Guides & Tutorials

[ftvfatboy]

Active Connections

Proto Local Address Foreign Address State
TCP macintosh: 27374 modem-123.tun.dialup.co.uk: 50505 ESTABLISHED
TCP macintosh: 80 proxy.webcache.eng.sq: 30101 TIME_WAIT
TCP macintosh MACINTOSH: 0 LISTENING
TCP macintosh MACINTOSH: 0 LISTENING
TCP macintosh MACINTOSH: 0 LISTENING


Now, straight away, this should make more sense to you. Your computer is connected on two ports, 80 and 27374. Port 80 is used for http/www transmissions (ie for all intents and purposes, its how you connect to the net, although of course it's a lot more complicated than that). Port 27374, however, is distinctly suspicious; first of all, it is in the registered port range, and although other services (like MSN) use these, let's assume that you have nothing at all running like instant messengers, webpages etc....you're simply connected to the net through proxy. So, now this connection is looking even more troublesome, and when you realise that 27374 is a common port for Netbus (a potentially destructive Trojan), you can see that something is untoward here. So, what you would do is:


1) run Netstat , and use:

Netstat -a

then

Netstat -an

So you have both Hostnames AND IP addresses.


## Tracerouting ##

Having the attacker's IP is all well and good, but what can you do with it? The answer is, a lot more! It's not enough to have the address, you also need to know where the attacker's connections are coming from. You may have used automated tracerouting tools before, but do you jknow how they work?

Go back to MSDOS and type


tracert *type IP address/Hostname here*


Now, what happens is, the Traceroute will show you all the computers inbetween you and the target machine, including blockages, firewalls etc. More often than not, the hostname address listed before the final one will belong to the Hacker's ISP Company. It'll either say who the ISP is somewhere in there, or else you run a second trace on the new IP/hostname address to see who the ISP Company in question is. If the Hostname that you get back doesn't actually seem to mention an actual geographical location within its text, you may think all is lost. But fear not! Suppose you get a hostname such as

http://www.haha.com

Well, that tells us nothing, right? Wrong....simply enter the hostname in your browser, and though many times you will get nothing back, sometimes it will resolve to an ISP, and from there you can easily find out its location and in what areas they operate. This at least gives you a firm geographical location to carry out your investigations in.

If you STILL have nothing, as a last resort you COULD try connecting to your target's ISP's port 13 by Telnet, which will tell you how many hours ahead or behind this ISP is of GMT, thus giving you a geographical trace based on the time mentioned (although bear in mind, the ISP may be doing something stupid like not having their clocks set correctly, giving you a misleading trace. Similarly, a common tactic of Hackers is to deliberately have their computer's clock set to a totally wrong time, so as to throw you off the scent). Also, unless you know what you're doing, I wouldn't advise using Telnet (which is outside the parameters of this tutorial).

## Reverse DNS Query ##

This is probably the most effective way of running a trace on somebody. If ever you're in a chatroom and you see someone saying that they've "hacked into a satellite orbiting the Earth, and are taking pictures of your house right now", ignore them because that's just bad movie nonsense. THIS method is the way to go, with regard to finding out what country (even maybe what State/City etc) someone resides, although it's actually almost impossible to find an EXACT geographical location without actually breaking into your ISP's Head Office and running off with the safe.

To run an rDNS query, simply go back to MS-DOS and type

netstat

and hit return. Any active connections will resolve to hostnames rather than a numerical format.

# DNS

DNS stands for Domain Name Server. These are machines connected to the Internet whose job it is to keep track of the IP Addresses and Domain Names of other machines. When called upon, they take the ASCII Domain Name and convert it to the relevant numeric IP Address. A DNS search translates a hostname into an IP address....which is why we can enter "www.Hotmail.com" and get the website to come up, instead of having to actually remember Hotmail's IP address and enter that instead. Well, Reverse DNS, of course, translates the IP Address into a Hostname (ie - in letters and words instead of numbers, because sometimes the Hacker will employ various methods to stop Netstat from picking up a correct Hostname).

So, for example,

298.12.87.32 is NOT a Hostname.
mail6.bol.net.au IS a Hostname.

Anyway, see the section at the end? (au) means the target lives in Australia. Most (if not all) hostnames end in a specific Country Code, thus narrowing down your search even further. If you know your target's Email Address (ie they foolishly sent you a hate mail, but were silly enough to use a valid email address) but nothing else, then you can use the Country codes to deduce where they're from as well. You can also deduce the IP address of the sender by looking at the emails header (a "hidden" line of code which contains information on the sender)...on Hotmail for example, go to Preferences, and select the "Full Header's Visible" option. Alternatively, you can run a "Finger" Trace on the email address, at:

www.samspade.org

Plus, some ISP's include their name in your Email Address with them too (ie Wanadoo, Supanet etc), and your Hacker may be using an email account that's been provided by a Website hosting company, meaning this would probably have the website host's name in the email address (ie Webspawners). So, you could use the information gleaned to maybe even hunt down their website (then you could run a website check as mentioned previously) or report abuse of that Website Provider's Email account (and thus, the Website that it goes with) to

abuse@companynamegoeshere.com

If your Hacker happens to reside in the USA, go to:

www.usps.gov/ncsc/lookups/abbr_state.txt

for a complete list of US State abbreviatons.

