gis | 易学教程

ST_HexagonGrid geom vector to find all points

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问题 I was reviewing this function in PostGis https://postgis.net/docs/manual-dev/ST_HexagonGrid.html 1) What I don't understand is what the underlying geom data would be. What's the source to get the USA map as shown? What is the DB schema? I think it could be one record, if I only need the USA boundary, not each state? 2) Is the result a list of points? or geom vectors? 3) If geom vectors, how do you convert them into points of lat and lng? 4) How to do approximate the hexigons to approximate a

How to ignore loading huge fields in django admin list_display?

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问题 I'm using django 1.9 and django.contrib.gis with an Area model that has a huge gis MultiPolygonField : # models.py from django.contrib.gis.db import models as gis_models class Area(gis_models.Model): area_color = gis_models.IntegerField() mpoly = gis_models.MultiPolygonField(srid=4326) class Meta: verbose_name = 'Area' verbose_name_plural = 'Areas' I have the associated AreaAdmin class to manage the Area s inside django admin: # admin.py from django.contrib.gis import admin as gis_admin class

GIS基础知识——厂商介绍（三）Intergraph公司

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INTERGRAPH(鹰图)公司创建于1969年，公司总部设在美国阿拉巴马州汉茨维尔市，是世界上最大的交互式计算机图形系统公司，在世界上60多个国家和地区设有分支机构，员工近五千人，年营业额6亿美元。在公共设施管理工业已有超过30年的工程经验，是全球AM/FM/GIS领域市场占有率最高的公司。鹰图公共安全公司（INTERGRAPH PUBLIC SAFETY，简称IPS）是隶属于INTERGRAPH公司的全资子公司，它致力于公用事业、通信及公安消防等领域的应用研究，并已成为这些领域的世界领导者。在公用事业领域，IPS作为一个拥有超过30年历史的行业领导者、技术革新者，为电力、电信、有线电视、管线、煤气及自来水公司提供了一系列功能强大的产品和完善的服务。我们的基于GIS的自动制图与设施管理(AM/FM/GIS) 及空间资源管理（GRM）的解决方案为这些企业提供了无缝的工作流--将企业的空间设备管理、工作管理、劳动力及运行管理有机地集成为一个整体。在通信领域，作为网络资源管理空间操作支持系统(G/OSS)的提供商，IPS为国际通信市场开发了基于Microsoft作业平台的地理空间操作支持系统。本解决方案包含了一系列已被世界上一些大的通信公司成功证明并应用了的软件、硬件和服务产品。IPS将始终以满足下一代通信公司的全方位需求为目标。在公共安全领域方面，IPS作为行业市场的领导者

Fastest way to extract a raster in R (improve the time of my reproducible code)

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问题 I'm wondering if I have maximized the speed at which a mean of an area buffered around a point in a raster can be extracted. Can performance be improved any further on these LOCALLY? I use parallel mclapply already, and I know I could get further gains by setting up and running this on a cluster (use a cluster or get more cpu's is not the answer I'm looking for). Replicate some data: library(raster) library(parallel) library(truncnorm) library(gdalUtils) library(velox) library(sf) ras <-

Contours around scipy labeled regions in a 2D grid

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问题 I'm trying to find the bounding polygons of all of the wholes in a 2D grid with a large no-data value (1e6). I've got the listing of holes working using scipy's label. Without dipping into gdal's polygonalize, is there an easy way to generate the bounding polygons? I see that there is matplotlib.pylab.contour, but this tries to draw a plot, which I really don't want. Any recommendation on how to get bounding polygons for each label (preferably with a way to simplify the polygons a little if

Contours around scipy labeled regions in a 2D grid

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Mysql function MBRContains is not accurate

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问题 I have the following POLYGON (in the image you can see the area it covers) POLYGON((-74.05100448502202 4.7239278424321,-74.05092938316898 4.7241416902206,-74.04830618275201 4.7237460717602,-74.04643668306903 4.7234306460692,-74.04635688735101 4.7234105978214,-74.04636526925401 4.7233310730989,-74.046191260944 4.72327293317,-74.04579027069599 4.7232007594583,-74.04141290558402 4.7214258184083,-74.03746201170497 4.7197791822891,-74.03565688503801 4.7189879401666,-74.033484295736 4.7180897723398

arcgis for javascript之ArcGISDynamicMapServiceLayer图层控制的实现

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图层控制是非常多GIS系统里面必须的一个小功能，本文就说说arcgis for javascript下ArcGISDynamicMapServiceLayer图层控制的实现方式。首先看图：实现效果重点有下面两点：1、获取ArcGISDynamicMapServiceLayer的图层；2、控制图层的显示。图层的获取可通过layerInfos实现，图层的显示通过setVisibleLayers实现，源码例如以下： <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no"/> <title>Simple Map</title> <link rel="stylesheet" href="http://localhost/arcgis_js_api/library/3.9/3.9/js/esri/css/esri.css"> <style type="text/css"> @import "http://localhost/arcgis_js_api/library/3.9/3.9/js

ArcGIS Javascript 异常之No 'Access-Control-Allow-Origin' header

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本文只描述现象与处理措施，不讨论原理。开发过程中遇到此异常，查询后网上说是跨域访问的问题，给出的解决方案是通过JQuery的跨域访问机制来解决，难道我需要直接找ArcGISTiledMapServiceLayer相关代码，去重构吗？还有给出的解决方案如下，http://resources.arcgis.com/en/help/rest/apiref/config.html，大意就是要设置一下ArcGIS Server服务，可服务是别人的，设置不了。代码如下，在地图类型切换时需要调用另一个网址，就报出了如下错误。 if (tp == "mp") { //移除之前 map.removeLayer(basemap); //地图 basemap = new ArcGISTiledMapServiceLayer("http://xxx.xxx.xxx.xxx.xxx.xxx"); $("#mptype").val("mp"); map.addLayer(basemap); } 实际上两个图层域名是差不多的，不知道为什么出现这个问题。后来尝试了下，在地图初始化的时候就实例化两个ArcGISTiledMapServiceLayer，在地图切换的时候进行图层的添加、删除，不进行实例化，即解决问题。大致代码如下： function loadMap(lnt,lat,zo0o) { zoom

ArcGIS 添加 MarkerSymbol 弹出“图形符号无法序列化为 JSON”错误

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　　今天在做一个demo，向自定义图层中添加MarkerSymbol的时候，弹出“图形符号无法序列化为 JSON”错误，之前都没有出现过这个问题，我们首先来看一看我是怎样去添加图层，然后向图层中添加Graphic的，这个比较简单，直接贴出相关代码。　　　　　　 GraphicsLayer carLayer = new GraphicsLayer(); carLayer.ID = "CarLayer"; carLayer.Renderer = new SimpleRenderer() { Symbol = this.Resources["Medium"] as ESRI.ArcGIS.Client.Symbols.MarkerSymbol }; Graphic carGraphic = new Graphic(); carGraphic.Geometry = new ESRI.ArcGIS.Client.Geometry.MapPoint(Convert.ToDouble("12697297.9815139"), Convert.ToDouble("2577264.46557406"), new ESRI.ArcGIS.Client.Geometry.SpatialReference(102100)); carLayer.Graphics.Add(carGraphic);

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