polygon

问题 I have a MySQL database that contains geo-tagged objects. The objects are tagged by using a bounding polygon that the user draws and my program exports into the database. The bounding polygon is stored in the database as a Polygon (the MySQL spatial extensions kind). I can think of a couple ways to do this, but I'm not very pleased with any of them, as this needs to be an efficient process that will execute fairly often, although on probably only < 50,000 records in the pertinent table. I

问题 In Software like ArcMap one can create centroids for polygons within a polygon. In cases like the one shown below this is necessary. In R it is possible to calculate centroids of spatial polygons with rgeos::gCentroid() . However there is no way to force the calculation of centroids within the polygon. library(rgdal) library(rgeos) x <- readWKT("POLYGON ((1441727.5096940901130438 6550163.0046194596216083, 1150685.2609429201111197 6669225.7427449300885201, 975398.4520359700545669 6603079

问题 In Software like ArcMap one can create centroids for polygons within a polygon. In cases like the one shown below this is necessary. In R it is possible to calculate centroids of spatial polygons with rgeos::gCentroid() . However there is no way to force the calculation of centroids within the polygon. library(rgdal) library(rgeos) x <- readWKT("POLYGON ((1441727.5096940901130438 6550163.0046194596216083, 1150685.2609429201111197 6669225.7427449300885201, 975398.4520359700545669 6603079

问题 My current implementation doesn't show anything on the form even though the collections I thought bounded have data (I checked in debug). Here's some code: public event PropertyChangedEventHandler PropertyChanged; PointCollection imagePoints; public PointCollection ImagePoints { get { return this.imagePoints; } set { if (this.imagePoints != value) { this.imagePoints = value; if (this.PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs("ImagePoints")); } } } } and the

问题 I have looked around to find an example of how to take a polyline and create a buffer around it so I end up with a polygon. So far I found out I need Minkowskis Sums to do so, but I can't get my head around to raw algorithm and translate that in to code. I would prefer an example in C# or a walkthrough of the algorithm. 回答1: You could use the OffsetPolygons() function in the Clipper library, but first you'd need to convert the polyline into a polygon. Do this by appending to the polyline a

问题 Ruby noob here. Trying to display a list of points as a polygon on a google map using the gmaps4rails gem (awesome gem by the way). Any suggestions based on code sample below would be much appreciated! I can see the outline for the map, but no map and no polygon. Update: this code has been updated and the problem is solved. Class Schoolpoint is a list of lat/long pairs that belong to School In my controller: @polyjson = [] schoolpoints = [] Schoolpoint.where(:school_id => params[:id]).each do

问题 Ruby noob here. Trying to display a list of points as a polygon on a google map using the gmaps4rails gem (awesome gem by the way). Any suggestions based on code sample below would be much appreciated! I can see the outline for the map, but no map and no polygon. Update: this code has been updated and the problem is solved. Class Schoolpoint is a list of lat/long pairs that belong to School In my controller: @polyjson = [] schoolpoints = [] Schoolpoint.where(:school_id => params[:id]).each do

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 2 years ago . In order to create a VBO in OpenGl, I need to convert polygons to triangles. Is there an example of script/code somewhere that would describe this ? I would need something robust for convex and concave polygons. 回答1: Ear clipping is by far the best way to do this. It is fully robust for both convex and concave

问题 In three.js there is a function triangulateShape() . Now I encountered a failure to triangulate polygons that are simplified using Javascript Clipper. Simplifying in Clipper is done using Unioning. Wikipedia article determines unioning as finding the simple polygon or polygons containing the area inside either of two simple polygons. The same article says that in simple polygon "exactly two edges meet at each vertex" and also determines a weakly simple polygon, where edges can meet, but says

问题 I would like to display the polygon of Canada on a leaflet map. # create map library(leaflet) m = leaflet() %>% addTiles() m I was able to find the polygon for Canada: http://www.gadm.org/country. I chose the SpatialPolygonsDataFrame format for R, but there are other formats available (such as Shapefile) # load object in R load("country_polygons/CAN_adm0.RData") pol_can <- gadm How can I display the shape on the map? I assume I have to leverage the sp package but I could not figure out how to