Open-source (free) 3D GIS (terrain, game) continued 1

 

Exploration from the 3D digital earth release platform -- Introduction to several open source software

Http://www.3snews.net/html/71/22271-21962.html

First write the idea:

If you want to make a simple terrain roaming, you may want to develop components directly in WW or in the form of a widget.

The greatest expectations are:

1. Support for Google's sketchup, fast and Intelligent 3D Modeling

2. Do a good job in the design mode. It is best to make the component form first and then develop the application.Program

3. better performance, index technology, memory management, etc.

4. Optimization of client independent version and client server coupling version

5. Store the server information.

 

. NET platform

1. WorldWind
Well-known and well-described. Here is the link for NASAWorld Wind
Currently, it is divided into. Net version andJavaVersion.
Development language: C #. Java
Rendering Method: DirectX, OpenGL (Java)

Advantages of WorldWind
WorldWind's software architecture should be very good and outstanding. The open design makes WorldWind extension very convenient and fast. Currently, there are hundreds of plug-ins, many of which are very interesting and practical. Using. NET and Java makes it easier to study its working principle.
The. NET version is relatively easy to go deeper. The strict use of object-oriented methods in Java makes Java concise, but it is not as easy as. Net in depth.
I often recommend WorldWind during previous exchanges. Very good and powerful.

The. NET version is described here.

The following defects cannot conceal the glory of WorldWind.

WorldWind Defects
The overall architecture design is fine. Main internal points
1. Slow speed. WorldWind is slow in actual use due to several reasons.
A) Images Data Organization is messy. WorldWind is designed to integrate various types of data in various industries. Therefore, the compatibility with the design results in duplicate data acquisition (memory resource occupation) in the same region and inconsistent speed of different data retrieval servers.
B) C # exception. Exception capture takes most of WorldWind time. This causes serious pauses in display and data acquisition.
C) dynamic generation of SRTM. If you want to download the SRTM file like a graph obtaining tool, it is impossible.
D) When queuedownload is actually running, any exceptions or errors may cause data download to pause. You need to adjust the angle of view again. The actual effect of multi-threaded download is not obvious. This causes the display to pause.
2. the 3D support capability is slightly poor.
Especially in terms of model support, although there is a modelfeature class 3D Display. There is a problem:
A) not supported. Although the. X file can be designed, it is obvious that modelfeature does not.
B) the model shows drift. When you zoom in to the most details, you will find the model shaking up and down.
C) The model is not organized in tile format. Cache, memory, and release all have problems.
3. Vector support
WorldWind's vector processing display class is messy. The effect is not very good.
4. kml support
You can use a plug-in to support kml. However, to add googleearth and other functions, you still need to do a lot of work.
5. Memory leakage
C # does not leak memory. The problem is quadtile. Dispose. the texture of d3d is not cleared. This increases resource usage and slows down
6. Dem display Defects
No smooth processing is performed between each tile, and deep holes and broken files often occur.
7. Black borders
Most WorldWind-based software can see black edges and serrations on the image edge. The reason is JPG compression, black penetration and blending, resulting in black-side sawtooth. Two solutions: a) the Edge Zone uses PNG. B) strict data organization.

WorldWind's domestic applications
It can be said that many experts in China have solved the above problems and carried forward WorldWind's advantages. Evglobe and so on. It is not easy. From a certain point of view, it is indeed self-developed.

Non-. NET platform

 2. ossimplanet
Link:Ossimplanet
Development language: C ++
Rendering Method: OpenGL
Compared with WorldWind, It is very famous. Although I generally do not recommend it for recommendation, it is indeed another powerful Open SourceDigital Earth. I do not recommend it because:
1) Based on C ++. Learning about it alone requires a lot of cost, which is not very suitable for domestic companies and organizations. High threshold, long time, slow effect.
2) there are few related materials. It involves too many large open-source libraries, and there is a lot of translation materials in China. It's not like WorldWind.Source codeYou can start it.

But I like it very much,TechnologyFor personnel, I suggest you go and see them. There is a lot of fun and knowledge in it. It is elegant, has a connotation, and is worthy of favorites.

Advantages of ossimplanet
1) based on OSG (open scene graph), an open-source software that is very large, very industrial and mature. This is very attractive to me. Many domestic companies, such as Xi 'an sai Neng. Address: http://www.3snews.net/html/71/www.openscenegraph.org
Only OSG can list a lotArticleThe benefits of using OSG are not listed. It takes a lot of time to describe clearly. We have brought it here.
2) smooth, fast, and efficient display.
3) as a platform, it covers a wide range of content. For example, you can use OSG to make software comparable to terrabuilder. Gdal + OSG is used to support the vast majority of vector, image, and model files.
4) perfect model support. Needless to say, there is no problem with loading the entire city. A long time ago, there was a virtual city open source software called VTP.
5) Professional, indeed very professional.
6) script support. You can quickly bind python, Lua, JavaScript, and Ruby by using OSG osginterper.
7) If you want to learn more about the advantages, go to the next page.

Ossimplanet Defects
Technically speaking, ossimplanet has almost no defects. However, as mentioned above, it takes a lot of investment and money to build your own products and solutions based on it. Therefore, it is not suitable for commercial use.

 Ossimplanet applications in China
I talked to a development studio a few years ago. They use the OSG and OSG-based digital earth. They refer to ossimplanet but are not directly used. Therefore, there are no domestic applications.
The product name of this workshop is virtualterran. Later it seems to have changed to mapok (not sure. Please contact me if you know)

 3. gps3d
Address: http://www.3snews.net/html/71/www.mgix.com/gps3d/
This open-source software should focus more on GPS functions. Of course, it also includes some functions of 3D Earth.
Development language: C ++
Rendering Method: OpenGL

This open-source software is very small and practical. As a technical reference, it is very good. You can refer to the longitude and latitude to three-dimensional coordinates, remote calls of WMS and WFS, and 3D display of tile.

The disadvantage is not to mention. After all, the direction is different and cannot be requested on the same platform.

4. earth3d
Address: http://www.3snews.net/html/71/www.earth3d.org
This open-source software is suitable for preliminary research on 3D Earth. It shows the 3D Earth and the border.
Development language: C ++
Rendering Method: OpenGL

As a preliminary study, it is good. After all, the first step at the starting point is how to display the three-dimensional Earth and paste the data with the modemdata. It also shows the border. A good reference.

5. More Open-Source Software
So far, I have found four open source software types. If you know more, please let me know.

Summary:
1. WorldWind is the most mature and suitable for commercial use.
2. Best technology ossimplanet