Skip to main content

Posts

Showing posts from 2010

Integrated GPS cameras...

          GeoSpatial Experts has introduced three new GPS Camera bundles designed specifically for geotagging and mapping digital photographs. The firm now offers its popular GPS-Photo Link 5.0 photo-mapping software with the new Ricoh G700SE, Sony A55, and Casio EX-H20G GPS cameras.           All of the GPS cameras below will provide you with geotagged photos, additionally, some can also offer the ability to capture the direction the photo was taken with a built-in compass, or the ability to collect attribute data in the field. WiFi and Bluetooth will allow you to communicate with laser range finder equipment to measure exact distance from the photographer to the item being photographed. Some GPS cameras provide a ruggedized camera to withstand harsh conditions.            In 2007, Ricoh introduced its 500SE model as the first GPS-equipped SLR designed for GIS data collection, and the new G700SE is more compact and offers many upgrades. Fully ruggedized and waterproo

GIS Technology to identify all properties in BBMP Limits

          The Bruhat Bangalore Mahanagara Palike (BBMP) has for the last two years, been in the process of conducting a massive exercise to map the 13.87 lakh properties in the 198 wards in the city. Geographical Information System (GIS) has proven to be an effective tool for analysing and displaying thematic maps of all the roads for proper evaluation and correction of zones.            As of now, 11 lakh properties have come under the tax net. The aim of this programme, which is perhaps the first such exercise being conducted in the country on such a large scale, covering 800 square km, is to bring all properties under the tax net and ensure that the BBMP has accurate information pertaining to the properties’ dimension, built-up area, land use and classification. The process of validation of GIS maps will be completed in January 2011.           The process uses satellite digital maps of the BBMP area to generate a vector map from the information obtained. These high r

GIS Viewed as Strategic Economic Development Tool in India

          The Asia Pacific region is in the midst of rapid change. This change depends on information. Much of this information is concerned with questions that are fundamentally geographic in orientation -- such as the spatial patterns of households or businesses, and proposed infrastructure facilities within a community. The role of geographic information in economic development dominated the proceedings of the second ESRI Asia Pacific user group meeting earlier this year. The meeting was hosted by NIIT Technologies. It drew more than 1100 delegates from across the region to New Delhi for two days of discussion.                        The meeting was held at the right time. Historically, India has enjoyed a reputation for capable data conversion. But now, Indians are creating centres of excellence for GIS project development. Dave Byers, ESRI's Asia Pacific regional manager, told the meeting that there was a clear trend of increased GIS deployment on the

Merry Christmas Everyone

            Another year has come and gone and it is that time of the year again, when you are thankful for everything merry and bright. May this Christmas be bright and cheerful and may the New Year begin on a prosperous note! Wishing you all a Merry Christmas !

On-click polyline

    Following up on the last example where we saw how to add a hard-coded polyline to our map, today we will see a more user interactive polyline example. In this example we will discuss on-click polyline! What you need to do is, copy the following code into a txt file and save it with dot html (.html) extension and then view it in your browser. So here goes the code!     The output of the above code will be a map centred at Mysore. Click on the map for the first time and a marker will appear there. On the next click, another marker will appear with a polyline between the 2 markers. This will continue for all further clicks and here you have your "On-click polyline" running! The map looks something like seen in the image below!     The next step to this code will be creating a polygon. We will see examples to create polygons on the map at a later stage! If you have any queries or suggestion, please drop a comment here or feel free to send me a mail .

Total Lunar Eclipse

         On 21st December 2010 last eclipse of the year which is Total Lunar Eclipse would occur. The eclipse will be visible in the region covering Europe, West Africa, the Americas, the Pacific Ocean, eastern Australia, the Philippines and eastern and northern Asia. Whereas this eclipse is not visible in India. Timings As Per Indian Standard Time (IST):          Broadly speaking the Eclipse begins at 10.58 a.m. IST passing through various phases and ends at 4. 36 p.m. IST. However the Umbral phase is generally considered as actual eclipse for various ceremonies by general public. i.e. Moon enters the Umbra (dark part of earth shadow ) at 12.02 p.m IST and leaves umbra at 3.32 p.m IST. Importantly Moon enters totality phase at 1.10 p.m noon and ends at 2.24 p.m.          We can watch the lunar eclipse live with the Slooh Telescope in Google Sky! Follow these steps: 1. Open up Google Earth (download it if you don't have it yet! http://goo.gl/iGb66 ). 2.

