Generalisation is the simplification operation applied on spatial data when their representation scale decreases.

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22 views

v.generalize on massive vector data

I have a contour line file that covers the most part of north italy (shape is 0,6 gb) and I want to use v.generalize (snakes algorithm) on it. Because of the large file size, if I use Grass 6.4.3 I ...
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1answer
45 views

How to simplify a multiline geometry in QGIS?

I'm trying to simplify my shapefile, which uses a lot of vertices to represent curvatures, by using the Generalizer plugin. But no matter what threshold I use for Douglas algorithm, it still includes ...
1
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1answer
48 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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2answers
46 views

how to get a low level road network from openstreetmap data?

I've extracted the road network of a city from openstreetmaps (filetype: osm). One part of the road networks look like this: However, there are too many details in this data. I'd like to represent ...
6
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1answer
92 views

Competing approaches to line & polygon simplification

There seems to be a few theoretical options around at the moment for geometric simplification. Douglas–Peucker seems the most established, followed by Visvalingam's approach (used by d3.js). Now ...
4
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1answer
138 views

How to maintain right-angles when buffering?

When buffering some polygons I am trying to avoid the curved buffered area like this: I'm trying to do thins within an FME workbench but if someone knows how its done in other software that would ...
7
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4answers
495 views

How to generalize a point feature class

I have a point featureclass with a point for every 25cm - in Total 400,000 Points. I would like to reduce this resolution to one point every Meter. How could I instruct ArcGIS Advanced(ArcInfo) to do ...
2
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0answers
80 views

Is there a way to build topology and work with topology relations in PyQGIS?

Is there a way to build topology and work with topology relations in PyQGIS? I'm asking because I need to run some custom generalization algorithms on my data, and I need to preserve topology. ...
2
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2answers
133 views

Merge point features within a given radius [duplicate]

I have a file in QGIS with 5000 points. Some of the points are really close to each other (5m). How can I cluster the point features to one point feature if they are within 5m? The new points should ...
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0answers
57 views

How to generalize road network to be exact angle to each other?

I need to generalize a road network to be an exact angle to each other, we are talking about parallel streets like New York. The thing is that when you generalize, you do it per feature. I am trying ...
3
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1answer
170 views

Flatten GIS data to a schematic

I want to take a network of roads and lanes and reduce them to a schematic that shows their relationships but not their geographic shape. A similar concept has been used for the London Underground ...
6
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6answers
449 views

Tool/Algorithm for generalizing OSM-Files for printing maps

Is there a tool or algorithm to (topological) generalizes OSM-shapes? I would like to build a printable map in different scales. In the image below you can see the same divided road (yellow) at ...
2
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1answer
68 views

How to smooth a raster in a rectangular fashion using gaussian blur?

How do I adjust the code for the Gaussian Blur posted in the thread: What raster smoothing/generalization tools are available? to retain the resolution/gradients in the y direction and blur only ...
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0answers
133 views

When digitizing Lines, vertices are automatically generalized when finished feature

I am creating lines(feature class) and when the feature is finished Arcmap 10 will automatically generalize/smoothens the line. Is there any reason why this is happening? is this a bug of ArcMap 10? ...
2
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1answer
137 views

filter / generalize elevation points on the basis of some conditions

I wanted to generalize many elevation points in a rectangular area (about 700 square km). I need to take about 3 points for square km. These points must satisfy some conditions: One of these ...
5
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2answers
825 views

Tips for minimizing shapefile size without compromising geographical detail?

I work for a state government's fisheries service, and lately we've been digitizing a lot of our regulatory boundaries within the state's waters that we'd like to service out on web maps. ...
6
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1answer
219 views

Raster aggregation in ArcGIS

I'd like to aggregate a raster from 1m to 6m in ArcGIS with a custom rule. For example, each cell value of aggregated raster = mean value of 5 highest cell values from 36 aggregated values. How do I ...
7
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2answers
322 views

Using ArcGIS to filter cells where 7 or 8 of the neighbors are different

I have land cover data that I would like to clean using some generalization tools. Majority filter does almost exactly what I want, but is missing one key option. Majority filter allows you to change ...
4
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0answers
139 views

GeoServer pregeneralized layers not working as expected

I've set up GeoServer 2.1.4 and installed the feature-pregeneralized-2.1.4.jar plug in and processed my shape files into each of their separate folders with the generalized shapefiles and I've check ...
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2answers
878 views

How to generalize SpatialPolygons and conserving topology in R?

I would like to generalize a SpatialPolygonsDataFrame in R to make plotting more efficient. The polygons I have result in huge pdf plots that are slow to load and hard to integrate into a document. ...
6
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1answer
125 views

Finding Ring Smaller than a certain tolerance

In Simplifying a shapefile for world timezones http://efele.net/maps/tz/world/ all generalize/simplify algorithms fail on 5 countries/states, shown in this shape file ...
6
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3answers
4k views

How to smooth/generalize a polygon in qgis

Is it possible to smooth or generalize a polygon in qgis? Ìs there a plugin available like the generalizer-plugin for lines? I could convert my polygons to lines, smooth them and convert them back to ...
6
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2answers
1k views

Raster generalization - buffers in rasters, expand pixels?

