Open Source GIS

C + + library Cgal for computational geometry

Open Source library for processing shapefile vector files Shapelib

Projection conversion proj. 4

Categories	GIS open source	GIS business software
GIS Desktop system	Udig, Ju MP, QGIS	ArcMap, ArcGIS
GIS analysis tools	GRASS, Ossim	ArcInfo, arcgrid< /td>
Geographic statistics	gnur	ArcGIS geostatistical Analyst
three-dimensional Virtual Globe	worldwing,earth3d,ossimplanet	arcglobal,google earth
spatial data Engine	PostGIS	ArcSDE, Oracle Spatial
relational database	pstgresql,mysql,ingres	oracle,db2
meta-Data Services	Isite	ArcIMS Metadata service
Map Service	mapserver, GeoServer	ArcIMS, mapguide Enterprise
grid Vector class library	GDAL, OGR
map projection	proj.4

Open Source (free) three-dimensional GIS (terrain, games) continued 1

Exploration of transferring from three-dimensional digital Earth publishing platform--introduction of several open source software

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

First write the idea:

To make a simple terrain walkthrough, consider developing directly in WW, or finding a development component in the form of a control.

The biggest expectations are:

1. Support Google's SketchUp, fast and intelligent three-dimensional modeling

2. Design mode to do a good job, preferably into a component form, and then develop the application

3. Better performance, for indexing technology, memory management and so on

4. Client independent version and client server-side coupling version optimization

5. The information of putting point server.

. NET Platform

1.WorldWind
The popularity is very high, the introduction is also very full. Link Here Nasaworld Wind
Currently divided into. NET versions andJavaVersion.
Development language: C#.java
Render mode: Directx,opengl (Java)

Advantages of WorldWind
WorldWind's software architecture should be very good, very good. Open design, make the expansion of WorldWind is very convenient and fast, there are hundreds of various plug-ins, many plug-ins are very interesting and practical. Using. NET and Java, it is relatively easy to study how it works.
The. NET version is relatively easy to delve into. The use of the Java version of the strict object-oriented approach makes the Java version leaner, but it's not as easy as. Net.
When I used to communicate, I often recommended worldwind. Very good, very strong.

This is described in. NET edition.

The following flaws cannot conceal the worldwind luster.

WorldWind's flaws
Overall architecture design is not a big problem. Mainly in the interior of a few
1. Slow speed. Several reasons lead to the slow problem of worldwind in actual use.
AImageData organization is confusing. Because WorldWind in the system design is to all kinds of industry data integration. Therefore, his design-time compatibility, resulting in the same area data acquisition duplication (accounting for memory resources), different data acquisition server speed inconsistent impact.
b C # exception. Catching an exception takes up most of worldwind time. Causes a serious pause in the display and data acquisition.
c) Dynamic generation of SRTM. It would be impossible if you wanted to download the SRTM like a drawing tool.
D queuedownload actual operation, once the exception and error, will result in data download pause. You need to readjust your perspective. and seemingly multi-threaded download, the actual effect is not obvious. This causes the display to appear to be paused.
2. Three-dimensional support capability is slightly worse.
Especially in the support aspect of the model, although there is a modelfeature class tothree-dimensionalShow. Here's the problem:
A) does not support Lod, although the. x file is designed to be supported, but apparently modelfeature does not support it.
b) The model shows drift. When you zoom in on the details, you'll find that the model is shaking up and down.
c) The model is not organized in tile form. Cache, memory, release and other methods are problematic.
3. Vector support
The WorldWind vector processing display class is rather confusing. The effect is not too good.
4.KML Support
Through a plug-in to support KML, but want to achieve googleearth add functions, but also need to do a lot of work.
5. Memory leaks
As a logical, C # does not have a memory leak. Where the problem occurs is that the QUADTILE.DISPOSE,D3D texture is not cleared. Making resources more and more expensive and slowing down
6.DEM Display defect
There is no smoothing between each tile, and there is often a deep pit, suspended.
7. Black Edge of image
Most worldwind software can see black edges and jagged edges that are visible on the edge of the image. The reason is JPG compression, the appearance of black infiltration led to black-edge sawtooth. Two solutions, a) the marginal strip uses PNG. (b) Strict data organization.

Domestic application of WorldWind
It can be said that many domestic experts have solved the above problems, and carry forward the advantages of WorldWind. Typical representative evglobe and so on. It's not easy, from a certain point of view, is really independent research and development.

Non. NET Platform

2.OSSIMPlanet
Link: ossimplanet
Development language: C + +
Render Mode: OpenGL
Compared with WorldWind, fame is too big. Although recommended, I generally do not recommend it, but he is really another very powerful open sourceDigital Earth。 The reason I don't recommend it is:
1) based on C + +. Light research knows it costs a lot of money, and it's not very suitable for domestic companies and units. The threshold is high, the time is long, the effect is slow.
2 less relevant information. It involves too many large open source libraries, while the domestic translation of the relatively small amount of information. Unlike WorldWind, get a set of source code can be opened dry.

But I like it very much, asTechnologyStaff, I recommend everyone to see. A lot of fun and knowledge in it. Very elegant, very content, worth collecting.

Ossimplanet Advantage
1) based on OSG (open Scene Graph), a very large and very industrial very mature open source software. This is very appealing to me. Many domestic companies, such as Xi ' an game can. Address: http://www.3snews.net/html/71/www.openscenegraph.org
Only OSG can list a lot of articles, the benefits of using OSG are listed. It takes a lot of space to describe clearly. We've taken it here.
2 smooth, fast and efficient display effect.
3 as a platform, he covers a wide range of content, such as you can use OSG to make comparable terrabuilder software. Support most vectors, images and model files with GDAL+OSG.
4 Perfect model support. Needless to say LOD, even the whole city is loaded with a little problem. A long time ago, there was a virtual city open source software called VTP.
5 specialization, indeed very professional.
6 script support. By using OSG's Osginterper (which is really fantastic), you can quickly bind Python,lua,javascript,ruby.
7 want to know more advantages, or go to the next to see it.

Ossimplanet defects
From a technical standpoint, there are few flaws in ossimplanet. However, as mentioned above, it takes a lot of investment and money to build your own products and solutions based on it. So its mishap is that it's not suitable for commercialization.

Ossimplanet Domestic Application
A few years ago, I talked to a development studio. They used the OSG and the digital Earth based on OSG development, referring to the ossimplanet but not directly used. Therefore, domestic applications, No.
This studio product is named Virtualterran. It turned out to be mapok (unsure, know, please contact me)

3.gps3d
Address: http://www.3snews.net/html/71/www.mgix.com/gps3d/
This open-source software should be more focused on GPS capabilities. It also contains some of the functions of the three-dimensional Earth.
Development language: C + +
Render mode: Opengl

This open-source software is very small and practical. As a technical reference, very good. The parts that can be referenced are the three-dimensional coordinates of the latitude, the WMS, the WFS remote call and the tile.

The disadvantage is not to say, after all, the direction is inconsistent, can not be used to request it platform.

4.earth3d
Address: http://www.3snews.net/html/71/www.earth3d.org
This open-source software is suitable for preliminary study of three-dimensional Earth. It shows the three-dimensional Earth and shows the border line.
Development language: C + +
Render mode: Opengl

As a preliminary study, it's still good. After all, the first step in the starting point is how to display three-dimensional Earth and post MODIS data. It can also show state boundaries. Very good reference.

5. More open source software
So far, I have found that the open source software is the above 4 kinds, if you know more, please tell me.

Summarize:
1.WorldWind is the most mature and most suitable for commercialization.
2. Technology optimal Ossimplanet