Questions tagged [generalization]

Process that simplifies the representation of geographical data to produce a map at a certain scale with a defined and readable legend. During the process, the information is globally simplified but stays readable and understandable.

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2
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0answers
328 views

Reducing the density of points based on zoom level

I have a Polyline like the one shown in the example, representing the path of a vehicle. GeoJSON markers show the vehicle's position over time. How can I reduce the density of the markers when the ...
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0answers
48 views

Optimizing identification of tree stand boundaries

I am working on a workflow to identify tree stand boundaries. My desired result is the blue lines - I know it will never be like that, but I need it to be as good as possible. My best result is the ...
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3answers
656 views

Automatically fill gaps and merge freshly generated polygons with the longest adjacent polygon

I get polylines automatically generated from AutoCAD from a colleague. Converting them into polygons with QGIS 3.6, I find out some sliver polygons and gaps in between, as shown in the picture below : ...
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1answer
48 views

How to generalize a country border using QGIS? [closed]

What are the steps for smoothening a country border using QGIS?
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5answers
2k views

Aggregating detached polygons using open source software

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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0answers
33 views

Does QGIS have Generalization toolset like ArcGIS Desktop?

In ArcGIS Desktop there are Generalization tools like: Merge Divided Roads Collapse Road Detail Resolve Road Conflicts Does QGIS have this toolset or is it possible to run these algorithms on QGIS?
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18 views

How to smooth interior polygons of one shapefile

I have a shapefile that includes the boundary of a field plus many interior polygons that represent levels of NDVI - we'll say High, Medium, and Low. The larger areas have jagged, irregular edges. ...
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0answers
24 views

Generalization with GRASS explodes number of polygons that are exported to GeoJSON

I have a shape file containing polygons with 10 geographical districts that together form a city, which I want to generalize without "sliver" artifacts and export to GeoJSON. When running this vector ...
3
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1answer
81 views

v.generalize does not affect some boundaries

All in all, I would describe myself as a QGIS (3.12.2) beginner and have now contact with GRASS (7.8.2) for the first time. I want to simplify the boundaries of my polygons considering the topology. ...
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1answer
35 views

Merging two different accurate polygon layers

I'd like to combine two layers of different administrative areas. One layer is more accurate (layer A) than the other one (layer B) in terms of generalization. So is there a prepared QGIS-tool to do ...
2
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3answers
976 views

Collapse dual lines to centerline doesn't exist in ArcGIS Pro?

I have ArcGIS Pro build 3308 (Ver. 1.1) and wish to collapse two parallel lines into one, however it appears that this function no longer exists - I have also tried using python for this and received ...
7
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1answer
126 views

Simplifying label geometry in QGIS

I have a bunch of linear data (trails) stored in PostGIS and visualized in QGIS for cartographic production. Many trails have switchbacks, and are generally very "weavy", which makes for difficult ...
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0answers
35 views

Problem when using Simplify Tool in QGIS

I want to simplify district borders. As I got bad results when using polygons I converted those polygons into lines but I still have the same problem that I get new vertexes or corners I don't want. ...
23
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5answers
2k 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 ...
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0answers
66 views

Mapshaper simplify equivalent in GRASS

I was shown the simplify function of https://mapshaper.org/, which removes unnecessary vertices in polygons. Now I'm looking for a similar function in QGIS and found GRASS generalisation. Since I'm ...
3
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1answer
241 views

Display multiple lines as one line in QGIS

I am working with the OSM Dataset and can´t find a way to display rails in a proper way. In a big scale the rails are displaying fine but as soon the lines begin to overlap in a smaller scale I don´t ...
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5answers
36k 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 "...
8
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3answers
4k views

QGIS equivalent to ArcGIS Aggregate Polygons?

I am looking for a tool in QGIS 2.40 that performs the function ArcGIS refers to as Aggregate Polygons. Basically it takes a group of polygons within a specified distance and creates a concave hull ...
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31 views

How to simplify and generalise global data for cartography?

I have a TIFF that shows biodiversity and I want to create a nicely looking cartography output. The data look like this If you can observe there are a lot of 'dots' and things can get a bit messy ...
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28 views

Clean up self-intersecting polylines in QGIS?

I have GPS data that contains self-intersections. This happens when someone walks around on "the same spot". Is there a way to clean up these in QGIS? I tried Smooth but that did not do the trick.
3
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3answers
84 views

Generalising lines of varying detail in QGIS

I am trying to generalise a line in QGIS so that I can export it as a vector without it having an unnecessarily huge file size. The line shows the GPS track of a road trip, and as such varies between ...
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 ...
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0answers
128 views

Generalizing railways from OpenStreetMap using ArcGIS Desktop?

I have dataset of railways from OpenStreetMap. It is really detailed. But i want to make generalization for map scale 1:500 000: remove small details of the railways and short branches. I`ve used ...
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0answers
127 views

Wang's Bend Simplify in QGIS

I am looking for an alternative to ESRI's Simplify Polygons - Bend Simplify method (I only have a Basic License). Is there an existing QGIS plugin which supports this specific polygon simplifying ...
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1answer
116 views

“Average” of two lines

I have a dataset of pairs of parallel linear features (railway tracks) and I need to simplify each pair into its central/median line. This could be achieved by computing a skeleton as suggested in ...
3
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0answers
132 views

Generalizing / simplifying multipolygon in PostGIS without missing polygons?

