Getting Started Getting StarTraX loaded and ready to replay your track file will be your first priority.

Controlling the replay How you use all the buttons and controls that allow you to manage your track replay.

Making the replay realistic Some of what goes on "behind the scenes".

Track Information A reference section about the information available about your track.

Gliding features If your sport involves un-powered flight then this section will be of interest to you.

Usability This section brings together a bunch of features that have been developed to make StarTraX easy and intuitive to use.

Release History This is where we document its development.

Thanks to the assistance of some dedicated volunteers who have undertaken a major translation task, StarTraX now operates in a range of languages. You can see the fruit of their labo(u)rs by clicking on the following flags :

Getting Started

You will be reading this section after you have downloaded the StarTraX installer from the gpsAnimator web site and installed it on your computer. You will now have a StarTraX icon on your Desk Top and a StarTraX entry in your Start/Programs list, either of which will start the StarTraX program.

Since StarTraX interacts directly with the Google Earth web site, you will need to be connected to the Internet for it to run.

Starting StarTraX

Once installed, you can find StarTraX in your familiar Start/Programs folder:

If the icon doesn't get replaced with the next screen after a few moments, then it indicates that you have a problem connecting with Google Earth.

Check your internet connections and start again

Control buttons - before a track file is loaded

The buttons that are active appear bold, inactive buttons are "greyed out"

After selection of your track file

Start and Pause the replay

Track Progress Indicator

Fast forward display speed

The higher the replay speed, the faster the images have to be displayed. This will inevitably result in some loss of clarity.

When your track is loaded, it is displayed in Google Earth as a series of lines joining your GPS track points. A numbered placemark is displayed every ten track points.

At the end of your track the replay will stop. If you try to re-start at the end, it will alert you with End of track - re-select a start point.

Controlling the replay

Now that you are up and running, this section describes in detail all the buttons and controls that allow you to manage your track replay.

The Menu

Settings

Track Selection

The first step in the animation process is to get StarTraX to read your track log file. The Go To button allows you to select a track file that you have saved previously to your computer. It opens the familiar Windows Explorer dialog box displaying all files with extensions that it can handle. These are: "gpx", ".igc", "nmea" and "plt".

You can also open a track log file in StarTraX using the Windows "Open With" feature.

You can also open multiple track files simultaneously using the "Multi track" feature.

Once the track file is selected, StarTraX reads the file and subjects the data to some serious analysis before displaying the track in the Google Earth window as a multi-colored line with a series of numbered points along its length.

Select start point

Selecting a track and start point when multi-tracking

When you have more than one track loaded, you may wish to be a bit more particular about which point of which track you want to start the animation.

If you select a new track by clicking on an un-selected track, then the points for the newly selected track will be displayed. This will allow you to review the available tracks and points and select the point on the track at which you want to start the animation.

The Cancel button will cancel any selection made.

Synchronize the tracks

Control the view position with mouse or buttons

When describing the viewing position we refer to a camera which is effectively recording the 3 dimensional (3D) world and presenting it on your computer screen in 2 dimensions (2D). So, whenever you see a Google Earth scene, it can be thought of as having been taken by a camera positioned at a certain location (latitude and longitude), at a certain altitude, facing in a certain direction (North, East, etc), with a tilt in a number of degrees above or below the horizontal, and with a roll angle, where the camera is rotated along its centre axis.

You can control the location (latitude, longitude, altitude) and orientation (heading and tilt, but not roll) of the camera in StarTraX with either the buttons or the mouse. In all cases, when the animation is running, StarTraX will endeavour to keep the target point in the centre of the screen. In practice, this is not always completely achieved due to the competing pressures of calculations.

Control the Camera with the Mouse

In addition to the camera control buttons described above, you can also control the camera with the mouse using gestures similar to those provided in Google Earth. They rely on you having a mouse equipped with a mouse wheel configured in the standard Windows fashion.

Pan left and right

With the mouse wheel pressed, move the mouse left and right.

Tilt down and up

With the mouse wheel pressed, move the mouse forward and back.

Zoom in and out

Roll the mouse wheel forward and back to zoom in and out.

Three view modes

The three view modes allow you to Control the way the camera follows the target point.

You can modify the dissipation behaviour of the smoke trail with the Smoke Trail length buttons

Short : The "smoke trail" fades after 1/2 minute.

Med. : The "smoke trail" fades after five minutes.

Long : The "smoke trail" does not fade.

Models

When StarTraX loads a track file, it makes a model selection based on the theme it deduces from your track. These models have been selected from Google Earth's huge "warehouse" of models that enthusiastic virtual model builders have been constructing and providing for our enjoyment. It's at http://sketchup.google.com/3dwarehouse/ if you want to check it out.

