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百度 旅游就是逛街其余时间上课洗脑提起公司组织的旅游，吴女士马上说：那根本不是什么旅游，每到一个城市就是逛街，逛完街大部分时间都是上课开会。
Topology describes non-metric relationships among geometric figures, such as adjacency, containment, and orientation. It is a branch of Mathematics, which deals in geometry without measurement.
584 questions
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Slight overlap after clipping polygon layer → sliver polygons appear when using Difference
I'm working with two polygon layers, each containing multiple features. I'm clipping one layer (Layer A) using another (Layer B), expecting the result to be entirely within Layer B.
However, when I ...
- 83
3
votes
2
answers
385
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Algorithm to find "streambeds"
I'm interested to know if there is a term for what I'm looking for, and then if there are well-known algorithms to find it, or even existing implementations.
For an arbitrary topography (assume I have ...
- 181
3
votes
1
answer
128
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Extracting common boundary between adjacent polygons using Python
I have a shapefile containing two features, each representing a different crop type geometry. After conducting raster analysis using satellite imagery, I have delineated the boundaries of these crop ...
- 942
2
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29
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Do QGIS geoprocessing tools honour snapping rules/tolerances?
Do QGIS geoprocessing tools honour snapping rules/tolerances?
Additionally, do the Advanced Digitizing tools, recognise snapping rules? Specifically the 'Merge Selected Features' tool.
Another way of ...
- 3,820
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41
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Vector smoothing (polygons): topology/geometry problems
I performed a raster segmentation from a Spot6 satellite image with OTB. I polygonized/vectorized this raster segmentation in order to get a vector file. To limit the pixelation of this cover, I was ...
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53
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Polygon simplification [closed]
How do I simplify complex polygons in order to get simpler detailed polygons like this :
... keeping their topology
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22
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Using v.overlay in GRASS when boundaries aren't exactly identical
I use v.overlay with a processed map of subbasins and a product of r.water.outlet built by gage coordinates. However r.water.outlet produces a basin very close to subwatersheds (that were built by r....
0
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43
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Error id 137 occurs while validationg topology in Arc Catalog
I'm trying to build and validate a topology to ensure that the relations between features of Contours shapefile is correct.
I have created a new Personal Geodatabase named topology and then a Feature ...
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2
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106
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Merging parallel segments of lines into one line
I would like to prepare a generalization of the railway network extracted from OSM. The generalization should preserve the topology of the network and merge all parallel lines into one.
For example:
...
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0
votes
1
answer
58
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Combine rasters based on touching/overlapping areas in QGIS
I have two raster layers made up of 0/1 pixels. They are both derived from a slope layer, one
(A) where the slope is greater than 60 degrees, and
(B) where the slope is greater than 50 degrees
So A ...
- 6,226
3
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1
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132
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Removing loops from line features in QGIS
I have written some PyQGIS code to generate cliffs from a DEM automatically. The general process:
starts with a raster of slopes > 60°
tries to fine-tune those areas using a variety of raster-...
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1
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1
answer
94
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Highlighting upstream and downstream connected lines
I have a shapefile of a water supply network and need assistance with a method to achieve the following in Qgis: When I select a line, I want to highlight all the connected downstream and upstream ...
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61
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Snapping in PostGIS topologies
I'm trying to create a topology from a geographic table in PostGIS with the boundaries of adjacent polygons snapped to each other. I prepared the topology with the following commands:
SELECT topology....
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0
votes
1
answer
198
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Fill polygon with circles
Essentially, I need these polygons to be circle packed with a varying degree of circles, using the red ones as an example.
The green polygons are represented as a canopy layer for a topology report. ...
- 157
0
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44
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Extract a hierarchical topology from stream network
A typical stream network has a hierarchical topology that resembles a cladogram (phylogenetic tree). There are many software tools that have been developed to analyze variables along a cladogram, ...
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