vertices inside of black line I want to ...
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0answers
2k views

Algorithm to simplify a Polygon/Series of Points to a given number of Points

I have a polygon (or let's call it just a series of points). I want to simplify it (reduce the amount of points) to a given number of points. Currently I use Douglas Peucker and try to guess the ...
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0answers
296 views

Filtering Small Areas of Shapefiles Using R

I'm trying to use the method proposed by the @ialm in the Question "How to speed up the plotting of polygons in R?" There, he loads the maps using getData from the raster package, I tested and it ...
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0answers
766 views

How to calculate tolerance for TopologyPreservingSimplifier in JTS?

I am trying to simplify some areal geometries (POLYGON\MULTIPOLYGON) using JTS's TopologyPreservingSimplifier.simplify(Geometry geom, double distanceTolerance) From the JavaDoc: void ...
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1answer
540 views

Generalizing (simplifying) polygon shapefile or feature class in ArcMap while preserving topology?

I came across Generalizing polygon file while maintaining topology in QGIS? which asks for a QGIS solution to my exact question. I'm trying to do this in ArcMap. I start with a polygon shapefile (...
2
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1answer
779 views

Using Chaiken Method parameters for smoothing polygon vectors in QGIS [duplicate]

I've been trying to smooth a huge polygon, that is result of a segmentation export. I'd like to know what's the best parameters to use Chaiken Method to get smooth curved boundaries on QGIS 2.14. I ...
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0answers
118 views

How can I use ST_Contains/ST_Overlaps with non-simple lines?

Following the SQL of the accepted answer to How to get smallest line segments from intersection + difference of multiple overlapping lines? copied below. I'm having some difficulties assign the ids of ...
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0answers
787 views

ogr2ogr (or other) simplification of polygons with shared boundaries

I am trying to simplify a collection of 100,000 or so polygons containing nearly 4 million vertices. The data is stored in a 2GB shapefile so there is no explicit representation of the topology ...
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3answers
5k views

Simplify geometries but keep them contiguous

I have several detailed contiguous areas. I need to turn each one into KML, but when I do so, the end result is too large (in terms of memory). Using PostGIS I need to simplify these geometries but ...
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2answers
70 views

How to find fluctuant parts in a trajectory

I am currently doing an assignment on how to compress a trajectory. Given a trajectory T1 in figure 1, and I want to get a compressed version as T2. For segments p0~p3 and p6~p9 in T2, I can obtain ...
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1answer
625 views

Can I simplify geometry on the fly in a ArcGIS JavaScript map viewer?

We've got a polygon feature class of parcels around a lake boundary that is incredibly accurate. The editor did a really thorough job of following all the inlets and meanders along the edge. From just ...
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1answer
237 views

Simplify shapefiles [closed]

I've shapefiles with me and I want to de-code those file and want to build a custom map. Could someone let me know how can I do that with out using Python code.
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2answers
2k views

Simplify/generalize Polygons and keep topology of different layers PostGIS/QGIS

i have some polygons of a country, states, districts, communities and i want to simplify the geometry. i already simplified the geometry of each layer but afterwards of course it doesnt fit with the ...
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0answers
109 views

Resolve Building Conflicts - the open source way?

In ArcGIS there is a tool called Resolve Building Conflicts and I'd like to achieve the same using only open source tools (QGIS, GDAL etc), preferably on Mac OS instead. In the long run I'm trying to ...
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0answers
124 views

C/C++ function to return minimum set of points required to represent a geometric shape

I am looking for a method from Grass, GEOS, or similar that will delete those points in a geometry which do not affect its shape. Example 1 +----+----+ p0 p1 p2 p1 can be deleted without ...
3
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1answer
115 views

Generalizing exact location of certain data points using Carto CSS?

I am dealing with some sensitive data for which providing a high resolution of accuracy of the location would be detrimental. However, the general location is not sensitive and useful to share. I ...
2
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1answer
335 views

PostGIS: How to dissolve vector data

I have a few scenarios where I need to dissolve vector data, and I'm wondering how to do this using PostGIS. What would the queries look like to perform these operations? Below I'll describe the ...
2
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1answer
116 views

QGIS simplify geometries shifts polygons north

I'm trying to simplify polygons in a shapefile using the "Simplify Geometries" tool in QGIS 2.10 (Pisa). This works as expected, except for one strange effect: the resulting features (shown in green) ...
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0answers
135 views

Combine files in TopoJSON when one is simplified differently to the other

I have two .shp files, I am separately converting these to GeoJSON with ogr2ogr.exe and then combining the files with TopoJSON. Each file independently becomes a ~200kb topojson file, however the ...
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3answers
543 views

Simplifying Ways in OpenStreetMap Data

Is there a (current) best practice to simplify ways? I have found: https://github.com/podolsir/osmosis-simplifyways But besides not being alive, here (http://permalink.gmane.org/gmane.comp.gis....
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3answers
919 views

How to anonymise a gps file?

Imagine you have a GPS trace that you want to make anonymous, in the legal sense. How would you do this? Is snapping to the nearest x distance and stripping out the time enough? Are there ...
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2answers
188 views

Cannot Select 'Input line or polygon vector layer' when trying to simplify Shapefile

I'm trying to simplify a Shapefile by opening it in QGIS, Go to the Vector menu, selecting Geometry tools, and selecting Simplify Geometries... When I do this I get a modal window that I can fill out ...
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1answer
301 views

Is there a difference in results between Simplifying a geometry by different projections?

We have geometries in a PostGIS database projected in srid 4326. We need to have these geometries simplified with ST_SimplifyPreserveTopology. My question is whether this geometry needs to be ...
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2answers
12k views

Removing unnecessary vertices?

