901

(8 replies, posted in General)

Hi pgendreau,
Be aware that you cannot really make speed measurements as in post #2 unless the various points of the trajectory are all on the same plane and this plane is perpendicular to the camera optical axis.

Tennis serve and stroke have many rotational component, it will be impossible to measure this in a 2D software. You may get better results with a pure side view.

902

(2 replies, posted in General)

I concur on what Chas said regarding zoom and shutter speed if your camera support changing these parameters. If you are using a webcam or similar device, place it so that what you want to see fills most of the image.

If you plan on making measurements, another important aspect is the calibration of the space. To make accurate measurements you should either make sure the camera is perfectly perpendicular to the plane on which you make all your measurements, or use the perspective grid to map a physical rectangle and make the measurements on that plane.

I'll try to do a more in depth post to compare the errors that can be expected from both calibration methods.

903

(2 replies, posted in General)

Hi everyone,
I apologize for the relative lack of news during the past months.

It doesn't mean there hasn't been new developments, quite the contrary actually.
There has been 177 revisions to the source code repository, the most ever between two versions.
A lot of changes, many under the hood, and many visible. The experimental version 0.8.21 is ready, I'm currently waiting for Avast antivirus to fix a false positive in their new virus signatures that put Kinovea into quarantine.

I'll do a video presentation of the changes because it'll be easier than a written description.
Some highlights:
- new cameras management (thumbnails, name aliases).
- new capture screen (dual recording, drawings outside image, free moving of the image, better zooming)
- custom keyboard shortcuts.
- human model with center of mass tool.

And more things that I'll describe in the video.
Cheers!

904

(6 replies, posted in General)

dynacyclepei wrote:

in ver 8.20 when I try to track the point tool, the tracking box does not appear and the trace line does not happen.  The marker does track the point correctly but it does not leave a line trace behind for visualizing the path.

Yes. The point tool (cross marker) is now using the same tracking system as the other tools. To get back the trajectory tool you need to directly right click the object you want to track and choose "Track path". Do not add the cross marker.

905

(3 replies, posted in Français)

Bonjour,
J'avais fait des tests sur le sujet il y a quelques temps sans que cela ne débouche sur une fonctionnalité, mais si je me souviens bien sur le principe c'était tout à fait faisable.

À l'heure actuelle les filtres (contraste, niveaux, etc.) sont uniquement disponibles en mode analyse, ce qui en limite sévèrement l'utilité. L'avantage étant qu'ils sont appliqués une fois pour toute sur l'ensemble de la séquence et qu'on ne fait pas le calcul à chaque image, donc pas de perte de performances.
Je ne sais pas si l'application d'un ou plusieurs filtre en temps réel autoriserait la visu à vitesse normale…

Great !

The sad thing is that there actually was a similar feature in the ancestor of Kinovea back in 2005 (screencap from the help files). You could interactively add/remove positions to the composite.

In all those years I never got around to reimplementing it (Massive limitation : it worked only for perfectly fixed camera views. I want it to work even when there is camera motion, but it's much more involved).

Particularly interesting in the first images you posted is that the composition is selective. You see all the ball's positions, but only a few of the racket's ones. This makes for a much clearer image if all you want to see is the ball trajectory.

Hi,
I do not have a specific brand or model recommendation at the moment. Hopefully someone with practical experience can share.

Generally speaking, the camera must support MJPEG or JPEG over HTTP to work as it is currently the only formats implemented.
It's also possible to have WebcamXP receive the stream and serve it back locally in MJPEG for Kinovea consumption.

Hi,
I just tried and yes, you're right :-)

You need to set the .Owner property of the form to be the main Kinovea form for it to work properly.
If your menu handler is inside Kernel.cs, you can simply do this:

form.Owner = MainWindow;

If it's outside, in another module or elsewhere, you can call a similar function through this :

using Kinovea.Services;

Form form = new Form ();
DelegatesPool dp = DelegatesPool.Instance();
if (dp.MakeTopMost != null)
    dp.MakeTopMost(form);
form.Show();

909

(2 replies, posted in Cameras and hardware)

GoPro will not work. I've started to look into it for a future support but it's still a long shot.
I don't know about the liquid 727, but I'd be surprised if it worked.

Regarding the JVC, it should work if it indeed has an MJPEG stream. I can't guarantee that the framerate will be acceptable though, it will depend on the image size they use for the stream and the network bandwidth…

If someone has first hand experience with similar models, input would be much appreciated.

Interesting… The timestamp part might be covered by the existing naming scheme feature. Have you tried that ? From the capture tab in the main preferences you can have the snapshots named automatically with a timestamp. If it needs to have more precision it would probably be simple to integrate.

Then the second part would be to collect the list of files/timestamps in a text log, csv or spreadsheet file.
This could be done entirely in an external program I guess, monitoring the output directory and collecting info on the fly. Or it could be added as an internal feature, but it sort of feel a bit specific…

Another way that might be interesting would be to be able to define an external command to be executed after each snapshot is saved. That would leave the possibilities open and allow for many other uses. The external program would be fed the file name, time stamp and other variables as parameters.

It's more advanced on the user side and would need a bit of programming to get it working but we can probably create scripts for common scenarios as the requests come.

Indeed this thread is initially about instrumenting playback with actions. I moved your message here.

Giving this its own topic.

Alexander wrote:

I am not quite sure if this idea fits in here, but I would very much like to "time stamp" and save images from a streaming video.
Example: I am streaming a finish line of a crosscountry race. When competitors cross the line, I click and save an image with a running clock timestamp. All the timestamps are recorded in a file and can be opened later with Excel/OpenOffice etc. to match with corresponding images.
In this way I have a backup and documentation of the runners.

913

(1 replies, posted in Bug reports)

Indeed the high speed camera setting has no effect on playback speed, it just changes the time base used to compute time values.

The resulting maximum reacheable framerate will depend on the bandwidth of the video (size of images and frames per second) and on the encoding format. The encoding has a great impact on the decoding time. If decoding + display cannot be done in less than the frame interval, frames are skipped. If this repeats constantly, the speed slider is automatically brought down.

In recent versions, the decoder tries to use the display size so that the image can be rendered without interpolation as fast as possible. Try to decrease the size of the image with the corner handles to see if it mitigates the problem.

Welcome smile

Yes, you're correct. You can only save the piece of video that you created, not the process of creation itself.
That would be an interesting one though, but you can also do that with a screen grabbing application like camstudio.

Grouping would be definitely interesting. It'd also be interesting in the context of creating a custom tool out of existing ones. However at the moment it's still not planned for short term.
One question will be: how do you know if the user is dragging the mouse to create a selection or just trying to move the image around.

Regarding pencil tool, merging the pieces of the drawing would be easier to implement as a short term mitigation of the problem.

Regarding temporarily hiding a drawing or a group of drawings, how would you "unhide" it ?