Fun with GPS!

            There seems to be a plethora of games and alternatives emerging to take advantage of the affordability of handheld GPS units. In a previous article on my blog, the high-tech treasure hunting game of Geocaching was discussed. Learn about more ways to use the surface of the earth as your gameboard. This article will provide an overview on two more GPS-based ideas: Geodashing and GPS Drawing. Geodashing:             G eodashing is a game in which players use GPS receivers on a playing field that covers the entire planet. The waypoints, or dashpoints, to be reached are randomly selected. The win goes to the one who can get to the most dashpoints; i.e. if you can get to them at all! Each game has a new set of dashpoints making each game completely different and unpredictable. Click to know more of this interesting game... GPS Drawing:             The GPS Drawing Project seeks to display GPS-based artistry created by navigating through

GPS Drawing...

            "Digital mark making with satellite navigation technology" is how you can define GPS Drawing Project!             Jeremy Wood is a multi-discipline artist and map maker whose diverse work is an expression of the poetry and politics of space and reflects upon how we treat our travels and interact with location. In October 2000 he began to explore GPS satellite technology as a tool for digital mark making on water, over land, and in the air. He makes drawings and maps of his movements and records all his daily journeys with GPS as an ongoing personal cartography.            Wood has conducted numerous GPS drawing and mapping seminars and workshops in schools, museums and galleries. His work is exhibited internationally and is in the permanent collection of the University of the Arts and the Victoria and Albert Museum in London. To know more about him and to view his GPS drawings you can visit his website .            To know more about the GPS mapping pro

Geodashing...

            Geodashing!?!? Sounds something similar to Geocaching right? Well, it is! Geodashing is very similar to Geocaching in the sense that people are searching for a particular spot with only a set of coordinates as their clue.             Here's how it works. In each game, a large set of waypoints, called dashpoints, from all over the world is posted on the Web. Dashpoint locations are chosen at random by computer, with all the unpredictability that presents. Dashpoints might be in suburban neighborhoods or in the middle of wilderness areas. Then, the race is on to see who can reach the most dashpoints before the deadline.             Geodashing players can participate as individuals or as teams of up to five players to increase the number of dashpoints reached. The competition is friendly and teamwork helps to get high scores, so put your online acquaintances to good use.             Because the dashpoints are spread all over the world, it doesn't matter w

Custom online cards from Google Maps...

            Share a message of holiday cheer with custom online cards from Google Maps this New Year! Think Green, Go Green this New Year. Save paper and that too with a difference! This new year you can send your friends, family and loved ones an e-card which is out of the box!             You can choose from 10 different online holiday cards and add your personal message. Now, after reading this you will think what's so different here! The surprise is yet to unfold...You can include specific directions, a Street view image or your favorite place on the inside of the card!             So now planning your New Year party will become easier. You can send an e-card with directions from your friend's place to the place where you are hosting your New Year party! Won't that be fun!             You can send your personalized Google Maps New Year Cards from here !             Warm wishes for a great holiday season and wish you a Happy Mapping Year...

--- Polyline ---

    We have seen a number of examples for markers and info-windows. We can definitely move ahead now with other things in Google Maps API v3. Today we will have a look at polylines. Today's example will show a hard-coded polyline, but later on we will have a look at creating polylines on the fly. We will also create polygons and calculate the geographic area and more but at a later stage!     Let us now first have a look at today's polyline code. You just need to copy and paste the code that follows into a text file and save it as .html. Double-click on the file and you will be able to see the map in action.     The output of the above code looks as seen in the result section above! The code is very simple and does not require any special explanation I guess! We have made use of an array to store the co-ordinates that form the polyline on the map! Rest is mostly as usual!     Please feel free to drop me a line about the code or the blog in general! You can also contac

Custom markers...