I have over sampled polygons that I need to simplify, without changing the shape. basically, I want to reduce the number of vertices, by eliminating the ones that are useless and have the polygons ...
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0answers
211 views

Query to merge simplified polygons according to the map scale-factor [closed]

I'm trying to construct a view in PostgreSQL that simplify polygons according to the map scale-factor. Basically I was reading this thread http://linfiniti.com/2011/06/scale-dependent-generalization-...
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0answers
53 views

QGIS - Simplification process creates a new polygon - how to avoid it?

I am trying to simplify a layer made of polygons. I have used different methods but the new simplified layer has a polygon which intersect with itself, thus creating a "new" polygon. Please see ...
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1answer
208 views

ArcGIS Raster To Multipoint Mac/OSX alternative

Is there an alternative to the ArcGIS Raster To Multipoint tool for Macs? The VIP thinning method is particularly of use. A comparative point cloud thinning/simplification tool to this would just as ...
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2answers
14k views

writeOGR with a spatialpolygon simplified by gSimplify

I'm using gSimplify (rgeos package) to simplify the geometries of a shapefile. The funcion works good, but now I can't write the output in a new shapefile. I tried some ways: writeOGR(simplyshape, ...
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1answer
335 views

How to fill a hole - with islands within?

In QGIS I have simplified a layer. At the end of the simplification process (using GRASS v.generalize), my final layer "lost" a polygon: see white space in image: How can I recreate a polygon which ...
2
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1answer
427 views

simplify tiled geometries while preserving anything on the edge

I have a dataset of polygons split into evenly sized tiles. How can I go about simplifying them, but not along the tile edges, so that there aren't any gaps between continuous features when the tiles ...
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1answer
215 views

Getting simplified UK boundary data?

I have some recent data that is at the Lower Super Output Area (LSOA) level for Greater Manchester. I wrongly assumed that the data was for the latest LSOA boundaries, i.e. for the 2011 boundaries. ...
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2answers
8k views

What is “Simplify tolerance” in QGIS's Simplify geometries tool?

I am trying to use QGIS 2.8 to simplify vector geometries. But I do not understand the significance of the Simplify tolerance value in the Simplify geometries tool. The documentation does not ...
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2answers
508 views

Complex Shapefile Compression Advice

I'm looking for some advice on how I can simplify this very detailed shapefile to ultimately be used for the web (as topojson) as a interactive heatmap. It was originally created from a raster file (...
4
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1answer
3k views

How Does Ogr2Ogr Simplify Work?

Can someone explain how the ogr2ogr simplify works? I am trying to use raster data which has a spectral resolution of 30m. The vector file that I am trying to import into Google Fusion is large in ...
3
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2answers
1k views

Collapsing multiple lines into single line?

I need to create a route (line) feature class from another feature class that contains multiple lines making up the same route. pic 1 shows the original feature class with the multiple lines. pic 2 ...
3
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1answer
410 views

Reducing number of points, keeping most recent data within given distance, using QGIS?

I have a HUGE dataset of points that were collected along a route. The data may change daily, and the most recent data is the most important. What I would like to do is take only 1 point from a given ...
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1answer
183 views

Simplifying polygons in ArcGIS considering contains-one-point topology rule?

I want to simplify polygons using the "Simplify Polygon (Cartography)" tool in ArcGIS 10.2. Additionaly there is one point in each polygon and this condition should still be fulfilled after ...
2
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1answer
622 views

Simplify a polygon dataset with a minimum distance between the new vertices

I would like to simplify a polygon shapefile where the resulting output has a minimum distance of 5 kilometres between the new vertices. We have ArcMap 10 on an ArcView license, FME and QGIS. I have ...
5
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1answer
546 views

Simplify a road network to obtain the intersections

In QGIS 2.6.1 in Ubuntu, I want to measure the density of block in this city (FYI my final aim is to measure the TOD level). I have the road network from French national IGN dataset BDTopo. I have ...
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0answers
143 views

How to simplify polygon shapefile and maintain topology? [duplicate]

I'm looking for a straightforward answer that actually works...not a 'duplicate question' flag. None of the other solutions posted in similar threads actually work...they all have dead-end answers and/...
2
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1answer
1k views

Why are my polygons automatically simplified/generalised when merging them in ArcMap 10.2?

I am creating a small land use map, as an exercise for visual image interpretation. I created a shapefile and started digitising polyogons with the polygon tool. The problem is that some of my ...
3
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1answer
1k views

Shapely's simplify won't simplify any more

I have a multipolygon in shapely, and I want to simplify it until it has less than a certain number of points. When I use the preseve_topology=False argument to geom.simplify, I can get the number of ...
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1answer
112 views

Generalize lines with specific points

It's been a while since I was here. I have this problem now. I have electricity line feature class and point feature class intersecting line features. What I need to do is simplify this line feature ...
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1answer
637 views

How can I find a Douglas-Peucker algorithm for simplification? [duplicate]

I want to understand simplification methods in GIS. I searched the Internet and found that the best simplification method is the Douglas-Peucker algorithm. I could not find any information about the ...
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0answers
49 views

Keep synchronization when simplify features from different data source

We have two shapefile data sources: 1 water-riverbank.shp With geometry type of Polygon which stands for the area of water 2water-riverline.shp. With geometry type of LineString which stands for ...
5
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1answer
1k views

ogr SimplifyPreserveTopology does not keep the Topology

I use ogr2ogr to simplify a layer of polyline, from the document: -simplify tolerance: (starting with GDAL 1.9.0) distance tolerance for simplification. This method will preserve topology, in ...