[ftvfatboy]

## List of Ports commonly used by Trojans ##

Please note that this isn't a complete list by any means, but it will give you an idea of what to look out for in Netstat. Be aware that some of the lower Ports may well be running valid services.

UDP: 1349 Back Ofrice DLL
31337 BackOfrice 1.20
31338 DeepBO
54321 BackOfrice 2000


TCP: 21 Blade Runner, Doly Trojan, Fore, Invisible FTP, WebEx, WinCrash
23 Tiny Telnet Server
25 Antigen, Email Password Sender, Haebu Coceda, Shtrilitz Stealth, Terminator, WinPC, WinSpy, Kuang2 0.17A-0.30
31 Hackers Paradise
80 Executor
456 Hackers Paradise
555 Ini-Killer, Phase Zero, Stealth Spy
666 Satanz Backdoor
1001 Silencer, WebEx
1011 Doly Trojan
1170 Psyber Stream Server, Voice
1234 Ultors Trojan
1243 SubSeven 1.0 - 1.8
1245 VooDoo Doll
1492 FTP99CMP
1600 Shivka-Burka
1807 SpySender
1981 Shockrave
1999 BackDoor 1.00-1.03
2001 Trojan Cow
2023 Ripper
2115 Bugs
2140 Deep Throat, The Invasor
2801 Phineas Phucker
3024 WinCrash
3129 Masters Paradise
3150 Deep Throat, The Invasor
3700 Portal of Doom
4092 WinCrash
4567 File Nail 1
4590 ICQTrojan
5000 Bubbel
5000 Sockets de Troie
5001 Sockets de Troie
5321 Firehotcker
5400 Blade Runner 0.80 Alpha
5401 Blade Runner 0.80 Alpha
5402 Blade Runner 0.80 Alpha
5400 Blade Runner
5401 Blade Runner
5402 Blade Runner
5569 Robo-Hack
5742 WinCrash
6670 DeepThroat
6771 DeepThroat
6969 GateCrasher, Priority
7000 Remote Grab
7300 NetMonitor
7301 NetMonitor
7306 NetMonitor
7307 NetMonitor
7308 NetMonitor
7789 ICKiller
8787 BackOfrice 2000
9872 Portal of Doom
9873 Portal of Doom
9874 Portal of Doom
9875 Portal of Doom
9989 iNi-Killer
10067 Portal of Doom
10167 Portal of Doom
10607 Coma 1.0.9
11000 Senna Spy
11223 Progenic trojan
12223 Hack´99 KeyLogger
12345 GabanBus, NetBus
12346 GabanBus, NetBus
12361 Whack-a-mole
12362 Whack-a-mole
16969 Priority
20001 Millennium
20034 NetBus 2.0, Beta-NetBus 2.01
21544 GirlFriend 1.0, Beta-1.35
22222 Prosiak
23456 Evil FTP, Ugly FTP
26274 Delta
30100 NetSphere 1.27a
30101 NetSphere 1.27a
30102 NetSphere 1.27a
31337 Back Orifice
31338 Back Orifice, DeepBO
31339 NetSpy DK
31666 BOWhack
33333 Prosiak
34324 BigGluck, TN
40412 The Spy
40421 Masters Paradise
40422 Masters Paradise
40423 Masters Paradise
40426 Masters Paradise
47262 Delta
50505 Sockets de Troie
50766 Fore
53001 Remote Windows Shutdown
54321 SchoolBus .69-1.11
61466 Telecommando
65000 Devil


## Summary ##

The Internet is by no means as anonymous as some people think it is, and although this is to the detriment of people's security online, this also works both ways....it IS possible to find and stop even the most determined of attackers, you just have to be patient and keep hunting for clues which will help you put an end to their exploits.

[ftvfatboy]

How to remove Hijacker

--------------------------------------------------------------------------------

A Hijacker is any software that resets your browser's settings to point to other sites. Hijacks may reroute your info and address requests through an unseen site, capturing that info. In such hijacks, your browser may behave normally, but be slower. Search Hijackers change your search settings. Homepage Hijackers will change your home page to some other site. Error Hijackers will display a new error page when a requested URL is not found. Hijacking has become very common, as these guide illustrate. This guide explains how to clear such hijacks of Microsoft Internet Explorer (IE) manually and how to prevent it by disabling scripting.