The Models menu enables you to make your own model selection from the Menu -> Models option.

We are deeply indebted to all the enthusiastic model builders for this rich resource of models.

Here are some of my favourites:

The ME109

the Audi Le Mans

The 747

Include your model

If you build or find a model that you would like included, send us an email containing link to the model and we'll consider it for inclusion. We have to do a bit of work on most models before they can be included.

If you are building or manipulating models for inclusion in StarTraX then the following tips will make our job a little easier:

Model type: Google Sketchup (.skp)

Orientation: have it facing towards the green axis, so that in its normal position it is going away from you.

Location:

a)      positioned with vertical axis through the viewer's position with vehicles, this is the position of the driver's head.

b)       Positioned with the base of the model (wheels) on the ground

Scale: realistic. Some models are scaled very small or very large

We calculate, store and use a value of the height of the pilot's eye above the ground for each model

Multiple file formats

The major enhancement in 3.6 is a change in the method of handling track file formats. Initially (because that's where we came from) we only handled the .plt file format from OziExplorer .plt. later enhancements introduced gpx, nmea and kml formats. Now that we have realized just how many formats there are "out there" we have taken the following approach.

The "native" file format that StarTraX handles is gpx version 1.1.

GPX is an open standard for recording GPS data. There are a number of free applications that will read data from a range of GPS devices and save them to the GPX format, with a .gpx file name extension, including GpsBabel and EasyGPX.

There are two GPX formats 1.0 and 1.1. GPX 1.1 was released in 2004 and is the only version that StarTraX will accept.

To handle other formats we have incorporated GpsBabel into StarTraX to convert files to the gpx format. This happens "in the background" you will see GpsBabel briefly flashing on the screen when you ask for a non-gpx file to be loaded.

We use GpsBabel to convert your non-gpx files to gpx and save the new gpx file in your %TEMP% (by default C:\Documents and Settings\{user}\Local Settings\Temp) directory before loading them into StarTraX.

Currently we handle the following formats through GpsBabel:

In this version we have added the FAI/IGC Flight Recorder Data Format .igc format to the list of available formats. Over time, as users request more formats, we will incorporate them into StarTraX.

Meanwhile, if you have a format that is not in the above list, you can use GpsBabel to convert them to gpx version 1.1 and StarTraX will happily process them.

Multi-track

For those of you who engage in your activity with GPS-equipped friends or competitors, you can now replay all your tracks together in StarTraX.

To access this feature, you first place the track files that you wish to simultaneously replay in a single Windows Folder. You then click on the Multi-track check box in the Settings tab of the Menu option. This will Enable multiple tracks to be displayed together.

When checked, the file selection dialog box, opened from the GO TO button, allows you to select multiple track files with familiar Windows mouse gestures:

To select files individually, use Control + Click (hold down the control key and use the mouse to click on the files you want to open).

To select a range of files, use Shift + Click and select multiple adjacent file names from the display.

When you click the Open button, StarTraX reads the files one by one and presents them in the Google Earth window.

You might have to be a bit patient here as there's heaps of work going on in the background to calculate the position of the points and display them in Google Earth.

The tracks are separately colored and are labelled A, B, C etc.

The feature has been developed primarily for paragliders, and will load a different colored paraglider for each track.

Not that it's likely to bother you, but there's a limit of 26 on the number of files that can be opened concurrently.

Multiple tracks in a file

Some GPS software generates gpx files containing multiple, separately named tracks.

Track smoothing

Apply smoothing to your track to turn sharp turns into curves. GPS track data consists of a set of points recorded in your GPS at its own time intervals. GPS tracking is also only accurate to a few metres, so if you can record at high speed, you get high-speed zigzags, and if you record at low speed, you get further spaced zigzags.

What we have done is to take your points, at not less than 3 seconds intervals, and we have generated nine new points between each of yours, to form the sweet curve that you see below. The new points are just as "honest" as the original points as the new track still passes exactly through each of your recorded points. We have just eliminated the sharp corners.

StarTraX uses an algorithm to deduce a 3^rd order polynomial for a line between the second and third points in every 4 point sequence in the track, using the first and third segment to provide a starting and ending gradient.

It then generate nine new points along that line and add them to your track (with appropriate time stamps and altitudes).

But this is all done between loading the file and starting the replay, so it doesn't impinge on performance at all.

