DIGITAL EARTHS A COMPARATIVE OUTLOOK n n

DIGITAL EARTHS A COMPARATIVE OUTLOOK

n n Web mapping - Process of designing, implementing, generating and delivering maps on the World Wide Web GIS - The idea is that the users are able to access GIS functionality over the internet without having GIS expertise and purchasing expensive GIS software. Architectures of web mapping applications : n Server side application n Client side application Popular web mapping applications: Google Earth, Microsoft Virtual Earth, Google Maps, Yahoo Maps, Mapquest etc.

• A 3 D software model or representation of the Earth or another world. • Serve satellite & aerial imagery. • Provides user with ability to freely move around in virtual environment by changing the viewing angle & position. • Compared to a conventional globe they have additional capability of representing different views on the Earth’s surface i. e. geographical features, man-made features or abstract representations of demographic quantities such as population. • The first widely publicized virtual globe was Google Earth. Through Application Program Interfaces (API) and e. Xtensible Markup Language (XML)-based data specifications, developers and advanced users can create new functions & data.

• Google Earth: satellite & aerial photos dataset (including commercial Digital Globe images ) with international road dataset. • Microsoft Windows Live Local Virtual Earth 3 D: 3 D interface to the Windows Live Local maps and photos, runs inside Internet Explorer and Firefox • NASA World Wind: USGS topographic maps and several satellite and aerial image datasets, the first popular virtual globe along with Google Earth. • Arc. GIS Explorer a lightweight client for Arc. GIS Server, supports WMS and many other GIS file formats. • Others: Skyline. Globe, Earth. Slot and Celestia

• A virtual globe program - originally called ‘Earth Viewer’ and was created by Keyhole, Inc. • A client side server Internet mapping application • Degree of resolution - based on points of interest Most land covered - at least 15 mts resolution. Las Vegas, Nevada and Cambridge, MA - highest resolution at 15 cm. • Has DEM data collected by NASA's Shuttle Radar Topography Mission i. e. can view the Grand Canyon or Mt. Everest in 3 D • Supports managing 3 D Geospatial data through Keyhole Markup Language (KML). • Images generally current to within 3 years. • Place name and road detail vary greatly - most accurate in N. America and Europe. KML is an XML grammar and file format. KML file is processed by GE and Google Maps in a similar way that HTML and XML files are processed by web browsers. Like HTML, KML has a tag-based structure with names and attributes used for specific display purposes. Thus, GE acts as browser of KML files.

TILE MANAGEMENT OF DATA : used to provide high resolution satellite data with fast speed. At higher altitude fewer tiles of low resolution used to represent earth and these tiles divide further into sub-tiles of higher resolution as user zooms in to a particular location. CACHE: created on local machine - data for same place not required to be downloaded again i. e. in absence of internet connectivity, cached data can be viewed. AVAILABLE VERSIONS: 1. 2. 3. 4. Google Earth (free) Google Earth Plus (paid): higher speed, real-time GPS tracking, GE Pro (paid): annotations, more tools, import of GIS formats, create movies of virtual tours. Google Earth Enterprise (paid): most powerful, highly customizable – has its own GE server including a database with all geo-data & a powerful GE client. Includes services like geo-coding etc.

n n n n Errors sometimes occur due to technology used to measure height of terrain; eg. tall buildings in Adelaide cause one part of the city to be rendered as a small mountain, when it is in fact flat. Also, elevations below sea level are presented as sea level; i. e. Salton City, California; Death Valley; and the Dead Sea are all listed as 0 ft when Salton City is approx − 200 ft; Death Valley is − 286 ft; and the Dead Sea is − 1, 378 ft. The "Measure" function shows that the length of equator is about 40, 030. 24 km, giving an error of − 0. 112% compared with the actual value of 40, 075. 02 km Earth; For the meridional circumference, it shows a length of about 39, 963. 13 km, also giving an error of − 0. 112% compared with the actual value of 40, 007. 86 km. The Arctic polar ice caps & waves in the oceans are completely absent from the current version of GE. The geographic North Pole is found hovering over the Arctic Ocean. There is very low resolution coverage of the Antarctic continent (1 m resolution images of some parts of Antarctica were added in June 2007 for the first time). The tiling system produces artifacts near the poles as the tiles become 'infinitely' small and rounding errors accumulate. Cloud cover and shadows can make it difficult or impossible to see details in some land areas, including the shadow side of mountains.

