2) On April 22, 2014, the algorithm verification of cell-level triangulation network was completed. The verification results are as follows:
Purpose: To verify whether the Thiessen polygon calculated by the cell offset algorithm and then using the Thiessen polygon plugin is correct.
Verification process:
1. Use 20m azimuth offset to generate cell-level offset latitude and longitude. 3935 outdoor sites were verified, and 3598 outdoor sites generated Thiessen polygons normally.
2. Use the 10-meter azimuth offset to generate the cell-level offset latitude and longitude, and use the plug-in tool to run for 30 minutes without getting the result.
3. Carry out case analysis on outdoor sites where Thiessen polygons are not normally generated in step 1.
4. Through case analysis, it was found that most of the polygonal outdoor stations were not generated normally because the longitude and latitude errors maintained by the prefecture and city caused many stations to be too close. Using the latest data corrected by the prefecture and city, it was recalculated to find 4050 outdoor stations, of which 4039 were generated normally.
Verification conclusion: Cell-level Thiessen polygons can be normally generated by using the 20-meter azimuth offset method.
3) Component optimization algorithm: The calculation process can be optimized by sorting according to latitude and longitude.
5) If the development encounters a bottleneck, consider coordinate conversion: the
projection parameter settings are as shown in the screenshot, both places can be used, in fact, the same projection parameter is called.
The data and methods you have exported are correct. As for the principle, it is difficult to explain clearly. The data is in the conversion of two different coordinate systems. The WGS84 latitude and longitude coordinate system is a geographic coordinate system (spherical coordinate system or geocentric coordinate system), UTM (Universal Transverse Mercator Projection) is a projected coordinate system, also known as a plane coordinate system. There is a corresponding mathematical method to convert the conversion, and the commonly used GIS software on the market can convert it. The mathematical models and parameters of the two coordinate systems are public information and can be queried online.
Regarding the resolution of satellite images, I checked the area of Hubei Province, which is about 185,900 square kilometers (Baidu data, we have the exact administrative area, but it's not much different), and the resolution of 0.6 meters (U.S. Quickbird satellite) The market price of satellite films is around 200 yuan per square kilometer, so the cost of high-definition images in the province is still relatively high. The distribution of Google high-definition images is basically prefecture-level cities or hotspots, and will not cover the whole province. Suburbs are generally 2.5-meter resolution images, but there will be a small amount of distortion when intercepted. The original 2.5-meter satellites are representative of the domestic resource 3 satellite, French SPOT satellite, Japan ALOS (lost connection after April 2011) Wait.
6) We can directly change it to 20 in the state of projected coordinate meters, and then we have calculated 0.00000925 degrees = 1 meter in the state of longitude and latitude, so the value of 20 meters corresponds to 0.000185. But there are differences in different regions. This value is close to the position of the equator.
7) https://github.com/Hoten/Java-Delaunay
Oh, he hit the Stanford University intranet
Java implementation by Connor Clark ( www.hotengames.com). Pretty much a 1:1 * translation of a wonderful map generating algorthim by Amit Patel of Red Blob Games, * which can be found here ( http://www-cs-students.stanford.edu/~amitp/game-programming/polygon-map-generation/) *
Connor Clark Completed the implementation of the JAVA version. Amit Patel of Red Blob Games has completed the map creation algorithm perfectly, and the related algorithm can be found on the campus network website.
Hopefully it's of use to someone out there who needed it in Java like I did! * Note, the only island mode implemented is Radial. Implementing more is something for another day. * * FORTUNE'S ALGORTIHIM * * This is a java implementation of an AS3 (Flash) implementation of an algorthim * originally created in C++. Pretty much a 1:1 translation from as3 to java, save * for some necessary workarounds. Original as3 implementation by Alan Shaw (of nodename) * can be found here ( https://github.com/nodename/as3delaunay). Original algorthim * by Steven Fortune (see lisence for c++ implementation below) * * The author of this software is Steven Fortune. Copyright (c) 1994 by AT&T * Bell Laboratories. * Permission to use, copy, modify, and distribute this software for any * purpose without fee is hereby granted,provided that this entire notice * is included in all copies of any software which is or includes a copy * or modification of this software and in all copies of the supporting * documentation for such software. * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR AT&T MAKE ANY * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.T MAKE ANY * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.T MAKE ANY * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
8) Spatial meshing method
9_) Tried using spatial database
http://dev.mysql.com/doc/refman/5.1/en/spatial-extensions-in-mysql.html#gis-class-polygon
10) Found A BUG.
if(rs.getString(2).equals(pnt.getPlot().getPCI())){
sql1="UPDATE address SET belongcgi='"+pnt.getPlot().getCgi()+"' where id="+rs.getString(3);
// if(rs.getString(3).contains("498270")){
// System.out.println(sql1);
// }
11) Second verification , it is found that between several cells of the same site, the location cannot be correctly identified, and the occurrence rate is relatively high.
12) It was found that MY-SQL could not support complex spatial operations, and upgraded to P-SQL
Navicat for PostgreSQL[1] is a powerful database management and development tool specially designed for PostgreSQL. It can run on PostgreSQL database version 7.5 and above, and supports most of the latest PostgreSQL functions, including triggers, function retrieval, and permission management. Navicat's features not only meet all the needs of professional developers, but are also fairly easy to learn for newcomers to PostgreSQL.
13) On June 25, the spatial database was sampled for verification, and part of the verification found that Baidu map can correctly sprinkle points:
14) Large-scale verification through MAP-INFO
"very accurate"
15) Get Google offline map
16) Find the deviation correction algorithm
17) Verify the hierarchical relationship of multilateral rows
18) Complete the relevant design documents on September 30, 2014, the final version. !