It took me a long time to find an appropriate approach to the smoothing task. Much of the material published on the web relates to "splines", which did not suit my needs as I was determined that the smoothed track would be as "honest" as the original track and would therefore have to pass through all the original points. The spline solutions provide a nicely smoothed track, but they do not religiously go through the all the original points.

I am indebted to a sailing mate who, as a nautical engineer, had an old textbook on computer methods for ship surface design. It contained the following page describing and detailing a Fortran subroutine it must have been 30 years old!

I still don't really understand the method but I converted to Visual Basic and implemented in StarTraX and after extensive testing, I'm satisfied that it does a good job. Thanks Malcolm.

Units of measure for distance and speed

Choose your preferred speed and distance units.

Different nationalities and different activities call for different units of measure of distance: kilometres, statute miles, nautical miles, feet and metres. These different distance units influence the derived values for speed: kilometres per hour, metres per second, miles per hour, feet per minute, knots.

This setting also changes the units Google earth uses when displaying altitude and distance when StarTraX is Paused. The screen shot below shows an example of the display when Metric units are selected.

And again, when Nautical is selected:

Time zone deduction and manual override

StarTraX deduces your time zone from your longitude, change the time zone in hours +/- UTC. It assumes that the time stamps in your track file have been recorded in UTC (GMT).

It deduces the local time zone from the longitude of the track (actually just the first point) and displays the GPS time (File:) and local time (Local: ) in the point display and the display window. It calculates the time zone by working out in which 15 degree segment of longitude the point lies, and adds or subtracts one hour for each segment. (360 degrees / 15 = 24 hours)

It makes no allowance for Daylight Saving time or for local time zone variances. You may override the calculated time zone by entering a new value in the Zone entry field box.

If you are playing a track that was recorded in a different time zone than your PC is currently in, then GE will calculate the local time based on your current location, not the track's location.

Un-timed tracks

Google Earth layers street, buildings, borders

The only reason you might want to change these settings would be if your view was too cluttered, or if the loading of the layers slowed down the performance.

Scenery

Included scenery

These are scenery files we have found on the internet or generated ourselves. If you have any files (kmz, kml) you would like incorporated, email the file(s) or their URL to us (at info@gpsanimator.com) and we'll include them. The files are downloaded by StarTraX from our web site at run-time, so no software update is required to deploy an update. We have assembled a small (but hopefully growing) selection of scenery that you might enjoy. If you navigate (via the GE side of StarTraX) to their areas, you will see them displayed. They are mainly ski-runs and lifts.

Local files

You can Show or hide the scenery layer from the Show Scenery Layer check box:

Tracks in Scenery files

If your file contains KML "lineString" features, they will be available as tracks in the track selector opened by the GoTo button.

For this type of track to be available in StarTraX, the linesString feature in the kml file must have a value in the <name> attribute. This is not a requirement of kml, so if your file contains lineString features without a name, they will not be playable in StarTraX.

Surface(Aerial)? override

You will only need to use this control in the unusual circumstance that your track encompasses both aerial and surface components, or if StarTraX is unable to determine the nature of your track and you wish to Switch the track style between being "in the air" and "on the ground". . I have a track that includes the flight to the ski fields (aerial) and the day skiing (surface). StarTraX struggles to determine whether you want to view the aerial or surface component of the track. This check box allows you to override StarTraX's determination and display the track on the surface or using the altitude recorded by your GPS (aerial).

Making the replay realistic

This section describes features over which you have no direct control which make StarTraX a realistic replay experience.

Google Earth interface

StarTraX relies entirely on the truly amazing Google Earth to display your moving track in 3D space. In mid 2008 they released a new and powerful method (the Google Earth API "GEAPI") for programmers (like me) to interact directly with the GE globe and have regularly released enhancements and improvements to the interface. And of course they continue to release more and more detailed imagery on a regular basis.

This has provided an amazing 3-Dimensional space for developers like me to play in. We don't have to worry about so many of the complexities of working in a 3D space maps, land form, ground texture, scale and projection of a 3D world on a 2D computer screen. This is all handled by GE, all we have to do is to tell GE to put our model aircraft at a certain location (latitude, longitude, altitude) and show it as if from a camera positioned at a certain location, pointed at the model. The underlying language used for sending these instructions to GE is called KML whilst the interface to the KML is via the Google Earth API

So, what you see in the right hand pane of StarTraX is entirely courtesy of Google Earth: the landscapes created from satellite photography draped over an underlying structure of ground contours, with layers of streets, borders, town names and 3D buildings with your 3D avatar appropriately located, scaled and oriented in the landscape.

