Virtual globes are known for their ability to render massive real-world ter- rain, imagery, and vector datasets. The servers providing data to virtual globes such as. 10 Exploiting Parallelism in Resource Preparation. Parallelism Everywhere Task-Level Parallelism in Virtual Globes. 3D Engine Design for Virtual Globes provides a fine guide to engine design and algorithms for virtual globe applications such as Google Earth packed with.
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3D Engine Design for Virtual Globes has 2 repositories available. Follow their code on GitHub. Jul 3, 3D Engine Design for Virtual Globes is a book by Patrick Cozzi and Kevin Ring describing the essential techniques and algorithms used for the. Supported with code examples and the authors' real-world experience, this book offers the first guide to engine design and rendering algorithms for virtual globe.
In virtual globes, we usually have a really big image that we want to wrap around an ellipsoid or sphere with displacements for terrain. The image is recursively divided into four, quad-tree style and streamed using out-of-core rendering. The book gives an overview of some state-of-the-art algorithms, but the implementation of Google Earth is still and probably will be a proprietary.
If I remember correctly, Rage uses some kind of ray-casting for terrain rendering…. Thanks Patrick! This link is also available from your blog-site.
[PDF] DOWNLOAD 3D Engine Design for Virtual Globes READ
Suffice it to say, the latest implementations may have changed significantly. And even my explanations are going to be so broad and potentially out-dated that no one should use this article as the basis for anything except intellectual curiosity and understanding. I just wanted to say that the book is not about Google Earth, but gives very comprehensive overview of techniques used to implement virtual globes.
I am seriously considering downloading this book or putting in a request for our university library to order it. There are some really cool public domain high resolution DEMs and aerial photography for parts of New Zealand that I have always wanted to convert into a cool demo.
Also my current project on modelling cell phone networks would look really cool overlaid onto a 3D map…. Although the globe giving the points P0 and Q0. Moreover, two other Firefox has its own event implementation, our experience 0 0 points Pk and Qk are produced when the user continues to of date is that it does not work properly. Thus, an open drag their fingers.
Then, the new camera position is es- problem is to handle multitouch event in web browsers. The Open Geospatial Consortium OGC , an international When a tile must be subdivided attendant to some error cri- voluntary consensus standards organization, works to en- teria, four new tile children are required and so four server able more usable and useful geographic information in GIS WMS requests are triggered.
To select an appropriate server, related applications. For example, users can access the enor- a list is visited sequentially, until a server is reached that to- mous amount of available internet data layers by means of tally covers the bounding box of the tile. The first one 4. The second one is the Virtual Earth Tile definition of any WMS request which is then simply encap- Server, that is used for higher detail images.
This server sulated in a URL address and finally launched to the server is the backend for Microsoft Map Web services. It is not a via, for example a web browser. This example shows the standard WMS server, but works with fixed location images request of a tile image corresponding to the island of Gran of predefined size.
Obviously, each tile is not subdivided into its four children until all of their tex- data. It is very powerful and rich in multiple configuration tures have been achieved. Experiments have validated this options. However, our tests revealed that MapProxy may technique for several bandwidth connections, as an adequate originate time-consuming tasks, especially for mobile device navigation experience. In addition, one needs to explicit the list of WS servers to be accessed in the file configuration, which is not It is worth noting that some WMS server does not allow appropriate when our requirement is that users add and re- many simultaneous requests.
Thus, only the highest priority move WMS layers at runtime. Thus, a PHP script is imple- tiles according to distance from the observer are requested mented, producing a simple solution to overcome security to the server.
Moreover, no more than 50 tiles are allowed domain issues. It was also noted that some WMS servers did not seem to accept resource requests from web browsers.
To solve that 4. They are the basis of client-server communication This is an example of the versatility of the PHP scripts. This leads us to asynchronous Tiles are cached to disk to improve performance.
Thus if threads for network operations. The network connection au- a tile is removed from the quadtree, because the observer tomatically schedules the downloading of images and then has navigated to a different place, on return to the same callbacks are received as it progresses. Using asynchronous place, the texture is first searched in the cache before sending operations reduces the concern with respect to blocking or the request to the WMS server.