Search Hijacks
If your Search capability has been hijacked, your use of IE's Search Button (see below) will lead to unexpected (and usually unwanted) results.
What the hijacker has done is to change four registry keys:

[ftvfatboy]

If your Home page changes unexpectedly, you have a "HomePage hijack", and will see this page each time you invoke your browser. What the hijacker has done is to change the registry key:
* In the Root key HKEY_CURRENT_USER, the key Software\Microsoft\Internet Explorer\Main has a value "Start Page" that has likely been reset to something.
* In the Root key HKEY_LOCAL_MACHINE, the key Software\Microsoft\Internet Explorer\Main has a value "Start Page" that has likely been reset to something like http://yourbookmarks.ws/

[ftvfatboy]

IE supports "scripting", a useful but dangerous capability that you will want to disable if you ever visit unknown sites. The scripts that can be run will be Javascript or VBScript, often embedded in a web page you visit. Such scripts can execute ActiveX controls, which can do anything in your machine that any software can do.

To be stop scripting the easy way, do this: From IE's top menu bar, select the Tools menu. On this menu, choose "Internet Options". It will display a popup dialog box. Click on the Security tab, to see a display like that to the right.

Each zone has four security levels available, ranging from Low Security to High. IE is configured for Low Security when it is first installed. Medium or High is what you need.

[ftvfatboy]

Problem:

Computer freezes or reboots at random intervals.


Possible fixes:

Update Windows. Ensure you have the latest service packs installed.

Update all Device drivers. Driver issues, especially for video drivers, are a common cause of system crashes.
Scan for viruses, malware, spyware. Click here for a complete list of free utilities that will perform a thorough scan of your system.

Re-seat all cards & plugs.

Test your RAM. Use this utility, and let it run overnight for best results.

Test your HDD. Click Start --> My Computer. Right-click the disk you want to check (usually C: ). Select Properties. Click on the Tools tab. Under Error Checking, click Check Now. Select the Automatically Fix File System Errors option, and the Scan For and Attempt Recovery of Bad Sectors option. Click on Start.

Defragment your hard drive(s). Click Start --> All Programs --> Accessories --> System Tools --> Disk Defragmenter.

Confirm that system temperatures are not reaching critical levels. Processors are especially susceptible to overheating, but other components can also cause problems.Consult the forums for diagnostic tools that will analyze your system temperatures.


Ensure your power supply is adequate to the needs of your system. If you have purchased a bare bones system to save a few bucks, and have added components over time (drives, video cards, etc.), these add-ons may be making demands that your power supply is unable to handle. Determine the wattage rating on the power supply in your machine; the label on it will usually provide this information. Then click on this link to calculate your system's requirements.


Try to recall any changes you have made to your system. New hardware or software will sometimes cause conflicts, creating problems where none previously existed. If you begin having issues and can pinpoint their occurrences to a time immediately after a change was made to your system, the new hardware/software may be the problem.

Clean the registry. A Google search will direct you to several free utilities that will scan and clean your registry.

[ftvfatboy]

Windows XP Professional includes a basic PC remote control tool which lets you log onto your PC remotely from anywhere. Do you know how to use it


It’s called Remote Desktop Connection, and when you’ve properly configured your PC, this handy utility will let you log into your computer from anywhere in the world and control it as if you were sitting in front of it instead of half a world away.

If you’re running Windows XP Professional, you already have all the software you need to connect remotely to your PC. Whether you’d like to monitor a server, grab files from your home PC at work, or just keep an eye on your machines when you’re out, connecting remotely is easy to do. However, due to the vagaries of network configurations and various other quirks beyond your control, you may not be able to actually connect. Until now.



Prepping your system

First, you need to know the IP address of the computer you want to connect to. The only sure-fire way to always be able to connect to your PC’s is to use an ISP that provides you with a static IP address. Most ISPs give customers dynamic IP addresses, which can change every few days or even hours. Because your IP address is the way you’ll locate your computer on the net, you’ll need to know what your IP address is and monitor it as it changes.

The good news is that there are loads of programs that will notify you of IP address changes, whenever they occur. We like IP Address Monster (www.ipmonster.com). It’s a small program that runs in your system tray and can be configured to e-mail you whenever your IP address changes.




IP Address Monster should be your first stop to remote connectivity. This handy utility will keep tabs on your Internet address and send you an e-mail whenever it changes.



Now that you know your IP address, you need to make sure that Remote Desktop Connection is enabled. Make sure your firewall is configured to allow incoming connections on port 3389 (firewalls vary, so check your documentation to find out how to open the port).

You can turn on Remote Desktop Connection in the System Control Panel (Start, Control Panel, System). Check the Remote tab and make sure “Allow users to connect remotely to this computer” is checked. You’ll also need to have at least one user account that requires a password because accounts without passwords are prohibited from logging into Remote Desktop.





To enabling Remote Desktop, open the System Control Panel, go to the Remote tab, and check this box.



It’s important to make sure the passwords on the machine you’re going to remotely log into are “good” ones. This means you should use a mixture of letters and numbers, avoid words that are found in dictionaries, and change the password regularly to protect yourself from mischief.



Making the connection

At this point, your PC should be prepped and patiently waiting for a connection. To log in, you need to open the Remote Desktop Connection client on your remote PC. Go to Start, Programs, Accessories, Communications, Remote Desktop Connection. Input the IP address you want to connect to (courtesy of IP Address Monster) in the Computer field. Then enter your username and password.