Is it possible to create buffers for pixels of raster files? Actually I need to expand the pixels classified as 1 (in white in the figure) with a spatial range of 1 or 2 pixels, in order to perform ...
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4answers
876 views

How to aggregate detached polygons?

Is there any open-source library to aggregate detached polygons? I know that there is a tool in ArcInfo, but it is commercial.
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1answer
933 views

Changing the scale (generalisation) in ArcGIS 10

I have 2 polygon layers, accordingly 1:10 000 and 1:500 000. I want to generalize the first layer from 1:10 000 to 1:500 000. I tried using Simplify polygon tool, and since these scales relate to ...
2
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1answer
676 views

Why does aggregate polygons consistently error out?

I'm using aggregate polygons on a dataset with three large study areas. It did not work. So I split it into separate areas and did it again. Two of the three areas (which were smaller than the third) ...
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2answers
242 views

Need an explanation on a network simplification algorithm

I try to implement the algorithm described in this paper (page 8), but there's a place that I can't understand, and the authors do not provide a more detailed explanation or pseudocode. They show how ...
3
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1answer
261 views

Is it possible to simplify orthogonal polygons with OpenCarto Java Library?

I want to know if simplification of orthogonal polygons can be done with OpenCarto Java Library. If yes, does it have any API documentation? Cheers, Sanjeewa
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1answer
469 views

Why does GRASS eliminate polygons when using v.generalize?

I am facing a dilemma while trying to use v.generalize to simplify polygons which are similar in size and structure to US Counties or States. Often, I lose polygons from the data set after running ...
13
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3answers
1k views

Best practices for visualising clustered features in web maps?

I'm looking for the best symbol to display clustered features in the ArcGIS Server JS API. I don't like the "fly-out" animated cluster symbol, as used in the Silverlight API clustering or the JS ...
11
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4answers
415 views

How to generalize coastlines?

I have a large set of data points that essentially represent the coastline of the world. I don't know the exact resolution but I'd say it's in the neighbourhood of 5-10m. Imagine a set of points ...
8
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3answers
166 views

Location storage and query algorithms. How do they work?

One of the most important aspects of a GIS-equipped database is that it provides the user with the capability to quickly query for all points within some arbitrary geographic area that match some ...
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4answers
7k views

What raster smoothing/generalization tools are available?

I have a DEM that I would like to smooth or generalize to remove topographic extremes (chop off peaks and fill-in valleys). Ideally, I would also like to have control over the radius or level of ...
6
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1answer
95 views

Dividing the world space to geographic sub-space

I am trying to divide the world space to geographic sub-space from "general" to "specific" locations and without using latitude and longitude information. That is, I am trying to think about the world ...
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2answers
801 views

Using “Merge Divided Roads” tool with lesser parallel lines

When using the "Merge Divided Roads" tool, it merges roads that "trend generally parallel to one another". This means that from figure one.. It will merge the beginning, where the roads are close to ...
4
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2answers
1k views

Tracklogs to single line OR several lines to one line?

Setting: I have several trucks driving out of my factory delivering goods and coming back for more deliveries. These trucks are equipped with GPS so that they may return tracklogs to me. These ...
4
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4answers
292 views

Enlarge/roughen the Vector Size of Tiles

Im currently running a GeoServer and my task is to make the vectors rougher thant they are right now. I really dont know where and how the Geoserver processes the data from the DB and how it will be ...
6
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3answers
784 views

Retrieve polygon smallest MBR

I have a postgis table containing polygons. I want to transform my polygons to 4 points polygons : retrieve the smallest MBR. Here comes an illustration of what I want : My original polygon is ...
18
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4answers
2k views

Generalisation Strategies for Building Outlines

I have a dataset of building footprints vectorised from a raster dataset. The dataset is currently just a vector representation of the raster data. I would like a polygon dataset that only has ...
8
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2answers
1k views

How do I combine high resolution and generalized hillshade rasters to produce enhanced shaded relief?

I often add LiDAR data to a map along with a shaded relief. Most of the time i have to generalize the LiDAR dem depending on the scale of the map. Still, there is often too much detail and mountain ...
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5answers
2k views

Rendering overlapping lines

I am making a map containing information about public transportation: busses, trams, etc. The map will have a layer containing for example the tram lines. Each line has its own colour, and is ...
23
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10answers
3k views

What are the existing solutions to automate generalisation/simplification of geographical data?

I am looking for existing solutions (softwares, libraries, methods, etc.) to automate the generalisation/simplification of geographical data as presented there, and also there. How do you proceed ...
20
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5answers
1k views

Simplifying geometries (generalization)

What are the recommended ways of simplifying geometries? Keeping in mind projections, and simplifying state geometries for example. I've heard about converting to an 'equi-distant' projection that ...