National security and privacy issues n n Former Indian president APJ Abdul Kalam had expressed concern over the availability of high-resolution pictures of sensitive locations in India. The South Korean govt. expressed concern that GE offers images of the presidential palace and various military installations that could possibly be used by their hostile neighbor North Korea. The Area 51 base in the Nevada desert is clearly visible, with no evidence of intentional obstruction or blurring. The base's runways and even a number of planes are visible. As a result of pressure from the United States government, the residence of the Vice President at Number One Observatory Circle is obscured through pixelization in Google Earth and Google Maps.

n n A web mapping service provided as a part of Microsoft's Windows Live online applications services. The application is a typical Web 2. 0 application, providing the user experience of a desktop application, with functionality like drag and drop, smoothly opening menus etc. Though the application is web based, it is not independent of OS. 3 D visualizer, runs only under MS Windows. The resolution of the imagery varies from place to place - best available for USA, Canada, U. K. & Australia.

VIRTUAL EARTH GOOGLE EARTH Microsoft Windows XP (SP-2), MS Windows Server 2003/ Windows Vista. Windows (2000/XP/Vista), Linux and Mac. OSX, Linux, Mac. OSX Microsoft Internet Explorer 6 / 7 (now Mozilla Firefox) It’s a stand alone application. 1. 0 GHz processor (2. 8 GHz or faster recommended), 250 MB or more of hard disk space Unlikely to operate on older hardware configurations. 256 MB of system memory (1 GB recommended) Pentium 3, 500 MHz, 128 MB RAM 400 MB free disk space 32 MB video card (256 MB recommended) that supports Microsoft Direct. X 9, with 3 D hardware acceleration enabled 16 MB 3 D-capable graphics card. Resolution of 1024 x 768, 16 -bit High Color High speed / broadband Internet connection Network speed: 128 kbps

• GE downloaded & installed as client side application. • VE runs in Internet Explorer 6/7 (also in mozilla firefox now) & to view 3 D content an Active. X control has to be installed. Google Earth Interface after startup • GE initialization takes less time compared to VE. • Speed of zooming in to a location & display of appropriate data is faster in GE, although VE seems to be using tiling of data too. Microsoft Virtual Earth Interface after startup

GOOGLE EARTH MS WINDOWS LIVE LOCALVIRTUAL EARTH 3 D Introduction year 2005 2006 OS - Windows, Mac, Linux, Unix YES, NO, NO Program/data license Proprietary Propriety Multiple datasets No No Street map overlay Yes Some School, Restaurant and Hotel guides Yes No Transportation guides Yes Park guides Yes No Satellite and aerial image overlay Yes Weather map overlay No No Topographic map overlay Some No Real-time traffic report Yes No GPS-integration Yes No Distance measure Yes Drawing tools Yes No Movie maker Yes No

GOOGLE EARTH MICROSOFT WINDOWS LIVE LOCALVIRTUAL EARTH 3 D 3 D graphics Yes 3 D building models Yes Terrain models Yes Sea-floor models No No Planetarium Yes Day/night views Yes No Imagery of other planets No No Telescope/Sky mode Yes No Local sky view Yes No Online community user input Yes No Extensibility Some No Wikipedia integration Yes No

GOOGLE EARTH MICROSOFT WINDOWS LIVE LOCALVIRTUAL EARTH 3 D German, Dutch, English, Spanish, French, Italian, Japanese (with Help support in Arabian, Czechian, Korean, Brazilian Portuguese, Polish, Russian) English Yes (United States) Yes High resolution dataset areas Yes: Australia, Belgium, Canada, China, Denmark, France, Germany, Italy, Japan, Netherlands, Spain, United Kingdom, United States Some: United States, Canada, United Kingdom, Italy, France, Australia, Germany Street level address search areas Yes: Australia, Belgium, Brazil, Canada, China, Czechia, Danmark, Estonia, France, Germany, Hungary, Italy, Japan, Lithuania, Netherlands, Poland, Spain, United Kingdom, United States Driving direction areas Yes: Australia, Belgium, Canada, China, Danmark, France, Germany, Italia, Netherlands, Spain, United Kingdom, United States Some: United States, United Kingdom, Australia Business listing areas Yes: Australia, Belgium, Canada, China, Danmark, France, Germany, Italia, Japan, Netherlands, Spain, United Kingdom, United States No Hotel listing areas Yes: Australia, Belgium, Canada, China, Danmark, France, Germany, Italia, Japan, Netherlands, Spain, United Kingdom, United States No Languages supported 3 D buildings

