VirtualGeography is a collection of interesting snippets from all over the shop, dealing with industry issues concerning the computer based visualisation of geography and a few other associated (or otherwise) interesting bits and pieces. You are receiving this either because you subscribed to VirtualGeography or you have had recent dealings with VizMAP Pty Ltd. If you do not wish to receive further instalments of VirtualGeography, just click on the unsubscribe link at the bottom of this e-mail. 

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So, g’day to all you enthusiasts requiring to visualise and simulate both urban and rural geographic information (GIS), cartography, photogrammetry, remote sensing, digital elevation modelling (DEM) and general mapping.

By the spelling of "Visualisation" you may have already guessed that we’re not US based – that’s a good thing, or at least not a bad thing. This comes to you from Mooloolaba on the Sunshine Coast of Queensland, Australia, where it’s beautiful one day and perfect the next. The link between visualisation and mapping may seem a little esoteric if this is your first encounter with this sort of stuff, but let me tell you, the bond is significant… but enough of that: on with the show… I hope you like it. Any feedback you might have is highly appreciated. E-mail me here to make your comments. Enjoy… Graeme Brooke VizMAP Pty Ltd

P.S. You’ll need an active internet connection to view any images that are in the content. We’ve done it this way to keep the size of the e-mail to a minimum.

The OOS Repository Editor was originally developed to provide WARSIM database producers with an easy-to-use database intensification environment for off-the-shelf WARSIM geotiles. This system is now being extended to support engineering efforts for OOS database repositories. 

The use of a Unified STF (SEDRIS Transmittal Format) containing original source data for the WARSIM geocell, combined with editing tools based upon TerraSim’s TerraTools project editor, currently allows end users to interactively customize or refine existing databases and produce an updated Unified STF on a geotile basis.

TerraSim will also demonstrate TerraTools®, the core environmental database generation system, and TerraTours™, a real-time situation assessment and information fusion viewer for high fidelity urban operations. TerraTours integrates 3D visualization with interactive query to deliver organization and display of a variety of information sources, including still imagery, CAD drawings, audio, and video that are linked automatically during the database construction process or directly by the end user through the visualization.

For more information, visit TerraSim’s SEDRIS Associate page, or visit booth the TerraSim booth
during the SEDRIS Technology Conference.

The situation is exacerbated because of mobile graphics solutions’ relatively lower performance. Gamers will likely need to reduce graphics features or resolutions in some 3D games to achieve playable frame rates. The newest laptop graphic solutions are roughly equivalent to midrange solutions on desktop systems. 
 

There are good reasons for this: Typically, mobile graphics chips have more robust power management features than their desktop brethren. Also, mobile GPUs are often bundled differently, often including memory and core on a single multi-chip package. Finally, power constraints preclude dropping in a power-hungry, high end desktop GPU. If you’ve ever seen the cooling solution on a GeForceFX 5950 or Radeon 9800XT, you can appreciate the problem. 

Manufacturers have had to make additional compromises in the name of power usage and thermal dissipation. ATI’s desktop 9600 Pro’s clock rate, for example, is 400MHz core / 300MHz memory (600MHz DDR). The desktop GeForce FX 5650, meanwhile, runs at 400/400 (800MHz DDR memory). But the clock rates of the Mobility Radeon 9600 on the Dell Inspiron 8600 are 337MHz core / 243MHz memory (486MHz DDR). The Quadro FX 700Go, which is based on nVidia’s 5650 architecture, clocks at 295/295. So, the clock rates are noticeably lower, which affects performance. With this in mind, let’s take a look at the contenders.
 

TerraTours provides access to a variety of web-based media including audio, video, still images, and web pages, presented as graphical links in a real-time 3D display. In addition, all geospatial attribution present in the source vector data used to construct the 3D visualization
is available for query and display.

TerraTours is a functional extension of TerraSim’s highly successful TSGFly™ real-time display technology, allowing customers to execute a mixed 3D GIS deployment strategy, sharing a common functional architecture. As with TSGFly, TerraTours is optimized to provide high-performance graphics on low-cost Windows® workstations.

TerraTours employs TerraSim’s GISLink™ technology, which allows users to link arbitrary multimedia objects to specific 3D geographic features in the visualization. GISLink delivers flexibility in link creation, allowing users to assign multimedia to geographic features during database creation, or dynamically, within the TerraTours display and query environment.
 

By using TerraTools, TerraSim’s visualization construction toolset, rapid update to complex urban areas can be easily achieved as a natural consequence of GIS maintenance, by leveraging the reusable process flow graph architecture of TerraTools. Improvements to your GIS source base, including links to multimedia, can automatically be compiled into an updated TerraTours display and query environment.
 

TerraTours offers a basis for delivery of highly configurable real-time viewing solutions for an extensive range of end-user applications, including urban redevelopment and site planning, situation awareness for industrial security and site monitoring, as well as homeland defense applications.

The DEM

This data set is a digital elevation model (DEM) product that populates the GLOBAL Terrain product catalog. The DEM products are generated using the Intermap STAR-3i airborne interferometric synthetic aperture radar (SAR) system mounted in a LearJet 36A aircraft. 

The GLOBAL Terrain Digital Surface Model (DSM) data files are digital representations of cartographic information in a grid form. DSMs consist of a sampled array of elevations for a number of ground positions at regularly spaced intervals. These digital data files are produced by Intermap Technologies Inc.(Intermap) as part of the GLOBAL Terrain product line and are licensed in 7.5-minute tiles for areas located between 0 and 56 degrees North/South. Data for locations above 56 degrees North/South are licensed in 15-minute by 7.5-minute tiles. 