Progresses in real time you see your trip as it happened

At run-time, your position and the camera position are re-calculated around 60 times a second based on your previous position and your current speed and direction. GE is then instructed to move the target model and the camera to the new point. GE then has to re-draw the scene based on these new positions.

Smooth camera pan and tilt

Because the GPS track is a series of points, the track you see is a series of straight lines linking the points. This means that after the camera has followed the target along one segment, it has to re-position abruptly to follow it along the next segment. With small direction changes this wasn't a problem, but with large ones especially when the track is a glider orbiting in a thermal, the abrupt camera position changes led to some very abrupt changes of view.

In earlier versions we were relying on GE to provide a smooth transition from one camera position to the next, but this was not always effective, so we now control these camera transitions by anticipating the next segment turn and tilt angle and start to move the camera into the next position at the start of the segment, so that once the target has reached the start of the next segment, the camera has been swung into position for this next segment.

we link the camera panning with thermalling (gliding in climbing orbits). When thermalling, the camera pans continuously, at a rate determined by the turn angle. When not thermalling, the camera pans at a fixed speed, starting later in the segment, just in time to get the orientation correct at the end of the segment.

Realistic banking

Whilst generating the smooth track above, we can also work out the G-force that would have been generated in the turn and have visually represented it by banking the model appropriately. So now when the paraglider turns into the thermal, or the skier carves into a tight turn, you can see the model doing exactly the same thing.

The above shots were taken whilst in Observe mode. When in Follow mode, the camera also banks, providing a realistic replay. We have drawn in the horizon in the shot below to emphasise the point.

We have extended this banking to all tracks, not just those modified with the track smoothing feature.

Track Theme derived from track data

StarTraX analyses your track to interpret your activity. It determines which of the following themes that the track most closely matches. I'm not giving too much away about this process except to say that it analyses the points in the track for speed, altitude, and vertical speed and categorizes the track into one of the following categories which I have called Theme.

Whilst this works in general, it can get confused when the characteristics are not consistent throughout the track. For example, I have a track of a journey from Sydney to a ski resort in Japan, which includes two flights, a train and bus trip and an afternoon skiing. StarTraX deduced Acft-Light.

It re-assesses the theme each time you load a new track. The theme it deduces is displayed in the in the file display:

Once it determines the Theme of your track it displays an appropriate model to represent your activity, like a skier, car, boat etc.

Ground altitude

If it can deduce the ground altitudes then it uses the ground altitude rather than the GPS altitude when following Surface (as opposed to Aerial) tracks. This provides a more realistic replay as the altitude that the GPS device records can often be 10's of metres above or below the ground surface that Google Earth uses in the display. Using the GPS reported altitude in these cases would cause the track to be displayed above or below the Google Earth surface.

You may wonder why we go to this effort, as GE allows lines and points to be drawn "clamped to the ground" . Well, the answer is that we do it to improve the way the camera works. By retrieving the ground altitude at both ends of each segment, we can calculate the actual tilt of the track, and position the camera accordingly. This may not seem a big issue, but it was a problem when following a skiing track down the mountain. With no actual ground altitude, we couldn't get the excitement of pointing the camera down to follow the track down a steep section.

Smooth replay tricks

A significant proportion, probably 30%-40%, of the development effort has been spent on getting a smooth replay eliminating the jerkiness from the target point movement and moving the camera smoothly.

As you probably know, movement that you see on the screen of your TV, cinema screen or computer is not actual movement at all but the display of slightly changing images in rapid succession. The frequency with which the images are displayed is called the "frame rate", usually measured in frames per second (fps). The minimum frame rate required for the human eye to perceive smooth motion is influenced by brightness, image blurring etc and is the subject of extensive study. Cinemas work at 24 fps but use image blurring to enhance the effect. TV's work at higher rates.

The challenge we faced was to complete all the calculations required to generate the next frame and have them displayed in Google Earth within the allotted time frame. After much blood, sweat and tears, we have managed to streamline the code sufficiently to achieve a frame rate of around 50 fps when running on a basic PC with a standard video card.

StarTraX doesn't run in isolation on your computer the Windows operating system is managing the computer and is allocating computer resources CPU cycles, and memory, to all the processes running on your box according to that process's priority. StarTraX runs at the highest possible priority and we assign the lowest priority to the Google Earth component, which runs as a separate process. This means that occasionally the background scenery in GE is a bit slow to refresh, but we chose that as an acceptable compromise in the search for a smooth replay.

Up to a point, you'll get a smoother replay on a more powerful computer or a higher quality video adapter. On the other hand, running on a slower computer, or one that is burdened with other tasks, like an office server or a Mac running Windows or VM, may result in degraded performance.