n n n n Resolution of VE imagery better than GE for US, India GE imagery better & Europe both comparable. The labeling of context area, lakes, cities etc is better in VE. Even at largest scale the name of city is displayed at a corner in VE, whereas in GE only local streets & searched location are labeled. The Parks and recreational areas are labeled in the Virtual Earth even at very small scale, whereas in GE they are depicted as icons. The labels for water features too appear even at very small scale in case of Virtual Earth but in case of Google earth the features are labeled at large scale only. VE features LOCATE ME - which requires installation of an extra plugin; is used to locate the user automatically (by resolving the IP address). LOCATE ME is not much accurate i. e. testing its functionality in WP apartments, we were located in West Campbell. The layers can be turned On & Off as per the user’s choice GE thus enables user to choose the level of detail they require in terms of information. Whereas in VE all layers are controlled by the application and the user cannot control the level of information on screen. The user can create a polygon, path and image overlay in GE, whereas in VE no such functionality exists. With GE, once an image is downloaded, it takes much shorter period to zoom in or out ; Whereas VE 3 D reloads the images every time.

VIRTUAL EARTH GOOGLE EARTH TILING APPROACH for rendering aerial and satellite photos is very annoying one can see "chunks" of imagery load & unload as one moves along or zoom. GE's graphics engine refined over years & the technology seems more pleasing to eyes i. e. transitions between imagery is smoother. BIRD EYE VIEW offers aerial photos from 4 points. These images are much more detailed than aerial views from directly above buildings. No real equivalent to BE views. Not many data layers - have "Maps" & "Hybrid" layers showing information of roads, road labels, borders & country names. Also information for points of interests like restaurants, but not much information in this area. Huge no. of built-in layers, esp. points of interest : Airports, railways, ferry routes, restaurants, lodging, etc. Also, data from organizations like National Geographic Magazine, Discovery Channel, UNEP, AIA etc. Virtual Earth uses a Cylindrical Mercator projection. Uses the Cylindrical Plate Carree projection. (Reference datum for both - WGS 84) One unified Javascript API for both 2 D and 3 D maps - same javascript used to manipulate VE in 2 d is used to instantiate the map control & switch to 3 d. 2 different API’s exist : GE, a 3 d viewer & Google Maps, a 2 d viewer. Only Google Maps can be inside a webbrowers, while GE is a program. Focus of this comparison is from a user perspective, not a developer

Microsoft’s exclusive 45º “BE View”. Major U. S. Counties covered by BE’s view: Arkansas (Bentonville) California – Los Angeles, Orange County, & San Francisco Colorado (Broomfield County) District of Columbia – District of Columbia Florida – Duval (Orlando) Georgia – Fulton (Atlanta) Indiana – Marion (Indianapolis) Kansas – Wyandotte Kentucky – Fayette (Lexington) Louisiana – Orleans, Lincoln County Maryland – Baltimore City Massachusetts – Suffolk County (Boston) Minnesota (Dakota & Olmsted County) Nevada – Clark County (Las Vegas) New Mexico – Bernalillo (Albuquerque) New Jersey – Hudson, Lawrenceville & Trenton New York – Erie, New York, & Suffolk Ohio – Hamilton Tennessee (Coming Soon) Texas (Fort Worth) Pennsylvania – Philadelphia, Montgomery County Washington – King County (Seattle) BE view offers aerial photos from 4 pts which are much more detailed than the standard straight down aerial views (signs on top of buildings, advertisements, pedestrians etc are clearly visible). MS uses an aircraft equipped with a vexcel aerial camera to capture bird’s eye footage.

n Google's models look cartoonish because color & brightness don’t match the underlying imagery. The textures could possibly be shaded to match the histograms of the imagery beneath which would create more perceptual realism without loss of such custom quality. Perception within an environment is the difference between something looking realistic and non-realistic n MS's buildings better matched tonally to their surroundings & to each other, thus look better from a distance. The fact that they have modeled even minor buildings really makes cities come alive.

