Linked Questions
14 questions linked to/from Calculating maximum distance within polygon in x-direction (east-west direction) in PostGIS?
21
votes
4
answers
19k
views
Calculating roundness/compactness of polygon?
I am trying to find ways to quantitatively describe the shapes of various polygons. For my project, these polygons represent lakes, rivers, lagoons, and parks. So they can be almost any shape. One ...
- 371
16
votes
4
answers
6k
views
Getting max length of polygon and average width using PostGIS [closed]
I have in PostGIS a polygon type table.
I need to calculate automatically the maximum length of the polygon:
And the second one is the average width:
I am doubting if this is possible as, although ...
- 3,738
10
votes
1
answer
5k
views
How to create linestrings with a definite angle and length, that are fixed to a point
I want to create linestrings with a definite angle (e.g. 160°) and length (e.g. 2m) that are fixed to a number of points of another linestring. So, I want to use the ST_DumpPoints function to find the ...
- 4,414
8
votes
3
answers
3k
views
Antipodal distance (or polygon fetch or polygon diameter) for concave polygons
I am working on some class examples in Python implemented within ArcMap to calculate the antipodal distance within a polygon. This is fairly routine for convex polygons, however, for concave polygons,...
user681
4
votes
3
answers
1k
views
Selecting polygons with a minimum internal straight line value - ArcGIS 10
I have a map of polygons representing forest stands. I am trying to sort through them to find those polygons that have a minimum internal distance of 200 m in a straight line (my field sampling will ...
- 339
2
votes
1
answer
4k
views
Finding longest line segment within polygon? [closed]
I have been looking around to find a way to calculate the longest line within a polygon.
Determining longest line segment within polygon that passes through its centroid? and Calculating maximum ...
- 375
3
votes
1
answer
2k
views
Calculate max polygon length & width using mean aspect
I have a shapefile of polygons, and wish to calculate the maximum length (parallel to flow) and width (perpendicular to flow) - both straight lines. I calculated the mean aspect (i.e. flow direction) ...
- 271
4
votes
2
answers
2k
views
How to align edges of overlapping polygons in the middle line?
The problem
Here are two polygons that overlap.
My ultimate goal is to reshape the grassland (green poly) and the reservoir (blue poly) so they share the edge somewhere in the middle of their ...
- 29.9k
4
votes
1
answer
945
views
How to find the distance from a point to a polygon, via another point, in R
I am trying to calculate the distances between a central point, and the edge of a polygon, along straight lines drawn between the central point and another set of points (where necessary extended ...
- 193
1
vote
1
answer
718
views
Calculating field length in certain directions (raster)?
Currently I'm working on winderosion. For my purpose I like to calculate the length of agricultural fields in certain wind direction. I would like to do it for raster.
To be more precise, I have ...
- 140
5
votes
1
answer
332
views
Spatial graphing, distribution of polygon area over latitudes
Given a polygon in a PostGIS database, what is the best way to create a graph of its distribution over a range of latitudes? I'm picturing a graph of a curve, where the proportion of the total area ...
- 1,661
2
votes
0
answers
919
views
Is there an R package for finding the maximum-area rectangle in a non-convex polygon?
Does anyone know if there is an R package out there with an algorithm which finds the largest rectangle within non-convex polygons? I have Googled, searched the R Sig Geo archives, and looked here on ...
- 396
1
vote
0
answers
296
views
How to get intersected points between polygon and line in desired order
I have polygon for example "POLYGON((5 1, 6 1, 6 5, 5 5, 5 1))" that I want to intersect with line "LINESTRING(0 2, 10 2, 10 3, 0 3, 0 4, 10 4)" and get intersection points in the order that they ...
- 250
1
vote
1
answer
73
views
Total area of polygons over latitudes
I'd like to calculate the total area of several polygons along a north-south axis. A bit like this http://www.closr.it/canvas/1307/#/spot
There is a similar question with R :
Spatial graphing, ...
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