GLOBAL Terrain DSM products represent the first reflective surface as illuminated by the radar. Accuracy statements are based on areas of moderate terrain. Diminished accuracies are to be expected in areas of extreme terrain and dense vegetation. 

GLOBAL Terrain DSMs are produced within four classes of vertical accuracy. GTF DSMs have an accuracy of 0.5m Root Mean Square Error (RMSE) or better. GT1 DSMs have an accuracy of 1.0m RMSE or better. GT2 DSMs have an accuracy of 2.0m RMSE or better. GT3 DSMs have an accuracy of 3.0 RMSE or better. No in-scene ground control points are required for GT2 and GT3 products provided that the DGPS ground station is within 200 km of the data acquisition area. The GTF and GT1 products do require in-scene ground control. 

The DSM data for 7.5-minute units correspond to the USGS 1:24,000 and 1:25,000 scale topographic quadrangle map series for available areas in the United States and throughout the world. Each 7.5-minute DSM is based on 5- by 5-meter, or 10- by 10-meter post spacing using the Universal Transverse Mercator (UTM) projection. Each 7.5- by 7.5-minute tile provides full coverage with overlap into adjacent tiles.

The Orthorectified Radar Image

This data set is an orthorectified radar image (ORRI) product that populates the GLOBAL Terrain product catalog. The ORRI products are generated using the Intermap STAR-3i airborne interferometric synthetic aperture radar (SAR) system mounted in a LearJet 36A aircraft.

The GLOBAL Terrain ORRI data files are digital representations of the radar response signal. ORRIs consist of a georeferenced pixel for a number of ground positions at regularly spaced intervals. These digital data files are produced by Intermap Technologies Inc.(Intermap) as part of the GLOBAL Terrain product line and are licensed in 7.5-minute tiles for areas located between 0 and 56 degrees North/South. Data for locations above 56 degrees North/South are licensed in 15-minute by 7.5-minute tiles.

GLOBAL Terrain ORRI products represent the first reflective surface as illuminated by the radar. Accuracy statements are based on areas of moderate terrain. Diminished accuracies are to be expected in areas of extreme terrain and dense vegetation.

The ORRI data for 7.5-minute units correspond to the USGS 1:24,000 and 1:25,000 scale topographic quadrangle map series for available areas in the United States and throughout the world. Each 7.5-minute ORRI is based on 2.5m pixel resolution using the Universal Transverse Mercator (UTM) projection. Each 7.5- by 7.5-minute tile provides full coverage with overlap into adjacent tiles.

The original ORRI is unenhanced and may appear dark when viewed. Both the original ORRI and an ORRI with a customized linear stretch enhancement are provided. The stretched ORRI will appear brighter and is easy to view without additional enhancements.

The Vis/Sim Database

The vis/sim database was quickly and easily constructed using the new TerraTools v.2. OmniWizard. 

Sample still images from the completed dynamic visualisation database are displayed here. An active internet connection is required to be able to view these scenes.
 

But some photography enthusiasts are uniting them to produce some spectacular images and to give a unique perspective on many everyday places and subjects. Aerial photography dates from the 1860s and kite-assisted photography is almost as old. 

But more recently the web has helped it grow by making it much easier for people to share knowledge, tips and the pictures they have taken. 

Rig and roll 

Peter Bults, who runs an online encyclopaedia for kite aerial photography, says it is much less of a struggle to get into now. There are more and more almost ready-to-fly systems available, developed by kappers (kite aerial photographers), he says. 

A typical kite aerial photography kit involves a single string nylon kite with a wingspan in excess of two metres. Anything smaller would not be able to lift a digital camera. Many kappers build their own cradle out of aluminium or carbon fibre to hold the camera and use radio control systems from model aircraft to snap a shot once the camera is airborne. 

Kite photography gives a fresh perspective 

Although there are no commercial rigs available some kappers will make rigs for others if asked. Some kappers still use film, but many are turning to digital cameras because they can take more shots before they need to be retrieved. Kappers tend to use mid-priced, five or six megapixel cameras and are not interested in all the features found on more expensive devices. 

Many simply add weight with features, such as a flash, that are largely useless at altitude. One of the skills that is definitely worth mastering is kite flying, says Mr Bults. Some of the most interesting shots are only going to be available in cities and urban areas where flying a kite is a real challenge. 

"It’s not very interesting to fly it over a beach or farmland. The interesting thing for kite flyers is that you move into towns and that makes kite flying very difficult." 

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They’ve been working on some really nifty virtual reality simulators, the case in point being to incorporate Armed Reconnaissance Helicopters into exercises (from the data fusion point of view). Most of the people they employ on this sort of thing are ex- (or future) computer game programmers. Anyway, as part of the reality parameters, they include things like trees and animals. For the Australian simulation they included kangaroos. In particular, they had to model kangaroo movements and reactions to helicopters (since hordes of disturbed kangaroos might well give away a helicopter’s position).

Being good programmers, they just stole some code (which was originally used to model infantry detachments reactions under the same stimuli), and changed the mapped icon, the speed parameters, etc. The first time they’ve gone to demonstrate this to some visiting Americans, the hotshot pilots have decided to get "down and dirty" with the virtual kangaroos. So, they buzz them, and watch them scatter. The visiting Americans nod appreciatively… then gape as the kangaroos duck around a hill, and launch about two dozen Stinger missiles at the hapless helicopter. Programmers look rather embarrassed at forgetting to remove that part of the infantry coding… and Americans leave muttering comments about not wanting to mess with the Aussie wildlife…

As anaddendum, simulator pilots from that point onwards avoided kangaroos like the plague, just like they were meant to do in the first place…