Now you’ll want to tweak a few settings to optimize your remote experience. Whiz-bang features gobble up bandwidth, so you should tune your settings to match your home net connection. We recommend you start with a minimal feature set. Press the Options button, then the Display tab. Change the display settings to full-screen, 256-color. This looks acceptable and consumes practically no bandwidth. You’ll also want to browse to the Experience tab and change the Performance setting to reflect your home PC’s connection speed.




Switching to a lower color resolution and a smaller display area will greatly minimize the amount of data that has to transfer between your computer and the remote PC.



Once you’ve tuned the connection a bit, you’re ready to connect. Press the Connect key and you’re in!



What to do next

At this point, you should be connected. You can run programs and manipulate files just like you’re sitting in front of your PC. In fact, you can even use your PC’s e-mail and web browsers. Do you want to start downloading Desert Combat now so you can start playing it when you get home That’s easy enough; just log into your PC using Remote Desktop, open your web browser, and download the file. It will be sitting on your machine waiting for you as soon as you get home. If all your PCs are running Windows XP Pro, and you enable drive-sharing in the Local Resources tab, you can transfer files from remote PC to local PC. You can even remotely transfer files between local PCs on your home network.


Once connected, you can interact with printer ports and networked hard drives. This is a handy way to delete those “special interest” videos you downloaded before your wife finds them.

[ftvfatboy]

Google Earth: Planetary Phenomenon

From its exit in August 2005, Google Earth became a true phenomenon. The receipt of its success? A brilliant concept (even if it is not new as we will see it) and an impeccable technical realization. The goal of the software? To provide an urban and geographical guide total, based on a representation 3d detailed and realistic of the Earth. In theory, Google Earth makes it possible to seek imports what on our beautiful planet: a pizzeria, a historic building, a route of its hotel to the cinema nearest. The software posts a level of detail such as one can even have access to a modeling 3d (simple) of the buildings over the detailed satellite images, themselves and taking account of the relief. Sum colossal of information is diffused in "streaming" since Internet (even if the images satellite can go back to a few years), in short, Google Earth is a mine of information on our planet, constantly updated.

In practice, unfortunately, all that relates to currently only the United States: the buildings are reserved for 38 cities American and only some European cities have a level of high detail and information practical. Would Google Earth be thus a simple gadget with the interest limited for the remainder of planet? Certainly not! The force of the software is indeed to make it possible to the Net surfers to add their own information. Simple "bug" on the sphere with modeling 3d of a monument or a building, it is thus possible to personalize Google Earth with its own way and to benefit from innumerable information brought by a very active community.




Earth with range of mouse: To discover Google Earth

Let us start with the beginning, namely the remote loading of the software. Google Earth exists in several versions. The paying versions propose additional functionalities like the possibility of adding buildings in 3d or functions related to the GPS, but the free version is obviously sufficient to explore the Earth under all its seams. Google Earth is available under Windows and Mac OS X (10.3 minimum)

Before launching us to the research of the villa of Zidane or desert of Tatooine, we with the interface of the software, broken up into three parts familiarize already:

The principal window.
The panel of navigation.
The side panel.

Navigation in Google Earth can be made several manners. Most intuitive is "to handle" the ground with the mouse, a method which uses all the buttons.

The left button enables you "to catch" the terrestrial sphere and to turn it in all the directions.
The right button allows zoomer ahead or behind, but it is much more practical to carry out this handling with the serrated roller of the mouse which lends itself to it to wonder.
Lastly, the central button makes it possible to modify the slope and to swivel of left on the right.



Short cuts keyboard are also available:
+ and - for zoomer ahead and behind.
Pg Up and Pg Down to modify the slope.

Lastly, you can use the panel of navigation which gathers the same functions:

Central paving stone to turn around the sphere.
The buttons left and right-hand side to carry out a rotation on the left or on the right.
The small rule of left for zoomer ahead and behind.
The small rule of right-hand side to modify the slope.



Let us note then the presence of three buttons in bottom on the right of the interface to print a sight, to send it by electronic mail, or to add information in the form of a simple marker, a superimposed image or a modeling in 3d (this last option being reserved for Google Earth Plus, paying). We will reconsider this function later.

[ftvfatboy]

The side panel, multi-fonction pocket knife of the "Google-earthien"

These possibilities of navigations already make it possible to have fun with the sphere and of zoomer on more detailed places (of the zones generally delimited by squares of color chestnut) to be filled with wonder at the level of precision of certain agglomerations. If you live Paris, Marseilles, Lyon, Strasbourg or Bordeaux, you will not have undoubtedly evil to find your house.



Nevertheless, the essence of Google Earth is in the side panel. That Ci is divided into three parts.

The module of research

This one comprises three mitres "Fly to" makes it possible "to fly" towards a specific place by seizing the name. It goes without saying that during the first minutes of use of the software, it is one of the jouissives functionalities: what a pleasure "of leaping" from Paris in New York, Rio or Peking in a few seconds! "Local Search", as its name indicates it, consists in seeking a trade or a monument in a city. Lastly, "Directions" makes it possible to calculate a route between two points. The last two mitres are more or less reserved for the American public.