    We have now seen numerous examples of markers and info-windows in Google Maps API v3. We will now see a last example where-in we will replace the customary marker icon with an icon of our choice! In the example that follows, I have shown 5 beaches in Goa along the Konkan coastal strip! These are nothing but markers, just with a different icon! Lets have a look at the following code!     The output of the above code looks as seen in the result section above. This is a simple code that goes here! If you have any queries or doubts or suggestions regarding this example you can comment on the same or feel free to drop me a mail ! In the meantime...Happy Mapping!

India's digital environmental atlas...

         The environment ministry has launched the first digital environmental atlas of India on the occasion of Earth Day. An interactive website of state of environment atlas of India depicts forest and biodiversity in green, water resources in blue and air pollution in brown colours.          The atlas provides flexibility and versatility for users to visualise environment spatial data using geographic information system (GIS) options. The atlas which is the first of its kind with regular updates has been developed by an NGO Development Alternatives (DA) with the support from the Environment Ministry.          The atlas is available on www.soeatlas.org and has features such as pressure-state-impact-response (PSIR) framework analysis, where all the maps are presented and displayed for the users' benefit.          With detailed database, the atlas is a treasure house for the environmentalists and researchers besides those keen to know about the state of envir

The dancing bubble...

         "Why does this bubble not dance?" asked my friend's 6 year old sister referring to a marker she was seeing on the map! So I decided the this marker needs to be animated! So, I developed the following code which shows a marker that bounces on its position and can also be dragged anywhere on the map!         The following is the code for the "dancing marker"... <html> <head> <title>Google Maps JavaScript API v3 - Bouncing marker</title> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script> <script type="text/javascript"> var marker; var map; function initialize() {     map = new google.maps.Map(document.getElementById("map"),     {         zoom: 5,               mapTypeId: google.maps.MapTypeId.ROADMAP,               center: new google.maps.LatLng(22.7964,79.5410)     });               marker = new google.maps.Mar

Retriving co-ordinates...

         We have seen 2 Google Maps API v3 examples wherein we have retrieved the latitude-longitude co-ordinates of the point of click on the map. In the first example we have displayed the co-ordinates in the information window and in the second , we have displayed the co-ordinates in a form in the information window.         Today we will create a code to retrieve the latitude longitude co-ordinates in a text box while simultaneously a marker appears on the map as well. So, here goes the code. <html> <head> <title> Google Maps API v3 - Adding marker on Click and retrieving the co-ordinates in a text box </title> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script> <script type="text/javascript"> var map;    //When using event as a parameter to a function declare map, strictly as a global variable function initialize() {     var myLatlng = new google.maps.L

Assessment of MGNREGA using GIS

            The Minister for Rural Development Shri Pradeep Jain “Aditya” informed the Rajya Sabhaon November 30, 2010 that It is proposed to use Geographical Information System (GIS) under Mahatma Gandhi National Rural Employment Guarantee Act (MGNREGA). In this regard, Ministry of Rural Development has set up an Expert Group to prepare a strategy for nationwide rollout and to evolve parameters for standardization with an objective to link GIS with grass root participatory planning and asset management and monitoring.             Replying to a written question the minister said use of GIS will strengthen decentralized participatory planning, implementation, capturing and monitoring of assets and evaluation of the works under MGNREGA and also this move will help the Ministry to bring in greater transparency and accountability in the implementation of the Scheme as real time data would be available.            This news clearly shows that India is slowly and steadily promo

Drive along - Cool coding

         This is something that will demonstrate to you the power of mapping! This is a Google Maps API v2 example, but just copy and paste the code in an html file and you will see something very cool! This will prove that mapping is real fun!          Let's have a look at the code first. Copy this code in your html file. Don't worry about the length of the code and the post in general. Just execute the code and you will surely enjoy what you see! <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"/> <title> Drive Along </title> <script src="http://maps.google.com/maps?file=api&amp;v=2&amp;sensor=false&amp;key=ABQIAAAAu3HXU_hLdVPTFGqLed_FCxT2yXp_ZAY8_ufC3CFXhHIE1NvwkxQbblEPYBGNoRsuuSU9aBfSq4VAZA" type="text/javascript"> </script> <script src="http://econym.org.uk/gmap/epoly.js" type="text/javascript"> </script>

