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Multicriteria selection of trajectories in DFS Viewer

How to apply multicriteria selection for all trajectories and choose only the ones you want? With DataFromSky Viewer – sofisticated software for advanced traffic data interpretation and visualization, you are able to create not only the simple Origin Destination Matrix, but with advanced setttings, the multi-criteria selection for the trajectories can be applied.

Following gif presents detailed process, how to do it:

Usecase shown in the gif
If you want to track particular path and see how many vehicles have used that combination, a selection tool can be used.
In step 1, selection criteria for Entry and Exit gate were defined and all the trajectories, which have not used this combination were removed. After this selection, 4 trajectories remain.
Step 2 – As we wanted to know, how many cars leaving the service station in the South exit will turn right on the crossroad, another selection critera was applied. This condition specifies that only trajectories, which have used the combination Entry gate: south exit of the service station and Exit gate: turning right on the traffic lights, will be shown. Finally, only 2 trajectories left, which fulfill all the above defined criteria.

Why is the multi-criteria selection useful?
– show only the trajectories you want
– monitor and analyze traffic behavior in a defined way
– monitor time cars spend in service station / facilities
– find traffic patterns, identify problematic zones

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New version of Viewer

We have a new version of Viewer! You can download it at the home page, or use this direct link. The list of differences includes a lot of things, so let’s take a look at them one by one.

Gate angular sensitivity illustration

Gate angular sensitivity

Gates can count objects, and filter them based on their type. When we had to cope with chaos on the road in both directions, we added directionality. But sometimes all objects come chaotically from all directions, such as pedestrians. What then?

We now added a new setting for gates, where it is possible to select the angles under which objects must come. If their direction falls outside this angular range, the gate will not register them. With this functionality it is possible to handle yet another level of chaos and uncertainty, should you chance to record such behaviour.

On the left is a mock picture of the concept. Both gates have directionality set. The entry gate (15) has angular sensitivity of 90 degrees and the exit gate (7) has angular sensitivity of 15 degrees. Without directionality, the cones that depict the angle ranges would be on both sides. Note that angle of 90° means a right angle on both left and right: A bi-directional gate with angle of 90° (both default values) in fact accepts 180° on both sides, or 360°, and does not discriminate at all.

distance_measurement

Distance measurement

Now, DataFromSky Viewer users can measure exact distances between two or more points – even if there’s no road. This function is particularly helpful for a traffic engineer. To start using the new distance measuring tool, right click on any point on the image, and select “add point”. Then define another point on the image in the same way, and you will see the distance between them.

The precision depends on the quality of geo-registration procedure, but it is often better than 40 centimeters. The distances are showed in meters. You can also add multiple points to measure distances between them. If you make a mistake, select the point and move it on the right position.

Difference between detected and actual vehicle center

Vehicle center projection

This is not a feature of Viewer, but yet another good news, so here we go! We silently added this in the last months and forgot to mention it. We now project vehicle definition points onto ground. Typically, they lie in the visual center, but not actual vehicle center. This may not seem like much of a difference, but we missed somewhere between 0.2 to 1 meter that way! More importantly, this error is not homogeneous in any practical way, only for vehicles of the same height at the same place. Given that we meticulously correct for perspective and other factors, losing so much precision was not an option – particularly now that we started systematic work on precision and error quantification and improvement.

Improved load and playback speed

Speed is something that one expects naturally from modern computers and software. This is not always possible with lots of visual data, as in our case, but not always impossible either! Now that we are working on (and with) Viewer in earnest, we focused on speed as well. Believe it or not, but sending numbers to show in the old vehicle list turned out to be a drag. Another thing that ended up significantly faster was drawing all the lines, shapes, notes, boxes and texts on top of the video. Apart from this we changed a lot how the Viewer handles video under the hood.

We are confident that you will like how speedy the Viewer turned out, compared to how it was before!

Other

Apart from the visible things, many bugs were fixed.

The default download link is for 64-bit Windows. If you need a 32-bit version, get this one instead.

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Boxed version of DataFromSky Viewer is available!

We are pleased to announce that DataFromSky Viewer is available in a box version as well. And depending on your needs, this is not a bad option! Sometimes, a physical item is required. The box contains a DVD with the software, a printed user guide and DataFromSky brochure. Email, phone and Skype support can not be printed and put into the box, but are part of the deal, of course!

DFS Viewer Box Version

For more information about purchasing box version, please write to us at info@datafromsky.com or use our contact form.

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New functionality: Flow visualization

A new function was added to DataFromSky: Traffic flow visualization. Instead of collecting vehicle counts from manually defined combinations of gates, one can now get a fully automatically generated overview of the situation. Take a look at the pictures below to compare the old and new ways:

Normal view – a tangle of trajectories


New view – trajectories’ aggregation


What happens behind the scenes is that the trajectories are grouped according to their characteristics and the resulting trajectory groups visualized according to their average. Needless to say, the DataFromSky team is pleased to bring another of computer science concepts – clustering – into practical use in the field of traffic engineering.

Of course, the trajectory clustering is again only another stepping stone on which one can build further. Even the most rudimentary statistics inside the trajectory groups allow getting at more and more interesting kinds of information. Let’s say… Automatic detection of fastest path, extracting the associated speed, time spent in roundabout etc., comparison with the rest of the group,… As always, there is much space to grow and improve. As we all know – the sky’s the limit!

As the academic year is coming to its last weeks, the DataFromSky protégés which you already heard about will boost the team shortly. So look forward to more news of this kind, and if you have an idea for a function, type of data, that can be extracted from the currently available information, we are ready to listen!

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