About Performance Tips and Guidelines
To achieve maximum performance from SkylineGlobe Server, it is important to adhere to the guidelines outlined in the sections below.
Hardware Considerations
Since SkylineGlobe Server relies on a hard disk cache, it is very important that the cache folder (configured via the Settings page) be on a very fast hard drive in order to optimize performance. For better cache management of a cluster, it is recommended to store the cache on a shared network drive.
In addition, since SGS also uses a memory cache to further optimize performance and to minimize unnecessary access to the disk cache, a large and fast memory will also improve performance when SGS is serving many layers. See “Software and Hardware Requirements” in the “Getting Started” chapter for information.
Determining an Appropriate Block Width for Feature Layers for TE4W Project
Block width is one of the most critical parameters in streaming a feature layer efficiently. In TE4W the block width value determines not only the block width of the stream requests sent from client to the remote server, like in TerraExplorer Desktop, but also the maximal distance from the camera above which the data disappears (i.e., Max Visibility Distance).
When a feature layer is loaded into TerraExplorer Desktop, the Suggested Block Width is set to ‘Auto’ by default. If the user does not set a block width manually, during the publishing process, the server automatically determines an appropriate block width value according to performance-related criteria. For optimized performance, however, it is recommended to manually set the block width in TerraExplorer Pro, prior to publishing the layer, or on the server side, after the layer was published. A layer’s block width should be calculated using the TerraExplorer Block Width tool. For more information about how to use the Block Width tool, see the TerraExplorer User Guide. After calculating the block width, you should enter it into the layer’s property sheet. See “Editing Layer Properties” in the “Working with Layers” chapter for more information.
There are two key factors in selecting a block width for a layer, for TE4W projects:
§ Density and Precision Level – The denser and more precise the data, i.e., the average number of points or vertices per area, the smaller the block width should be. Note that polygon and polyline feature layers are usually denser than point feature layers.
§ Layer’s Maximum Visibility Distance – The higher you want to view the data, the greater the block width should be.
In a case where the two factors contradict each other, i.e., you want to view very dense and precise data from a high altitude, it is advised to simplify the layer. For more information, see “Precision Level” and “Zoom Level” in this document.
The use of subdomains is highly recommended as a means of significantly increasing the number of concurrent connections to TerraExplorer for Web permitted by the browser. Since most web browsers only allow six simultaneous requests per domain, this limitation is likely to result in a significant queuing of resources that increases page load time. The creation of subdomains spreads the requests to several domains which are mapped to the your server or load-balancer. The number of permitted concurrent connections is directly proportional to your number of subdomains. See “Setting TerraExplorer for Web Settings” in the “SkylineGlobe Server Settings” chapter for information on how to enable subdomains.
If you have a very dense and precise data layer that you want to view from a high altitude, it is recommended to create a simplified version of the layer for viewing from a high altitude with a large block width. The original should be used for viewing from a low altitude using a small block width. For examples, see the table below.
The polygon or polyline features layer that represents rivers with a scale of 1:10,000 can be simplified to produce a 1:100,000 scale layer.
|
Layer |
Sample |
Max Visibility Distance |
Min Visibility Distance |
Suggested Block Width |
|
Rivers 1:10,000 |
|
40,000 m |
0 m |
4891 m |
|
Rivers 1:100,000 |
|
200,000 m |
40,000 m |
19 km |
If you want to view a layer’s features from several different zoom levels, divide the layer into multiple layers based on zoom level. Set a small block width for the low altitude layers, and a large block width for the high altitude layers. For examples, see the table below.
The World cities point features layer can be divided into two layers based on its population size:
|
Layer |
Max Visibility Distance |
Min Visibility Distance |
Suggested Block Width |
|
Population < 10,000 |
60 km |
0 km |
19 km |
|
Population > 10,000 |
800 km |
0 km |
156 km |
Altitude Mode
When creating a project for TE4W, it is recommended to set the layer’s Altitude Mode to “On Terrain” or “Absolute” rather than “Relative to Terrain”. This is recommended particularly for layers with dense features per block width. If “Relative to Terrain” must be used, it is recommended to decrease the block width.
Field by Attributes
No more than four Fields by Attribute classifications should be used per layer.
Recommended Browser
We recommend using the latest version of Google Chrome browser to browse TE4W.
DirectConnect
When working with a server cluster for load balancing and failover, DirectConnect uses the TerraBuilder fuser on each of the servers to distribute each TBP’s load. In this situation, multiple processes may simultaneously access the same source files on a shared local or network hard drive that is not fast enough, and a bottleneck can occur. See “DirectConnect Performance Issues” in the “DirectConnect” chapter for tips on avoiding this potential bottleneck.