Army 3D Digital Sandbox Electronic Sandbox Virtual Reality Simulation Deduction Big Data Artificial Intelligence Development Tutorial Lesson 15
No matter what GIS platform is now, the first thing to solve is the problem of data sources, because GIS without data is an empty shell. Below I will introduce some of the current mainstream data acquisition methods.
The way to understand is as follows: my opinion (mainly for some satellite images on the Internet, and some vector tile images)
https://blog.csdn.net/m0_37738114/article/details/80452485 Before that, let’s take a look at this. The above introduces the coordinate system used by the current mainstream Internet platforms on the Internet. And this correction method that is currently used in many ways https://www.wandouip.com/t5i238176/ However, the accuracy of the correction algorithm is explained in detail above, which means that there are problems with using correction algorithms to correct corrections. Of course, it is definitely no problem to manually add a little offset on this basis in a local range. Problems arise when the scope of responsibility increases.
For some occasions where confidentiality is required, the map needs to be used offline. The general method is to use a downloader to download the tiles and then assemble them into a whole picture, then import them into the slicing system of the corresponding platform, and then regenerate the data required by the corresponding platform. Others are tiles that can be directly released for download. No one can escape the accuracy problem of converting gcj02 to gw84 in wide range mode.
Let me talk about how to deal with this problem in MTGIS:
1. First complete the access to the Internet WMTS tile. . However, it currently only supports EPSG: 900913 tiles cut (basically all except Baidu).
2. There are two ways to correct the deviation: one is to convert the vector data into GCJ02 and then put it on the map. If there may be accuracy issues in a large range (using algorithms), use the API interface of Baidu or Amap. Changing the vector into GCJ02 requires that it cannot be separated from the Internet. The accuracy is guaranteed and cannot be used offline. . . . . The problem is that in MTGIS3D we use the lookup table method to complete the correction. This method can be separated from the Internet and the accuracy is guaranteed. And the method is used to directly correct the GCJ02 base map, which is equivalent to directly correcting the GCJ02 data to the GW84 series. Can directly connect GPS and existing GW84 vector data.
3. The map data supply plug-in has been completed. The GCJ02 data set on the Internet can be browsed directly through configuration and cached locally during the browsing process. It has been automatically converted to 84-series data in the background (can be used offline in the future). Currently, the tests that have been supported include Google Map (not Google Earth, there is a difference between the two) and Gaode-based maps.
4. Conversion of front-end positioning system. Next we will launch mobile APP, which uses Baidu Status SDK (including base station positioning). The output coordinate is GCJ02. We use the table lookup method in the background to convert the coordinates transmitted from the mobile phone into the 84 coordinate system.
Using the above 4 points, users can have global 84 series satellite data and use GPS.
Written at the end: Currently, many people use open source systems such as CESIUM. When they are disconnected from the Internet, data is a headache, but it is OK in a small range. Just on a large scale. . . Here, the Internet data plug-in in the SDK is used. Without doing any work, you can have global data in an offline environment, and it has been corrected and can be used for GPS.
Newly added properties in MTGIS3d control
public bool ShowFLGrid;//Whether to display the square grid .
public bool Atmosphere;//Whether to display the atmosphere. (Because WPF does not support the shader function, the effect is...)
