point-in-polygon

问题 This is a bit tricky question for you computer scientists. Let's say that I have a two dimensional array/matrix of 100 by 100 entries, arr[i][j]. Where i and j goes from 0-99. This can be envisioned as a square of dots with each dot corresponding to a data value. Now, If I define a 4 point polygon and know the indicies of the 4 points: Is it possible (is there an clever algorithm) to loop through only those entries in the matrix that lies inside of the 4-point polygon? That is, every value of

问题 In my react application , I've drawn a polygon by using some points and then I'm trying to find out if mouse current location is inside the polygon or not. I'm using d3.polygonContains and passing it points array with current location points but it always returns false , although points are inside polygon. here is an example; let points = [ [ 42.34624, -71.06024 ], [ 42.33558, -71.06616 ], [ 42.32632, -71.05835 ], [ 42.32987, -71.05428 ], [ 42.34732, -71.05432 ], [ 42.34618, -71.05973 ], [ 42

问题 I am using a point-in-polygon check in php, but I am getting major errors - as in points that are not in the polygon are coming up as inside. My basic functions are typed out below (found here, modified from a class to a simple function: http://www.assemblysys.com/dataServices/php_pointinpolygon.php). The only thing I can think of is some kind of rounding errors someplace? As one example, I am trying to determine whether a point is in Central Park, a simple square, but I get positives from

问题 i have a typical question with the Geometric datatype of mysql, polygon. I have the polygon data, in the form of an array of latitudes and longitudes, ex: [["x":37.628134, "y":-77.458334], ["x":37.629867, "y":-77.449021], ["x":37.62324, "y":-77.445416], ["x":37.622424, "y":-77.457819]] And i have a point (Vertex) with coordinates of latitude and longitude, ex: $location = new vertex($_GET["longitude"], $_GET["latitude"]); Now i want to find whether this vertex (point) is inside the polygon.

问题 I'm trying to figure out how best to do this, I have a map with one Polygon drawn on it. Since it doesn't seem as though the Google Maps API V2 has a touch detection on a Polygon. I was wonder if it is possible to detect whether the touch point is inside the Polygon? If so then how, my main goal is to outline a state on a map and when the user taps that state it will show more details inside a custom view. As of now I am able to capture the MapOnClick of the map but when the user taps inside

问题 I'm trying to figure out how best to do this, I have a map with one Polygon drawn on it. Since it doesn't seem as though the Google Maps API V2 has a touch detection on a Polygon. I was wonder if it is possible to detect whether the touch point is inside the Polygon? If so then how, my main goal is to outline a state on a map and when the user taps that state it will show more details inside a custom view. As of now I am able to capture the MapOnClick of the map but when the user taps inside

问题 I tried using the following code for the Even-Odd Rule from Wikipedia # x, y -- x and y coordinates of point # poly -- a list of tuples [(x, y), (x, y), ...] def isPointInPath(x, y, poly): num = len(poly) i = 0 j = num - 1 c = False for i in range(num): if ((poly[i][1] > y) != (poly[j][1] > y)) and \ (x < (poly[j][0] - poly[i][0]) * (y - poly[i][1]) / (poly[j][1] - poly[i][1]) + poly[i][0]): c = not c j = i return c Unfortuantely, it's giving wrong results for my simple rectilinear polygon

问题 Assume I have a data file called zone with 1994 strings of 2D coordinators denoting coordinates of vertices of polygons like the following (the very first number on the RHS of each line denotes the zone ) c1 <- "1", "1 21, 31 50, 45 65, 75 80" c2 <- "2", "3 20, 5 15, 2 26, 70 -85, 40 50, 60 80" ..... c1993 <- "1993", "3 2, 2 -5, 0 60, 7 -58, -12 23, 56 611, 85 152" c1994 <- "1994", "30 200, 50 -15, 20 260, 700 -850, -1 2, 5 6, 8 15" Now I want to manipulate these strings in such a way that

问题 Is there some library for node.js or javascript in general that provides a function to check if a coordinate is in a geojson multipolygon? I'm trying to create a small HTTP API that tells me which multipolygons (representing countries, counties, cities, etc.) contain a given coordinate. I thought that I'll hold a list of all multipolygons & their bounding-box in memory and then first check for each polygon if its bounding box cointains the coordinate. If yes, then it'll check if the

问题 I have a table containing point CREATE TABLE Points { pointID BIGSERIAL PRIMARY KEY NOT NULL, thePoint GEOGRAPHY(POINT) } CREATE TABLE Polygons { polygonID BIGSERIAL PRIMARY KEY NOT NULL, aPolygon GEOGRAPHY(POLYGON) NOT NULL, } I wish to find all the points that are contained in each polygon. i.e the result should look like polygonID| pointID ------------------- 1 | 1 1 | 2 1 | 5 1 | 7 2 | 2 2 | 3 ... I managed to go point by point and to figure out if it's in the polygon using ST_CoveredBy