The module "Places"

This module is the equivalent of the bookmarks in a navigator. You can safeguard your places preferred there to reach it later on of a simple double clic. It is also in this panel that the places added with the files added by the users are stored.

To exploit this module, one uses the button of the panel of navigation. A clic on this button opens a menu proposing to you to add a marker ("placemark"). You can also add other types of information as more precise charts which are superimposed on those provided by defect, or even of the models 3d of buildings or monuments, but this requires jurisdiction which exceed this article. We will however see some very successful examples of these additions.

To add a "placemark" is as simple as to add a bookmark to your navigator. You can use the button bug and choose "placemark", use the short cut Ctrl+N keyboard or, in the panel "Places", carry out a clic right and choose New > Placemark. A dialog box opens, in which you can name your marker, to assign another icon to him or to place it in an existing file (or to create new).

Note the buttons of reading in bottom of the module. Those enable you to carry out a turn of the world of your markers. To give an account of their interest to you, launch the turn of the places available by defect: campus of Google to the Imperial Palate of Tokyo while passing by Berlin or Peking, there is what to return jealous Jules Verne!

The module "Layers"

It makes it possible to post or mask a great number of copies on the sphere (borders, reliefs, buildings in 3d, roads, trade, schools, churches...) by notching them. The principal copies (real, reliefs, roads, lodging, restoration, borders) are also accessible since the panel from navigation.

This system of check box also functions in the panel "Places", from where interest to create files sets of themes where to arrange your favorite places. By notching or stripping the file, you will be able thus to post or hide all the markers who are there.




A software in perpetual motion

Several types of information can be added to Google Earth. These additions can be simple markers posed on an existing place (a subway station, a monument, a building...), but also the superposition of an image over the information provided by defect, like a more precise air sight of a city. For most senior, it is also possible to add models in 3d of monuments or buildings. The addition of information and in particular of modelings or charts is a relatively complex subject which exceeds the framework of this article. We nevertheless will teach you how to benefit from this richness from information.

As we saw previously, it is possible to define markers in precise places. It is also possible to safeguard these markers in the shape of a file KMZ which could be carried out by any user of the software, the place being then automatically added to the panel "Places".

The Community Google Earth
The first level of personalization is provided by the community Google Earth. The software indeed places at the disposal a forum where find impassioned virtual sphere.


The places added by the members of the community are classified and integrated every month into Google Earth. You can reach it by notching Google Earth community in the panel "Layers". By unfolding small Google Earth Community, you will notice that the places themselves are classified in various categories: travel information, transportation, nature & geography...

An example? Turn over on our good France old woman and zoomez on Paris. You ensure that the category Google Earth Community is stripped and unfold it. Now, notch "Transportation": the subway stations of the capital appear. Strip this option and notch "Education now" and you will see appearing the Sorbonne and Sciences Po.



The other information, considered to be less interesting by the community, is stored in the subcategory "Unranked". You can nevertheless find there information rather amusing. Always on Paris, a Net surfer indicated several places where a short film of Claude Lelouch was turned, another famous Café of the Two Mills of Amélie Poulain. Let us benefit from this example to use another functionality of the software: its integrated navigator. When you click on a marker, this one posts a bubble of information which can contain a bond towards the subject of the Community forum or an external site bringing more information, for example on a monument. A panel emerges then, allowing you of surfer on this site inside even of Google Earth. The software exploits engine Internet then To explore.

[ftvfatboy]

A little tourism

We saw it, Google Earth allows to post modelings 3d of buildings over the satellite charts. Nevertheless, this functionality relates to currently only 38 American cities. Fortunately, of many buildings 3d, created by the users with third software like SketchUp (repurchased since by Google), can be downloaded on many blogs. Here a selection of modelled monuments. To visualize them, ensure you to have notched the category "Buildings" in the panel "Layers" or the panel of navigation.

The Eiffel Tower

Paris has a sight relatively detailed in Google Earth, but the Eiffel tower seems to have been crushed on the ground. This file gives again all its splendour to him, at the point to even put at knees the most modest configurations.



Colisee


Vestige emblematic of the Roman Empire, Colisée of Rome east reproduces in a rather faithful way with this model.



Hollywood

The famous letters of the hill of Hollywood overhang Los Angeles. Have fun with the camera, the vertiginous sight on the town of Los Angeles is impressive.



The guide of the celebrities

The "people" are with the honor on Google Earth. Human curiosity being what it is, temptation to fly over the properties of the stars of Hollywood or the personalities of this world is large. Among the multitude of markers available on the site Sauce Ketchup , we can thus steal such Tom Thumb of the villa of Zinédine Zidane to Madrid to the property of Bill Gates to Seattle while passing by the house of impossible to circumvent Tom Cruise... Unless you did not prefer David Hasseloff (the drafting declines any responsibility on the use of these bonds). These files are simple markers, you will not be able to thus visualize the properties under all their seams.