By following the rules from this site, I got the output but some polygons do not come within the simplified polygon. I think the problem is with topology. Is there any solution?
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0answers
95 views

Simplify a polyline/polygon using a threshold on maximum number of vertices in PostGIS?

The various simplification functions in PostGIS (e.g. ST_Simplify) uses a tolerance parameter for the maximum allowable deviation of the generalized shape from the original. My question is: Is there ...
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0answers
24 views

Conditional Expanding in ArcGIS Desktop?

I would like to reclassify a LC map given some conditional rules (raster with 8 classes total). Using the illustration, I would like to expand the green pixels (two distinct classes) on the white ...
1
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1answer
180 views

v.generalize in QGIS throwing “Unable to create table” error

I am trying to smoothen few polyline shapefiles using v.generalize in QGIS 3.4. But it's not working. Even i tried the same in QGIS 2.18. Getting the same error. Tried the same process in GRASS 7.4.2....
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0answers
50 views

How to remove complicated shapes in ArcGIS - generalization [duplicate]

What can be the way of simplifying polygons in ArcMap? I have a shapefile with buildings and I have to make them as simple as it's possible. I used already some tools, like: dissolve, union, ...
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0answers
63 views

Convex boundary of polygon [closed]

Is there any tool that can help me with my problem? I have polygons looking like this : And what I want, is to simplify or gain convex boundary of such polygons. I tried Simplify Polygon in ArcMap, ...
2
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2answers
325 views

Cartographic generalization: Dissolve “neighbour” / bordering polygon objects in QGIS

I have a polygon layer with buildings for the area of the whole city. My question is how to dissolve/aggregate/merge only those buildings, that are "neighbours", in a sense that they share at least ...
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1answer
149 views

Avoiding thin parts of polygons using ArcGIS Desktop?

I've used Simplify Polygon with 'Maximum Allowable Offset' 250m, and then Aggregate Polygons with 'Aggregation Distance' also 250m (opposite order also tested). Still I have thin parts of polygons as ...
5
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1answer
102 views

Getting WHERE statement to work in v.generalize?

I have a shape (its topology is terrible but I don't think it's the problem). I'm trying to simplify it to reduced it's size using v.generalise. I succeeded at reducing the whole shape but I ...
3
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1answer
53 views

Is there a built in way to reduce the amount of points in an IElement

I have a polyline element and I want to reduce the number of points (vertices?) that make up the line. I know it will make the curved sections jagged and that is fine. I just want to control (perhaps ...
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0answers
132 views

How to generalize shape with PyQGIS without much Distortion in the shape?

I was trying to generalize the the inner boundaries of the polygon. Looking for a PyQGIS solution for that any other possible python solution will be fine. I tried convex hull and simplify geometry ...
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0answers
28 views

Smooth Data Values Across Geographies with Zero Population

Looking to fill in gaps through generalizing a population count across U.S. counties. I.e., if a county has 0 population, but is surrounded by 5 non-zero counties, then change the 0-population county ...
1
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1answer
57 views

Remove small interstices on the edges of a polygone

How can I remove the white interstices on the edges (and interior) of a polygone or polyline, as represented in the first figure below? I want to get smooth and continuous edges, capturing the global ...
1
vote
1answer
929 views

Merging unconnected line segments using ArcGIS Desktop?

I am looking for a way to connect line segments that are unconnected. It is a shapefile for a network of rivers and all the lines are slightly disconnected. Is there something like aggregate ...
1
vote
1answer
150 views

How to generalize QGIS 3.0 Model so that I can install on multiple computers without setting up on every computer?

I am trying to create a model to work on multiple computers with little editing. I am working in QGIS 3.0. I am trying to get the model to first set the style for the layers based on a predefined qlr. ...
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0answers
737 views

Generalize Polygons in QGIS 3.0

I would like to use different generalization tools for polygons in QGIS 3.0. Especially for aggregation, simplifying and smoothing. Back using QGIS 2.8 there were the following possibilities: ...
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0answers
96 views

Speeding up workflow of generalizing OpenStreetMap road data?

Whenever I want to use OSM data for medium scale maps (e.g. 1:200.000) I run into problems. On the screenshot below one can see the orange street that goes from north to south. It has the attribut ...
42
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5answers
62k views

Smoothing/generalizing polygon in QGIS?

Is it possible to smooth or generalize a polygon in QGIS, perhaps by using a plugin like the generalizer-plugin for lines? I could convert my polygons to lines, smooth them and convert them back to ...
2
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0answers
278 views

Building footprint polygon simplification / generalisation

I'm looking for implementations of polygon simplification algorithms that preserve topology and overall rectilinearity. The input data is building footprints which often have squarish protrusions and ...
22
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3answers
14k views

Seeking Generalisation Strategies for Building Outlines in PostGIS?

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 ...
0
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1answer
54 views

Reducing filesize for landslide susceptibility map

I have a large .tif file that I would like to reduce to under 15MB (currently 650MB). The file shows 3 zones of landslide susceptibility (see pic below). I am processing it so that I can upload it to ...
1
vote
1answer
102 views

Options for generalizing raster?

I have a DTM raster which has too high a spatial resolution for my intended use, and I need it more generalized. Can't put my finger on how much more, but considerably more. My first thought was to ...
1
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1answer
222 views

Generalising Rasters using .ovr pyramid data?

I have to produce some lower spatial resolution rasters from a large number of very big geotiffs (c.800GB). It occured to me that since I've produced the pyramid overviews using GDAL already I could ...
25
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10answers
7k views

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. Do you know and use ...
2
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2answers
447 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 ...