Comparison: Denver, Colorado capitol building in VE (AUTO GENERATED) to the HAND-BUILT BUILDING in GE Same building with cityscape in background & a close-up view. Note: Auto-generated textures in VE 3 D do not look very good in close-up view whereas there is a great detail in the hand-made GE model (esp. if you zoom in close). Part of the problem with VE 3 D view is due to MS's decision not to load too many texture details as it consumes a lot of memory space. On older machines, Google's approach will greatly overload the system causing much slower performance. In VE advantages of automatically generating 3 D buildings is to have vast majority of buildings modeled (more cities) at a better cost per city. Disadvantage is that the level of detail and accuracy (at least currently shown) in VE 3 D is lower when examined closely. http: //www. gearthblog. com/blog/archives/2007/05/virtual_earth_3 d_com_1. html

n n Google’s Hand-made approach doesn’t scale well in order to have 3 D buildings for each city. With free Google Sketch. Up 3 D modeling tool it is allowing people to upload models to their 3 DWarehouse. This is working well for larger & more interesting buildings but won't work for all the buildings. MS's approach (Auto-generation of 3 D buildings) is to take multiple aerial photos, using photogrammetry calculate size-shape of buildings, extract 3 D building models & use these photos to texture them. MS's huge investment to acquire & develop technology, buy camera assets, hire teams of aerial photographers to collect the data & the storage- processing costs will ultimately enable them to create building models for nearly all cities in a scaleable fashion.

In VE 3 D you can permalink any view as a URL and then send it, save it, or bookmark it. Better than making a placemark in GE, adding a snapshot view, and sending/ saving – for GE one has to download a KML file first to desktop where it sits superfluously until its trashed. Permalink is for consumers who regularly conduct the same searches or who want to share specific searches with others. By clicking the Permalink, a URL is created that can be used to return to MSN VE later and re-create map view and searches. Permalink can be bookmarked, e-mailed to a friend or copied into a clipboard.

Microsoft sees end users more as consumer that needs to be catered. VE 3 D's buildings, have been textured automatically and systematically. Google sees end user as content contributor Its default buildings are basic gray shapes, with end users encouraged to build their own textured masterpieces & share them through Google community and its 3 D Warehouse. Which strategy will prevail ? ? ? We think Google will eventually have to offer textured buildings by default.

n n n Microsoft has teamed up with 3 D Dassault Systemes (DS) to launch Microsft Virtual Earth – 3 DVIA. This free online application allows consumers to imagine and create realistic 3 -D models – for instance buildings and structures – then share them through Microsoft Virtual Earth and online communities. Users can design a 3 -D model of their house, favourite building or any structure, then select from different visualisation options, textures and colours to give their 3 -D model a style of its own. Users can then upload their 3 -D models to VE, specifying an address or neighborhood so they can experience the model within a real-life context.

Although MS still doesn’t have nearly the amount of coverage of world with high resolution aerial photos as Google, the amount of data they have added is significant. BE views in particular add several times as much photography for a given city as the standard straight-down views. So, for any given city where MS has BE views they have more aerial data than Google. And MS is adding cities with this data at an amazing rate. Thus, MS has decided advantage in terms of BE photography data, implementation for viewing it & for massive amount of new 3 D & aerial imagery they've been adding. Still this is not a major threat to the continuing popularity of GE as the overall user interface, smoothness, usefulness, and massive amounts of very useful data in GE continues to outshine what MS has built so far.

Google Earth has very little functionality of a commercial GIS - known as a layman’s GIS. n n n GE provides basic GIS functionality such as finding driving directions, locating a place & finding a business in a neighborhood. More experienced GIS users can create polygons, paths, place marks and perform image overlays - can be compared to digitization techniques offered by commercial GIS software’s but these features do not have any functionality other than visualization in GE. They can have a description attached to them but no attributes. The image overlays can be used to do visual interpretation of data but not spatial analysis. The paid GE Pro allows import of GIS data. The supported vector file formats are Map. Info (. TAB) & ESRI (. SHP). Raster file formats supported are TIFF (. tiff), National Imagery Transmission Format (. ntf), Erdas Imagine Images (. img). Although GIS data can be imported in GE but its attribute information cannot be edited after importing it which limits use of spatial data to just visualization. These files to be imported must have the projection information attached to it, although GE projects data on WGS 84 coordinate system. However, imagery without the projection information can also be imported in GE but the coordinates have to be manually edited. The supported file formats for this are Atlantis MFF Raster (. hdr), PCIDSK Database File (. pix), Portable Pixmap Format (. pnm), and Device Independent Bitmap (. bmp). Another interesting feature is the ruler, which can be used to calculate the length of a line, path and area of a polygon, circle - available only in paid GE Pro version. This feature can used to locate a nearest facility and get the distance to get there, manually. Whereas, a similar operation in GIS is totally automated. GE lacks data analysis aspects and unless incorporated GE will just remain a layman’s GIS.

