The software I have always used is ESRI software. After all, they are the leader in the industry. From the ArcIMS4 I used at the beginning to the 9.2 I use now, after so many years of application, I found that there are not many advanced GIS functions that are really used on the server side. After all, network GIS cannot be expected to be as powerful as desktop programs. I think the advantage of the Internet lies in the rapid sharing of information, so looking at some current GIS websites, most of their functions are querying and information release. ArcGIS server is very powerful, but after using it for a while, I feel that it is not affordable for ordinary people.
ArcIMS has its own client releases: HTML thin client and Java thick client. But I always felt uncomfortable using it. Later, I simply wrote a client myself, and the basic functions of zooming in, zooming out, browsing and so on were implemented as if they were cats and tigers. I remember that in 2003, the initial map access was still a request that returned a picture. It was very laborious to use, the experience was very bad, and it almost drove people crazy, so the maps at that time were small.
Later, tile maps appeared. At that time, there were few such map websites on the Internet. At that time, most of them still used Java Applet plug-ins. There were still very few websites studying tile maps. I study tile maps on the Internet every day, drooling, and hope to convert my own map into a tile map. At that time, I felt that it would be faster to cut a large map into small maps and transmit them on the Internet. Because I didn't know other people's principles, I took a detour and changed my own map to a four-dimensional map. I cut the large map requested into small maps in real time and transmitted it to the client. Although it felt like it was faster. point, but the server takes a lot of time to cut the image in real time.
Then began a long period of repeated research, and finally discovered that other people's maps were pre-cut and stored by level. This is now an open secret, but in that era network GIS was not so prosperous, and information resources So rich. Next, we started to study our own graph cutting system and graph cutting program through the previous code accumulation. I was confused about the size of the picture at first. Then I compared various websites and finally settled on 256*256. The reason for choosing this number was simple. The computer screen at the time was 1024*768, which can be divided evenly. The picture cutting program starts with level 4 or 5, and later can be cut to level 12. This also gave me a full understanding of ArcIMS’s ability to withstand torture and survive under such huge, continuous, uninterrupted, high-pressure access. Of course, given the amount of data across the country, it occasionally crashes a few times, which is still okay. Understood. In order to increase the speed, of course multi-threading and cutting of irregular areas are used. In order to reuse the cut map and update the map data, design modifications have also been made in this aspect.
After having my own map cutting program, the next step is to need a WebGIS client. I ultimately fell in love with HTML when choosing a client. For JAVA, I need to download a plug-in. I have seen other Java websites and you have to wait for half a day to download the data. But then The speed is obviously faster, and it may also absorb the ideas of Tile.