One finds some places of turning (even of pilgrimage for the fans): the desert of Tatooine, in the first Wars Star, was turned to Tunisia, but also to Arizona, at the place of this marker.



Peter Jackson put a point of honor to turn the entirety of the Lord of the Rings in his native New Zealand. Many places of turning, the volcano used to represent the Mountain of the Destiny, where Frodon must throw the single ring, is undoubtedly one of most impressive.



Lastly, magic of Google Earth and the cinema (sic), we finish this turn of the world express train by the gendarmerie of Saint-Tropez, to return visit in Cruchot, Gerber and the others. Is that worth the Earth of the Medium well, not?

[ftvfatboy]

NASA World Wind: Another manner of scanning the Earth

Google Earth, even if its quality is undeniable, is not the only free virtual terrestrial sphere. Its "competitor" is called NASA World Wind and even if it shows a light delay on certain points vis-a-vis Google Earth, it is far from being uninteresting and has some specific qualities, in particular a more scientific approach. On the other hand, contrary to Google Earth, NASA Worldwind does not have vocation to be a total urban guide allowing to find its way or the pizzeria nearest. Contrary to Google Earth, it is of more available only for Windows.



The interface of NASA World Wind is rather different from that of Google Earth: one does not find panels multiple, but a bar of icons in top of the window. It gives access quickly the posting (or not) of the multiple layers of information suggested by the software: satellite images, charts topographic, meridian, borders, flags of the countries or monuments.



As for Google Earth, the most detailed information and sights relate to only the United States, in particular the sight USGS Urban Area which provides very precise representations of the urban zones (but in black and white and without building in 3d contrary with Google Earth). Returned relief is comparable so that Google Earth proposes. The management of the relief is effective for the mountains, but NASA World Wind has the annoying tendency to plate an artificial relief on the cities, which causes somewhat hazardous results.

Europe is even more badly parcelled out in World Wind and it is useless to seek there such precise sights of large French cities. Even Paris is much less detailed there.

The volcano of theSaint-Helene Mount with NASA World Wind



The volcano of theSaint-Helene Mount with Google Earth



Which is then the interest of NASA World Wind compared to Google Earth, more especially as it is definitely bulkier? The answer lies in the excellent module Scientific Visualisation Studio.

This module, accessible since a pressure on the F1 key, gives access to you many animations which are superimposed on the surface of the sphere. Those Ci describe scientific phenomena classified by categories: climatic changes, natural disasters, evolution of the vegetation... Each animation is accompanied by a description (in English) of the phenomenon. Google Earth, through the many files made available by the community, also proposes a certain number of animations of this type, but they are not centralized in a module of the software, which concentrates rather on practical information.

Another interesting possibility of NASA World Wind, in addition to the Earth, the software also proposes a visualization 3d of the Moon. Google proposes these charts in the form of service Web, but not of three-dimensional version.

With final, the two software is relatively complementary. NASA World Wind is ended a little less graphically and does not have the dynamic community of Google Earth, but it remains a very good tool.

Services Web: Earth since its navigator

Google Earth or NASA World Wind has beautiful being of the applications of quality, they require a relatively powerful configuration all the same to function in a fluid way. The more modest users of machines can nevertheless turn to services Web proposing of the functionalities similar, but based on cards in 2d.

Google is obviously present in this field with Google Local (in the past Google Maps) which uses the same satellite images as Google Earth. Unfortunately, just like Google Earth, the service has of real interest only for the Americans, the aspect "guides proximity" being completely ineffective for the other countries, of which ours. Useless thus to seek a pizzeria in Bordeaux or Marseilles. On the other hand, not of problems for New-yorkais.

The war that Google and Microsoft are delivered on the Web obviously led this last to propose its own alternative to Google Local, Windows Live Local . As for Local Google, it is based at the same time on charts and images satellite, resulting from NASA.

The service proposes rather interesting functionalities. By taking again our search for pizzeria on New York, the service allowed us zoomer until an air sight of the street of the required pizzeria! For us other French, Windows Live Local is on the other hand of an interest even more limited, the French cities, including Paris, being locked on a level of very insufficient zoom.

Microsoft also gives access to beta of an interesting technology which consists in exploring a city through a series of multiple photographs in subjective sight, in particular effective to represent a route visually.

[ftvfatboy]

Future for the Services

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Which future for the services of cartography?

We are clearly with the stammerings of the type of applications suggested by Google Earth or NASA World Wind. Already very impressive, those must nevertheless make with some limitations: whatever the software used, it always arrives a moment when the sight becomes fuzzy. Google Earth proposes its sight "buildings", but one begins to dream of modelings even more detailed of the streets. This progress themselves is limited by the colossal task that the virtualisation of our planet represents and inevitably influenced by their geographical origin. For the moment, the two software headlight is American. Google Earth has a very significant Community support which largely helps to fill the international gaps of the software. Multiple projects are born: the near total of Germany thus has been just covered in high resolution and a project of modeling of the streets of London is in hand. Nevertheless, the software takes all its direction only if one lives in the United States or that one projects to go there. In the state, the "local" side of this type of services is still far from being exploitable for other countries.