GIS as a vocational elective from June 2011

            As 13 schools affiliated to the Central Board of Secondary Education (CBSE) across India are set to introduce a course on ‘geospatial practices’, a vocational elective for Std XI and XII from 2011, principals and teachers will be trained by an industry partner on ways to implement the programme, next month in Mumbai. The course will be expanded to other schools later.             Among the 13 schools, RN Podar School in Santa Cruz will be the first school in Mumbai that will introduce this course which focuses on various components of geographic information system/geospatial information systems (GIS) and remote sensing.             GIS is an emerging field and there is a lot of demand for candidates who are trained in GIS applications and technology today. It has a lot of relevance and so far no school has been providing education in this field. The subject is inter-disciplinary and covers various areas like geography, physics and mathematics, to name a few.

National Symposium on Remote Sensing and Geoinformatics in Infrastructure Development and Management

            With the focus of the nation shifting towards infrastructure development, through national programs like JNRUM, IRDP, and the participation of private players in infrastructure development, it is projected that annual investments to the tune of Rs. 1,000 Billion will be made in the country across the next 5-7 years. The efficacy of Geoinformatics and Remote Sensing in Infrastructure planning, development and management is well recognized and promoted by the Department of Space and other governmental agencies. In this context, the National Symposium and ISRS Annual Convention is organized on the topic "GIS AND REMOTE SENSING IN INFRASTRUCTURE DEVELOPMENT" from the 29th of November, 2010 to 4th December, 2010.            The Symposium will expose the frontline developments in remote sensing and Geoinformatics to the infrastructural developers, enabling the latter to appreciate the cost-saving and accuracy enabled by the technology. It is expected that

What is GPS?

            Having seen what GIS is, we will now have a look at what GPS or the Global Positioning System is! Wikipedia's following GPS definition says it all. "The Global Positioning System (GPS) is a space-based global navigation satellite system (GNSS) that provides reliable location and time information in all weather and at all times and anywhere on or near the Earth when and where there is an unobstructed line of sight to four or more GPS satellites."            The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. The 24 satellites are orbiting the earth about 12,000 miles above us. They are constantly moving, making two complete orbits in less than 24 hours. These satellites are travelling at speeds of roughly 7,000 miles an hour.           GPS satellites are powered b

Fedora Geo Spin

         It's here! An GIS oriented Operating System!...Currently under development with a target release as Fedora 15, Fedora Geo Spin is a collection of mapping tools that run on Fedora. This includes tools for map making, integration into OpenStreetMap, and components that can be run on a GPS enabled device.          This spin will include map making tools that integrate with OpenStreetMap. This will enable map makers to use Fedora as a platform for cartography.The end goal is an ISO and kickstart that can be depolyed to work with most cartography setups.          Integration with developer tools for developing other programs that work with GPS devices. This may lead to a developer subspin that integrates development libraries and tools including for GPS devices. This probably includes a group in comps for handling Geo related libraries and the development counterparts.          This Geo spin can be integrated with MIDs and other devices that can be enabled with a GPS,

What is GIS?

          Once I started writing this blog, I received a number of feedbacks from readers asking me to write something about what exactly GIS is. So here is some information, that will give you an idea about " What is GIS? "           A geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information. GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts.             A GIS helps you answer questions and solve problems by looking at your data in a way that is quickly understood and easily shared. GIS technology can be integrated into any enterprise information system framework.           People use GIS to map locate where things are and let you find places that have the feature that you are looking for, and to see where

Tripura to use satellites to track terrorrists

          Tripura will soon use satellites to track terrorists in the state, director general of police K. Saleem Ali said on Sunday the 14th of November, 2010 adding that the state's three-decade old militancy will be "flushed out within the next few months". Tripura would be the third state in India, after Jammu and Kashmir and Jharkhand, to introduce the Geo Satellite Imagery Systems (GSIS) for curbing militancy.           The satellite image would be as clear as if taken from 10 feet above the ground. All district police chiefs would operate this new system to locate the activities of the separatist outfits. All the police stations of the state are being connected electronically for better coordination. In the first phase 22 out of the 66 police stations would be linked!           A new method to register a FIR through SMS will also be introduced and would commence from January next year with the help of the National Informatic Center. Source: Hindustan Tim

Form info window

         Today we will look at a Google Maps API v3 example to add a form in the information bubble! This is usually required when we wish to accept some data/information from the user! This data can be saved to a server in the form of an XML file or a database! The information can then be retrieved back at a later stage, when necessary!          In this example we will only look at form in the information bubble! The connectivity part with the server will be discussed in another post! So, today's code snippet is as seen below! <html> <head> <title> Google Maps API v3 - Adding marker and info window on Click and creating a form in the infowindow with the lat-lng information in it. </title> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script> <script type="text/javascript"> var map;    //When using event as a parameter to a function declare map, strictly as a

Static Info window only...