Track Information

This section describes features that provide you with information about your track.

Animated track overview

Numbered points

Track Profile

This graphical analysis tool, which Display your track as a graph of speed, altitude etc. by time or distance... allows you to do some serious evaluation of your performance. It is launched from the button.

StarTraX will continue to replay your track while the profiling screen is displayed in a separate window.

Flight instruments

The Cockpit Instruments check box causes StarTraX to Display all the flight instruments. when the track is playing.

Speed Indicator

Compass

Viewing Direction

The viewing direction is indicated by the position of the rotating compass ring relative to the fixed marker.

The compass ring rotates as you change your viewing direction.

Track Direction

The track direction is indicated by the position of the nose of the rotating aircraft symbol.

The track direction indicator rotates according to your track direction.

Altimeter

Variometer

Smoke trail

Track color

Display Details

Hide track when running.

Some users like to Control if the track remains displayed while the replay is running., some don't. This provides the flexibility of choice.

This shows the track hidden

Here, the track is not hidden:

Start Point

Point information display

Track Details displays

File details

Point details

Disp Dists.

The "check box" defaults to un-checked. When checked, it will Display the distance from the start next to the track point.

Gliding features

StarTraX has been adopted by a significant number of enthusiasts of un-powered flight hang-gliding, paragliding and gliding and they have triggered the development of a number of features specific to their sport.

Colour the track by: VSI

The allows you to Control the colouring of the track lines. You can Colour the track by speed. (default) or Colour the track by VSI.

Clouds over thermals

Clouds can be generated above orbiting glider tracks. As a visual clue to the size and location of thermals, we've positioned a white, semi-transparent cloud at the top of each thermal, whose height is proportional to the strength of the thermal.

It's semi-transparent so as to not be too intrusive. The thermal strength is measured simply as the value of the height gained in the thermal (not the rate of climb, which could be a thought for the future).

They are only generated for gliding, paragliding or hang-gliding tracks.

You can toggle the visibility of the clouds from the Show Clouds check box on the Settings Menu.

Wind speed and direction when gliding

This feature only works for glider, paraglider and hang-glider tracks as it depends on orbiting tracks to determine the wind speed and direction.

It analyses the way your GPS speed varies as your heading changes through a series of orbiting turns. If you maintain a constant airspeed, then, when you head upwind your GPS speed will be lower than when you head downwind.

This can be seen from a typical thermalling track:

StarTraX looks for portions of the track that display orbiting behaviour and uses the variation in the track's speed as it changes direction to mathematically deduce the wind speed and direction.

It makes the fundamental assumption that you have maintained a constant airspeed during the manoeuvre which of course is impossible in practice, but works pretty well on average.

The coloring indicates the wind speed, using a similar palette as for track speed, using the following colors and text to indicate the speed. We used the traditional Beaufort scale (http://en.wikipedia.org/wiki/Beaufort_scale) to classify the wind speeds, and made the assumption that no-one would be gliding in winds over force 5:

To accommodate the reality of wind conditions at different altitude levels, we re-calculate the wind for every 1000 ft of vertical altitude. So, if you entered the thermal at, say, 5253 and exited at say, 8312 then we'll calculate the wind at the four levels: from 5253 up to 6253, 6253 up to 7253, 7253 up to 8253 and 8253 up to 8312.

IGC Altitude source

Control which altitude is used in IGC files with barometric and GPS altitudes. The IGC format, widely used by pilots of gliders, paragliders, hang gliders etc, allows for the altitude determined by the GPS ("GPS altitude") and the altitude recorded by the barometric altimeter ("pressure altitude") to be recorded against each point. These two readings are always different for a number of perfectly valid reasons that we won't go into here. As StarTraX started out to be a GPS track animation program and it can only display a track with one altitude, we originally took the decision to ignore the pressure altitude and to rely on the GPS altitude when animating these tracks.

However we have gone back to providing you with the option of loading either track once you have selected a file that contains both the pressure altitude track "PRESALTTRK" and GPS altitude track "GNSSALTTRK". (These names were dreamt up by other folks, so don't shoot the messenger.)

If you're not loading IGC files, or if your IGC files only have one altitude, then this control has no effect on the way they're handled.

If they do have both sources, then you have three options:

Ask: Prompt for a decision at run-time. StarTraX will present you with the track selector every time you load a file with both types of altitude it will prompt you with Please note: IGC files may contain both barometric altitude from the altimeter (PRESALTTRK) and GPS altitude (GNSSALTTRK). Set your preferences in Menu->Settings->IGC Alt source
GPS Alt.: Use the GPS altitude.
Baro Alt.: Use the barometric altitude.