The most promising initiative remains "Google Earth French" promised by the IGN. Few information still filtered on this project, which should be partially paying, but it should restore a certain balance and to reach a level of detail without precedent of our territory the IGN thus promises a precision of a pixel for 50 cm thanks to photographs taken during mission of overflight in the plane. 400.000 stereotypes would be thus used to cover the hexagon and the DOM supplemented by 3600 charts sets of themes on the scale (excursions, river, drills, parks...). Partners as the Land register could them also bring their data. A video first of demonstration of the service is available since the blog of Jean Michel Billaut


While waiting, Google Earth remains currently the most advanced application in its kind and the "total" dimension of the software is as for it a mine of information on our planet. Good explorations!

[ftvfatboy]

Complete Video Compression Guide

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Complete Video Compression Guide

We will start with basic discussions of analog and digital video, continues with the principles of video compression, and concludes with a description of three compression methods designed specifically for video, namely MPEG-1, MPEG-4, and H.261.


Analog Video

An analog video camera converts the image it “sees” through its lens to an electric voltage (a signal) that varies with time according to the intensity and color of the light emitted from the different image parts. Such a signal is called analog, since it is analogous (proportional) to the light intensity. The best way to understand this signal is to see how a television receiver responds to it.


The CRT

A television receiver (a CRT, or cathode ray tube), is a glass tube with a familiar shape. In the back it has an electron gun (the cathode) that emits a stream of electrons. Its front surface is positively charged, so it attracts the electrons (which have a negative electric charge). The front is coated with a phosphor compound that converts the kinetic energy of the electrons hitting it to light. The flash of light only lasts a fraction of a second, so in order to get a constant display, the picture has to be refreshed several times a second. The actual refresh rate depends on the persistence of the compound . For certain types of work, such as architectural drawing, long persistence is acceptable. For animation, short persistence is a must.

The early pioneers of motion pictures found, after much experimentation, that the minimum refresh rate required for smooth animation is 15 pictures (or frames) per second (fps), so they adopted 16 fps as the refresh rate for their cameras and projectors. However, when movies began to show fast action (such as in westerns), the motion pictures industry decided to increased the refresh rate to 24 fps, a rate that is used to this day. At a certain point it was discovered that this rate can artificially be doubled, to 48 fps (which produces smoother animation), by projecting each frame twice. This is done by employing a double-blade rotating shutter in the movie projector. The shutter exposes a picture, covers it, and exposes it again, all in 1/24 of a second, thereby achieving an effective refresh rate of 48 fps. Modern movie projectors have very bright lamps and can even use a triple-blade shutter, for an effective refresh rate of 72 fps.

The frequency of electric current in Europe is 50 Hz, so television standards used there, such as PAL and SECAM, employ a refresh rate of 25 fps. This is convenient for transmitting a movie on television. The movie, which was filmed at 24 fps, is shown at 25 fps, an undetectable difference. The frequency of electric current in the United States is 60 Hz, so when television came, in the 1930s, it used a refresh rate of 30 fps. When color was added, in 1953, that rate was decreased by 1%, to 29.97 fps, because of the need for precise separation of the video and audio signal carriers. Because of interlacing, a complete television picture is made of two frames, so a refresh rate of 29.97 pictures per second requires a rate of 59.94 frames per second. It turns out that the refresh rate for television should be higher than the rate for movies. A movie is normally watched in darkness, whereas television is watched in a lighted room, and human vision is more sensitive to flicker under conditions of bright illumination. This is why 30 (or 29.97) fps is better than 25. The electron beam can be turned off and on very rapidly. It can also be deflected horizontally and vertically by two pairs (X and Y) of electrodes. Displaying a single point on the screen is done by turning the beam off, moving it to the part of the screen where the point should appear, and turning it on. This is done by special hardware in response to the analog signal received by the television set. The signal instructs the hardware to turn the beam off, move it to the top-left corner of the screen, turn it on, and sweep a horizontal line on the screen. While the beam is swept horizontally along the top scan line, the analog signal is used to adjust the beam’s intensity according to the image parts being displayed. At the end of the first scan line, the signal instructs the television hardware to turn the beam off, move it back and slightly down, to the start of the third (not the second) scan line, turn it on, and sweep that line. Moving the beam to the start of the next scan line is known as a retrace. The time it takes to retrace is the horizontal blanking time.