           In our last Google Maps API v3 example we saw how info windows appeared on user click. We saw why such a thing is necessary and the benefits of that! Today we will look at a very simple example, where in we will place a single marker on the map! Something like a simple marker example in this post!           Our today's code is below! <html> <head> <title> Google Maps API v3 - Simple info window only example </title> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"> </script> <script type="text/javascript"> var map; function click_window() {              map = new google.maps.Map(document.getElementById("map"),              {                               zoom: 5,                               center: new google.maps.LatLng(22.7964,79.5410),                               mapTypeId: google.maps.MapTypeID.ROADMAP              });      

Jugnu: India's first Nano Satellite

          IIT-Kanpur with its nano satellite 'Jugnu' has set new highs in the field of space research. A team of students, working under Dr NS Vyas (the visionary man behind the making of the nano-satellite) and other faculty members of the institute, have successfully made the country's first nano-satellite to be developed for the first time by any educational institute.           The development of the Jugnu started in the year 2008 with a team of 3 students. With time, the team has grown to the size of more than 50 students ranging from 1st year undergraduates to final year postgraduates and 14 professors from different disciplines to complete this challenging mission.            The satellite has been handed over to two ISRO scientists, DVA Raghav Murthy (Project Director, Small Satellite Projects) and Dr SK Shiv Kumar (Director, ISRO satellite tracking centre), by President Pratibha Patil on March 6, 2010. View the pictures of the ceremony at IIT Kanpur's p

Playing with the markers and info window bubbles...

    In the last few posts, we have seen some marker examples and some information window examples. Now, lets do something interesting combining these two things. Just writing that "This is an info window" in the information bubble is not very interesting! And I know this...Have gone through the same phase!     So, today we will do something interesting! We will display the latitude- longitude co-ordinates of the point that the user clicks on the map! Doing this is not at all complex! Copy paste the following code and you will see for yourself a map coming to life!     The output of the above code looks as seen in the result section above! If you have any queries regarding the above code please comment on the blog post or feel free to contact me at my mail ID .

Only information bubbles...

         After displaying markers and markers with info windows, we will now display only info windows on the map. So our aim becomes, placing an info window on a google map when a user clicks on the map.          Now, the first question that will pop up in your mind is why do we need such a thing? To answer this question let us consider a simple example. Consider that, when an user clicks on a map, a marker appears with an info window and you want the user to enter some data in a form in the info window and save that data. Now, if the user enters inconsistent data, there would be marker on the map, having no valid information! The marker would then be rendered useless, with no information! Something like a dangling pointer!           Now, if you haven't understood a word of this; don't worry. You will soon understand the importance of this example! So, without any further discussions, let's have a look at the code!           Here goes the code... <html> <

Code for fun..!

         Just wrote a small 3 lines shell script which is capable of searching any random place on Google Map. Try it on your linux boxes! For those who prefer windows, I am sorry to say that this code will not run on your machines. I work on linux system and so I am using some linux specific commands in the script!          So here goes the shell script! while [ $? == 0 ] do     zenity --info --text="Do not use spaces between multiple words. Instead use the + sign. For example 'new+delhi and not new delhi'"     search=`zenity --title "Google Maps Location Search" --entry --text "Search: "`     if [ $search ==  ]     then         zenity --question --text="Do you wish to search another location?"     else         firefox http://maps.google.com/maps?q=$search         zenity --question --text="Do you wish to search another location?"     fi done         See the results for yourself! It's simple and easy