Route and turn points (IGC files)

This feature has been developed from IGC gliding files downloaded from the OLC and bgaladder sites. Bearing in mind that StarTraX doesn't directly read IGC files, it relies on GpsBabel to convert them to GPX format, we have found that GpsBabel identifies this data and records it in the GPX rte (route) and "rtept" (route point) elements.

If you have GPX files with these elements then you should get the same result.

Different models when loading multiple paragliding tracks

Usability

This section describes features that are aimed at simplifying and streamlining your sessions in StarTraX.

"open with"

In Windows, you can associate an application or program with a file type, like Word for .doc, Excel for .xls, Notepad for .txt.

You can now make StarTraX the "Open With" program for your track files, and then if you applied this to your IGC and/or GPX files, then a double-click on the file the file in Windows Explorer will open the file in StarTraX.

If you use this technique to open a file whilst StarTraX is already playing a track, it halts the current track and opens the new track.

If you have "Multi-Track" selected, it will open the new track as an additional track, leaving the previous track(s) loaded, otherwise ("Multi-track" not selected) it will replace the existing track with the new track.

"Open with" is a Windows feature that is well documented here .

Settings retained

There is an almost bewildering array of buttons and check-boxes available to you to customize your track replay choices. Imaging having to re-select them each time you started StarTraX. To save you that inconvenience, we assume that you will normally like to retain your settings from one session to another, so the settings marked with an asterisk : will be retained from one session to the next. If you're interested, we store them in the Registry at :

Obviously we do not encourage you to make any changes here!

Version display and check

To retrieve version information from StarTraX, right-click on the GPS image:

It reports the versions of StarTraX and the Google Earth components: the Browser Plugin, GEPlugin and the development API, GeAPI.

Google Earth periodically updates its software which is automatically updated on your computer.

Every time StarTraX starts, it checks the web-site at http://www.gpsanimator.com to see if there is a newer version available. If there is, it generates the message: There is a new version of StarTraX available. Please download it from the web site at gpsAnimator.com. A new registration key is NOT required to run this version.

notifying you of your revision number and the revision number of the version available for download from the web site.

Tool tips

Computer monitor size recognition

Different PC's have different monitor sizes with associated screen resolution. To provide as much detail as possible in the Google Earth frame, StarTraX adjusts the size of the Google Earth frame to fill the monitor.

So, on a standard 1024 x 768 monitor you get

On a monitor with 1280 x 1024 resolution you get the same sized left hand panel, but more space for the GE frame

Whilst at 1900 x 1600 you get even more space for Google Earth.

System requirements

StarTraX has been tested on XP and, as it's written in Microsoft VB 2005 .NET 2.0, is expected to run on Vista and Windows 7.

No versions for MAC or Unix, sorry, although there are users running it under Windows on a Mac. I suspect that the performance will be degraded as there is so much translation to get from Windows OS to the Mac's underlying OS.

It needs a minimum of 800 X 600 screen resolution (although it runs OK on a notebook with 640 x 480 resolution.)

Registration

Perhaps not a usability feature, but I had to put it somewhere!

To register StarTraX on your computer, you should go to the Registration Form of the web site and complete the Registration form.

The registration details are written to the registry on your computer and, because they are based on the MAC address of your network adapters (LAN, wireless network, Bluetooth, etc.) , they won't work on any other computer. If you change all your network adapter cards, which is unlikely, it will invalidate your registration. In that case please apply for a new registration key.

Acknowledgments

StarTraX is a project that has been developed independently from Google Earth, although it is totally dependent on the amazing functionality that is Google Earth.

We at gpsAnimator.com have developed an application as a speculative project to display four dimensional (latitude, longitude, altitude and time) GPS tracks in on a 2-dimensional computer screen.

On the way, we visited

• GPSVisualizer.com, who has a powerful tool to display GPS track files in Google Earth.
• TopoGrafiX.com who have a neat tool in EasyGPX which downloads GPS data to GPX file format.
• OziExplorer who have a great mapping program that interfaces with a range of GPS devices and creates .plt track files.
• forums.msdn.microsoft.com where we received useful advice on some of the trickier issues in developing in Microsoft's .NET environment
• gpsbabel.org who have an excellent tool for manipulating GPS data, including unloading it from GPS units and converting between formats.

Bugs and Help

We have done our best to deliver a reliable product, but as with so many things, we are only human and are therefore fallible. Please report any errors, bugs or oversights with an email to info@gpsanimator.com. Please be sure to include the version information and as much detail as you can.