This way, one field of the picture is created on the screen line by line, using just the odd-numbered scan lines. At the end of the last line, the signal contains instructions for a frame retrace. This turns the beam off and moves it to the start of the next field (the second scan line) to scan the field of even-numbered scan lines. The time it takes to do the vertical retrace is the vertical blanking time. The picture is therefore created in two fields that together make a frame. The picture is said to be interlaced. This process is repeated several times each second, to refresh the picture. This order of scanning (left to right, top to bottom, with or without interlacing) is called raster scan. The word raster is derived from the Latin rastrum, meaning rake, since this scan is done in a pattern similar to that left by a rake on a field. A consumer television set uses one of three international standards. The standard used in the United States is called NTSC (National Television Standards Committee), although the new digital standard is fast becoming popular. NTSC specifies a television transmission of 525 lines (today, this would be 29 = 512 lines, but since television was developed before the advent of computers with their preference for binary numbers, the NTSC standard has nothing to do with powers of two). Because of vertical blanking, however, only 483 lines are visible on the screen. Since the aspect ratio (width/height) of a television screen is 4:3, each line has a size of 4/3 of 483 = 644 pixels.
The resolution of a standard television set is thus 483×644. This may be considered at best medium resolution. (This is the reason why text is so hard to read on a standard television.)The aspect ratio of 4:3 was selected by Thomas Edison when he built the first movie cameras and projectors, and was adopted by early television in the 1930s. In the 1950s, after many tests on viewers, the movie industry decided that people prefer larger aspect ratios and started making wide-screen movies, with aspect ratios of 1.85 or higher. Influenced by that, the developers of digital video opted for the large aspect ratio of 16:9.

[ftvfatboy]

Composite and Components Video

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Composite and Components Video


The common television receiver found in many homes receives from the transmitter a composite signal, where the luminance and chrominance components [Salomon 99] are multiplexed. This type of signal was designed in the early 1950s, when color was added to television transmissions. The basic black-and-white signal becomes the luminance (Y ) component, and two chrominance components C1 and C2 are added. Those can be U and V , Cb and Cr, I and Q, or any other chrominance components. Figure 6.5a shows the main components of a transmitter and a receiver using a composite signal. The main point is that only one signal is needed. If the signal is sent on the air, only one frequency is needed. If it is sent on a cable, only one cable is used.

Composite video is cheap but has problems such as cross-luminance and crosschrominance artifacts in the displayed image. High-quality video systems normally use component video, where three cables or three frequencies carry the individual color components (Figure 6.5b). A common component video standard is the ITU-R recommendation 601, which uses the YCbCr color space (page 626). In this standard, the luminance Y has values in the range [16, 235], whereas each of the two chrominance components has values in the range [16, 240] centered at 128, which indicates zero chrominance.

[ftvfatboy]

Digital Video

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Digital Video



Digital video is the case where the original image is generated, in the camera, in the form of pixels. When reading this, we may intuitively feel that an image produced this way is inferior to an analog image. An analog image seems to have infinite resolution, whereas a digital image has a fixed, finite resolution that cannot be increased without loss of image quality. In practice, however, the high resolution of analog images is not an advantage, since we view them on a television screen or a computer monitor in a certain, fixed resolution. Digital video, on the other hand, has the following important advantages:

1. It can be easily edited. This makes it possible to produce special effects. Computergenerated images, such as spaceships or cartoon characters, can be combined with reallife action to produce complex, realistic-looking effects. The images of an actor in a movie can be edited to make him look young at the beginning and old later. Editing software for digital video is already available for most computer platforms. Users can edit a video file and attach it to an email message, thus creating vmail. Multimedia applications, where text, sound, still images, and video are integrated, are common today and involve editing video.

2. It can be stored on any digital medium, such as hard disks, removable cartridges, CD-ROMs, or DVDs. An error-correcting code can be added, if needed, for increased reliability. This makes it possible to duplicate a long movie or transmit it between computers without loss of quality (in fact, without a single bit getting corrupted). In contrast, analog video is typically stored on tape, each copy is slightly inferior to the original, and the medium is subject to wear.

3. It can be compressed. This allows for more storage (when video is stored on a digital medium) and also for fast transmission. Sending compressed video between computers makes video telephony possible, which, in turn, makes video conferencing possible. Transmitting compressed video also makes it possible to increase the capacity of television cables and thus add channels. Digital video is, in principle, a sequence of images, called frames, displayed at a certain frame rate (so many frames per second, or fps) to create the illusion of animation. This rate, as well as the image size and pixel depth, depend heavily on the application. Surveillance cameras, for example, use the very low frame rate of five fps, while HDTV displays 25 fps.

Even the most economic application, a surveillance camera, generates 5×640×480×12 = 18,432,000 bits per second! This is equivalent to more than 2.3 million bytes per second, and this information has to be saved for at least a few days before it can be deleted. Most video applications also involve sound. It is part of the overall video data and has to be compressed with the video image. There are few video applications do not include sound. Three common examples are: (1) Surveillance camera, (2) an old, silent movie being restored and converted from film to video, and (3) a video presentation taken underwater. A complete piece of video is sometimes called a presentation. It consists of a number of acts, where each act is broken down into several scenes. A scene is made of several shots or sequences of action, each a succession of frames, where there is a small change in scene and camera position between consecutive frames. The hierarchy is thus piece- act- scene- sequence- frame.