A marker with an information window

         Following the sequence, I should be discussing a marker based example! Markers loading from an XML file. But, we will disrupt the sequence for the sole reason that I don't want to discuss comparatively tough examples as of now! So, we will jump on to a simple example to display an information window or the info window bubble as it is popularly known; along with a marker!          Let's have a look at the following code. This is a simple code which will place a marker at "India" with an information window attached to it which appears only when the marker is clicked! The code goes as below: <html> <head> <title> Google Maps JavaScript API v3 Example: Simple  Infowindow </title> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"> </script> <script type="text/javascript"> function initialize() {     var myLatlng = new google.maps.LatLng(22.7964,

GIS India News Titbits

         Treading on the foot steps of Gujarat for improvement in governance, the Himachal Pradesh government on Wednesday, 10th November 2010, announced to set up geo-informatics centre for planning with help of the latest digital techniques under supervision of department of science, technology and environment.          Chief Minister Prem Kumar Dhumal said the centre would be set up on the lines of Bhaskaracharya Institute of Space Applications and Geo-Informatics (BIGSAC), Gandhinagar, Gujarat, and would be named as Aryabhatta Geo-Informatics and Space Applications Centre (AGiSAC).          Departments that are directly linked with common man including Revenue, Forest, Education, Health, Agriculture, Horticulture, Panchayati Raj and Rural Development would be the first ones to be taken up for planning under the project by digitisation of their record. This would make the working transparent and by making information available to the people on internet.             S

Multiple markers...

            It rarely happens that there is just one point of interest or just one location that you would like to mark! Generally there is a bunch of markers that appear on the map! Specifically, you want a list of latitude and longitude pairs representing the points of the markers you'll plot.             To store the list of points, you can combine the power of Javascript's array and object constructs. An array stores a list of numbered entities. To access the elements of the array, you must use their numeric indices. So array[0] will point to the first element in the array while array[n] will point to the nth element in the array.             I will use the following piece of Javascript code to demonstrate how multiple markers can be made to appear on a map using the array structure and the for loop for iteration.             Nothing here should be much of a surprise! You can see that the google.maps.Marker function is called for each of the markers, so you can

Celabrate GIS Day!

                   The countdown has begun...Only 4 days to go! On the 17th of November, 2010, the world will celebrate "GIS Day". GIS day is held each year in the third week of November, on the Wednesday during the Geography Awareness Week, a geographic literacy initiative sponsored by the National Geographic Society.                   GIS Day is playing a powerful role in creating geographic awareness throughout our world. GIS Day provides an international forum for users of geographic information systems (GIS) technology to demonstrate real-world applications that are making a difference in our society.          More than 80 countries will participate in holding local events such as corporate open houses, hands-on workshops, community expos, school assemblies, and more. Any organisation that uses GIS can participate in this global event.          Large or small, there are many ways you can participate. From showing a few co-workers what GIS does for your organi

A simple marker example

            Once you have set up your map as seen in the earlier post you can now place a marker at your point of interest on the map. A marker is a symbol that is used to point something interesting or important on the map! A marker can be overlayed on a map statically, dynamically i.e. when a user clicks on a map, a marker appears on the map. Markers can also be loaded from an XML file, a plain text file and also a CSV file. We will be seeing an example of each in the subsequent posts.             Later on we will also see how to add an information window to the markers on the map! But that will be at a later stage. Let us have a look at the following code first which will add a marker at the Rajya Sabha, New Delhi.            And here you are...You have placed a marker at your point of interest. The output will look as seen in the result section above. Feel free to change the point of interest and see a marker at a location of your choice. Happy mapping!

Geocaching - The world's largest treasure hunting game!

         Geocaching is a high-tech treasure hunting game played throughout the world by adventure seekers equipped with GPS devices. The basic idea is to locate hidden containers, called geocaches, outdoors and then share your experiences online. Geocaching is enjoyed by people from all age groups, with a strong sense of community and support for the environment. The following video has been taken from "Geocaching - The official global GPS Cache Hunt Site". This site will give you a brief idea of what Geocaching exactly is!           On May 2, 2000, at approximately midnight, eastern savings time, the great blue switch* controlling selective availability was pressed. Twenty-four satellites around the globe processed their new orders, and instantly the accuracy of GPS technology improved tenfold. Tens of thousands of GPS receivers around the world had an instant upgrade.            The announcement a day before came as a welcome surprise to everyone who worked wit