You can also email us if you have any questions or suggestions for improvement to the program (or its documentation).

Program structure

We are occasionally asked about the development and structure of the program, so here is some information.

Development environment

The original development environment was Windows XP, Microsoft Visual Studio 2005 , .NET 2.0 and Visual Basic. In March 2011 we have upgraded our development environment as below.

Microsoft Windows 7

Visual Studio 2010

Visual Basic .NET 4.0.

The main impact to you will be in the installation or upgrade of StarTraX to version 3.9 or above will require the download and installation of Microsoft .NET 4.0. You will be guided through the download and installation of this upgrade and

Follow the prompts to download and install NET 4.0 it does take 5-10 minutes, (sorry!) and then a reboot

High-level description.

Initialization:

From the main form, it opens a webBrowser and writes an HTML page containing the JavaScript code to load the GE Plugin and around 20 JS functions to interact with GE that are called from later in the program using WebBrowser.Document.InvokeScript.

Load a GPS track:

Reads the selected GPS track from your track file (gpx, plt, nmea or limited kml) into an array of track point objects, one object per point

Does the polar transformation trigonometry to calculate and record the speed and direction of travel in each segment between each pair of points.

Generates a KML representation of the track and displays it in GE (using parseKml).

Start the animation.

When you start the animation, it calculates the expected (real-time) arrival time at each point and starts a timer with an interval of 100 ms.

Process the timer event

At every timer event, it does the trigonometry to calculate the target point's position (lat, long, alt) based on the speed and direction of the current segment based on the actual time elapsed since the last timer event.

Positions the target point model at this new point using invokeScript to call one of the JS functions (set up above in the webBrowser) which calls the getLocation().setLatLngAlt(lat, lon, alt) etc. methods to re-position the model in GE.

Calculates the camera's position (lat, long, alt, heading, tilt) using the currently active camera parameters (range, heading, tilt) relative to the target point and moves the camera to the new co-ordinates with a call to another JS function.

Bells and whistles

There are obviously many more features to the program (it runs to around 25,000 lines of code) that have not been described in this high level description. We have put a lot of time and effort into developing and refining the maths to provide a smooth and convincing animation that will remain "under wraps" for the moment

Release history

Version 4.1 August 2011

This is a major release with lots of enhancements

• International StarTraX. Text appears in selected language. Huge thanks to the contribution by the team of dedicated volunteer translators.
• Updated web site. A major style makeover of the original web site which now incorporates the user documentation and translation pages in the one site.
• New altimeter and variometer display in metric as well as US.
• Text buttons are all replaced with graphic icons.
• New position synchronization option
• New replay slider.
• New position the fast forward controls on the front screen.

Version 3.10.3031 April 2011

This is mainly a bug fix release, although there are a three minor enhancements.

• Bug fix: "When using the "open with' facility to load a new track, the new track is opened in a second instance of StarTraX , not the existing instance - was lost in the previous version." Fixed, when you open a second or subsequent track, the new track is displayed in the original instance of StarTraX.
• Enhanced the "open with" feature to retain the existing track(s) if multi-track selected.
• Bug fix: "When changing from Surface to Aerial track mode (and vice versa), the track remains on the ground but the model and smoke appear in the air". Fixed, the track is re-drawn correctly on the surface or in the air.
• Bug fix: "In the Multi-track Start Point Selection form, the start points aren't updated when you select a different track". Now, when you switch from track to track, the start points are updated to reflect the current track.
• Add the update of Google Earth's unitswhen changing StarTraX's units.
• Improve the detection of the start and end of a thermal when positioning the clouds.
• Bug fix: "Track profiling hangs on tracks with lots of points". We now sample the track data to display around 1000 points in each view. There's no significant loss of detail, but great improvement in performance

Version 3.9.3013 April 2011

• Track profiling without Microsoft Excel including navigation with mouse gestures
• Upgrade development to Windows 7 and .NET version 4.
• Fix to the way it remembers your track coloring setting.
• Added "altitude" to available list in the display text.
• Some work on replaying scenery tracks. Exclude un-named tracks from the selection box and present them in sorted sequence. Improve initial view of the entire track and a fix to ensure the speed units are correctly interpreted.
• Add a cross-hair cursor when you're controlling the view with the cursor.
• Enable "minimize" on the main form.