This allows efficient and delaying the virtual globe application and with creating mul- fast visualization as has already been proved in many other tiple of requests. A queue per operation is created that can visualization systems. The globe engine thus developed creates a temporary memory Less intuitive is the treatment of requests on HTML browsers, cache where the downloaded tile images are stored.
Book Review: 3D Engine Design for Virtual Globes
With a web browser it is possible to need to edit images as in the access to particular fields, op- use the existing browser mechanisms of web cache instead. We use freshness, where a max-age directive is set up indicating for how many seconds the response is fresh. Transfers and security domains Cross-domain security has to be dealt with when download- The Following PHP code is used to request the browser to ing and applying WMS textures to our globe.
The problem place an image on its own cache. The problem is that it is con- sidered unsafe for a client to attempt to request server data if! This proxy can be implemented in many ways: from it impossible to use normal compressed image formats such a simple PHP script, to systems developed specifically for as PNG or JPG that require hardware-dependent compressed these situations, such as the MapProxy 12 tool. For each so- formats instead. For example, the iPhone only supports a lution, the advantages and disadvantages must be evaluated specific type of compression called PVRTC, supported by a to come to a decision on the best option.
Cozzi Patrick, Ring Kevin. 3D Engine Design for Virtual Globes
The iPhone SDK only comes with a command-line program that 4. This server uses a specific format iPhone project. BIL to return the elevation data. Every pixel in the result- ing image named height map is a 16 bit signed value, that Obviously, this solution of command-line compression is not indicates the height in meters of the corresponding point.
With this image, each compress images on the fly. For this reason, we read the pixel vertex on the mesh is translated in the normal direction to data at the original uncompressed 24 bit color values, and the globe surface as many meters as indicated in the height convert them to 16 bit representation.
This simple image map. After several experimental results, we have seen that compression has proved to be successful on the tested devices the precision of height maps is slightly inaccurate. To obtain without detriment of visual quality. After several tests on various different smart- includes an area three times larger in both dimensions.
Some WMS textures in- clude this channel to indicate that some areas on the maps must not be displayed, see Figure 8. In these cases, two tex- tures are required for each tile. For this b Gran Canaria height fields reason, the merge of both textures is produced in the CPU, to maintain the maximum value of textures in the GPU memory.
Then, this text data is translated to the cur- tual globes rent character set used by the browser. Therefore, there is Op. This strategy would and also from popular iOS and Android Markets.
The near make it possible to receive binary information and would future of Glob3 Mobile lies in adding the new and demand- solve cases such as BIL files.
The en- 5. We describe here the main soft- ware components for an easy design and implementation of Acknowledgements a virtual globe together with user-specific enriched features This work has been supported in part by Spanish firm IGO on iOS, Android and WebGL compliant browsers. Careful attention has been ].
Bell, F. Kuehnel, C. Maxwell, R. Kim, droid platforms. We have tested the application on a dozen K. Close Preview. Toggle navigation Additional Book Information. Topics covered include: Rendering globes, planet-sized terrain, and vector data Multithread resource management Out-of-core algorithms Shader-based renderer design. Implementing a Message Queue.
Reviews 3D Engine Design for Virtual Globes provides a fine guide to engine design and algorithms for virtual globe applications such as Google Earth … packed with formulas and details on simulations, visualization and GIS applications … a winner for any technical collection. Request an e-inspection copy.
Share this Title. Recommend to Librarian. Related Titles. Game Engine Gems 2. Shopping Cart Summary. Items Subtotal. View Cart. Offline Computer — Download Bookshelf software to your desktop so you can view your eBooks with or without Internet access.Thus if threads for network operations. For each tile T the geodesic distance dT is calculated from this point to the centre of the tile. Suffice it to say, the latest implementations may have changed significantly.
The value of a single voxel at a certain time and location or the values of all the voxels along a profile are readable thanks to an implemented pop-up window with a 2D viewer appearing over the main map. For this reason, we read the pixel vertex on the mesh is translated in the normal direction to data at the original uncompressed 24 bit color values, and the globe surface as many meters as indicated in the height convert them to 16 bit representation.