ARCSCENE n Requires Arc. GIS Desktop and the extension 3 D Analyst. Entire 3 D scene is loaded into memory so it has memory limitations, thus can only be used to view smaller 3 D scenes. ARCGLOBE n Also requires Arc. GIS Desktop and the extension 3 D Analyst. Only loads current view into memory, thus supports loading large amounts of data. It has a single elevation surface and requires data to project it correctly on the globe. COMPARISON OF ARCSCENE TO ARCGLOBE: -Both can make 3 D fly-through animations. Arc. Scene has some additional layer animation capabilities, such as moving a layer in space. -Only Arc. Globe uses the Publisher extension to create a portable 3 D scene that can be read in Arc. Reader. -Both have access to the Arc. GIS Toolbox for analytical use. -Arc. Scene is more flexible in these areas and is better suited for underground visualization. Arc. Globe is good for terrain datasets. ARCGIS EXPLORER n It is a lighter tool for consuming content from Arc. GIS Server and running analytical tasks published by Arc. GIS Server.

Google Earth Vs Arc. GIS Explorer: Arc. GIS Explorer at startup n n • Both are client side application. n • In AGE double click of mouse doesn’t zoom in to a given location & the user can zoom in using zoom in slider. n • Initialization of AGE takes a longer comparatively. The speed of zooming in to a location is better in GE. • The resolution of imagery for US is comparable whereas for Europe & India, GE imagery is of very high resolution compared to very low resolution imagery of AGE. n n In AGE locations can be interactively located using a pointer tool & located address can be dragged into search box, instead of typing it. AGE has option to click on a location & find its address (currently available for US & Canada only). In AGE a line & a path can be measured, and latitude, longitude & elevation of a point can be found too. In AGE there is an option of finding a route with multiple stops in AGE, whereas no such option in GE. Water features & parks not labeled in AGE at any scale, whereas labeled at large scales in GE. The streets are labeled even at the largest scale in GE whereas in AGE street labels are turned off, much before the largest extent possible. Only 3 layers (imagery, transportation & boundaries) available in AGE, whereas in GE numerous layers available. GIS data can be added to AGE, whereas it can be added in the paid GE Pro version only. AGE has more GIS functionality than GE, although user interface & streaming of data is better in GE.

GE is user friendly application which is bringing basic GIS tasks to common internet users but it doesn’t have any spatial analysis functionality yet, which limits users. At present, the streaming of imagery & speed of browsing is better in GE & unparalleled. There is a long way to go, before any of these applications can integrate sophisticated GIS technology in web mapping with minimal cost for the user. n GE is just a visualization tool, however it has included new GIS functionality slowly & steadily ever since its launch (features like creation of polygon, path & importing of GIS data has been added in recent versions). Thus, it cannot be denied that Google Earth is being updated to compete with commercial GIS software’s at a very low price. Integration of complex GIS functionalities in web GIS is being actively pursued, and many competitor applications are coming up. Arc. GIS Explorer seems to be a good competitor for GE, as it integrates more GIS functionality.

Virtual Globe is Changing the Way We See the World

http: //www. gearthblog. com/blog/archives/2007/05/virtual_earth_3 d_com_1. html http: //en. wikipedia. org/wiki/Virtual_globe http: //en. wikipedia. org/wiki/Live_Search_Maps http: //en. wikipedia. org/wiki/Google_Earth AECnews. com. Google earth: The people's GIS. Available from http: //aecnews. com/articles/1050. aspx. Butler, Declan Butler - reporter. Available from http: //declanbutler. info/blog/? p=12. Earth, Google earth Commuinty. Available from http: //bbs. keyhole. com/ubbthreads. php/Cat/0. Earth, Google Earth User Guide. Available from http: //earth. google. com/userguide/v 4/ug_toc. html. Earth, Google Earth website. Available from http: //earth. google. com/index. html. ESRI. Arc. GIS Explorer Download page. Available from http: //services. arcgisonline. com/ 380/explorer/software/downloadpage. html. Flood, Brian Flood Blog. Available from http: //www. spatialdatalogic. com/cs/ blogs/brian_flood/archive/2005/08/19/72. aspx. Microsoft Virtual Earth. Available from http: //www. microsoft. com/virtualearth/default. mspx. Taylor, Frank. Google Earth Blog. Available from http: //www. gearthblog. com/. Wikipedia. Google Earth- Wikipedia. Available from http: //en. wikipedia. org/wiki/Google_Earth. http: //krottmaier. cgv. tugraz. at/docs/seminar/sem 2007_geoinfo. pdf

THANK YOU Presented by: Abhishek Kala, Bhavna Kalla, Vineeth Viswanathan