Version 3.8.3010 March 2011

• New display of current track in GPS screen, animated with position of all active tracks.
• New smoke trail dissipation. It now progressively fades and ultimately disappears after 1/2 a minute, five minutes or never.
• New web-based documentation (this document)
• Enable subsequent opening of StarTraX with "Open With" while current track is playing. Stops the current track replay and opens new track file(s)
• Resolved the IGC GPS and barometric altitude track hassle with a user option in the to select a preference for one or the other.
• New option to select All tracks in a multi-track file.
• Fix altitude displayed in selected units in balloon and track details.
• Bug fix to registration code validation when complex network devices.
• Fix un-timed gpx tracks, was not handling at all.
• Fix display of image loading progress.
• Fix smoke trail now shows segment completed, not current segment. More realistic.
• Fix wind speed calculation of thermalling flights. A math error resulted in understatement of wind speed.
• Change version numbering from xx.xx.xx to xx.xx.xxxx to assist code management.

Version 3.8.2 February 2011

• StarTraX is now able to be associated with a file type to "open with" from Windows Explorer. Double-click on your IGC or GPX file to open it directly in StarTraX.
• Route and turn points displayed from IGC files.
• IGC files load both the PRESALTTRK and GNSSALTRK and offer you the choice.
• Cloud visibility can be toggled on and off.

Version 3.8.1 January 2011

• Cumulus clouds on top of thermals.
• Manage process priority StarTraX to high, geplugin to low. Improves replay smoothness with minimal degradation of terrain refresh quality.
• IGC files load the PRESALTTRK not GNSSALTRK
• Fix to wait for new file's view to completely refresh before processing the track file. Stops ski tracks from loading as paraglider!
• Deduce Glider theme when orbit path detected in an Acft-Light track.

Version 3.7.3 December 2010

• Display co-ordinates in dd mm.mm (dd in degrees, mm as minutes and decimals) not dd.dddddd
• Link camera panning with thermalling (gliding in climbing orbits). When thermalling, the camera pans continuously, at a rate determined by the turn angle. Not thermalling, the camera pans at a fixed speed, starting later in the segment.
• Display wind direction in compass points (NE, ENE, E, ESE, etc) not degrees.
• Detects screen size when displaying on systems with multiple screens.
• Camera tilt is smoothed to eliminate jerky vertical movement.

Version 3.7.2 December 2010 A major release

Four new on-screen instruments:

Speed with both analogue and digital display

Compass - showing orientation and direction of travel

Altitude - with a realistic aviation display

Vertical speed (VSI) essential for gliding activities.

For gliding tracks, it now has an analysis of wind speed and direction with on-screen indicators in the compass rose.

Some replay enhancements including the introduction of banking for all tracks, improved camera smoothing of both heading and tilt.

A third viewing option to add to "Follow" and "Observe" called "Lock" which locks the camera onto the moving target to provide a realistic replay experience.

Plus a swag of minor fixes to little bugs.

Version 3.6.6 October 2010

A minor bug-fix release to resolve some issues in multi-tracking which under some circumstances caused all tracks to start at the same time.

It also included an upgrade to the start point selection interface while multi-tracking.

Attentive users will also note that we have removed the tilt (lean forward or back, "attitude" in aviation-speak) on the models when they are flying. We realized that in the "real world", the attitude of paragliders and other aircraft isn't directly related to their angle of climb, so tilting the models based on their angle of climb/descent wasn't very realistic.

It's still there for ground-based activities like skiing, cycling and driving (in cars).

Version 3.6.3 September 2010

This was a minor bug-fix release including the removal of unused reference code to reduce the size of the installation file from 15 to 9 Mb.

It coincided with, and was tested on Google's release of GE API 5.2.1.1588

Version 3.6.2 August 2010

In looking for ways to improve the realism of the replay I have to walk the tightrope between the desire to display a great deal of detail and at the same time provide a smooth animation both of which put enormous loads on the computer processor to perform immense numbers of calculations at blistering speeds. The fact that a domestic desk-top computer can come close to achieving this is a constant source of amazement and awe!

This release contains further enhanced the replay mechanism which have yielded a further major step up in replay smoothness. You can now zoom right into the cockpit of your fast moving aeroplane or hover 50 metres from your skier carving down a back run. You can follow your paragliders from a distance, or close in as they tightly circle in the thermal.

It's not perfect, I know but given the practical limitations of the processor in your desktop PC or laptop and your broadband internet connection, it's pretty good (even if I do say so myself!).

Experimenting continues with coding techniques to deliver even more realistic replays.

Some major improvements have also been made to the multi-tracking feature, providing a simpler method of loading multiple tracks by making multiple selections from the Windows File open dialog box instead of having to load each track separately. The details are explained in the User Notes installed with the program update.

Version information

Document version date August 2011

StarTraX Version 4.1