Topic: measure area of certain color

Hi there,

I've been trying out Kinovea for a while now and like it a lot!! Thanks.

My use is mostly with bike fitting, getting my self aero. So my feature request is... would it be possible to build a tool (or is there a tool) which would measure/count the area of a certain color (green screen) so one can determine if the frontal area is getting bigger or smaller with a change of postion on the bike?

Would be great is this was a "live" tool so one could see on the spot if a postion change is positive or negative in regards to the frontal area.

I hope this makes sense.

Can imagine this would be a usefull tool in others sports as well


Guido

Re: measure area of certain color

Hi,

There is currently no tool for measuring an area in Kinovea.
I was also thinking about this recently while updating the tools for the next version.

I was thinking about a drawing tool where you "paint" an area and then you can right click that shape and make it show the measured cm² or whatever based on calibration. This way you could draw exactly the silhouette of the person.

I think what you are mentioning is to discard all pixels that are similar enough to a given hue and count the rest. That might be simpler to use if the room can be set up this way. I'm not sure how accurate that will be though, there will always be missed pixels in the background and false positive in the foreground.

The advantage of the green screen method is that it could be dynamic for free, whereas the painted area would only work for a single frame and you would have to edit it after each change of posture. The drawback of the green screen method though is that it doesn't readily fit in the tool framework and the player pipeline so it will complicate the architecture.

So far there is no clear path. Are you or anyone aware of other software that provide that type of area measurement feature (and that are not using a depth camera to do so)? Can the green screen approach be mocked up in Photoshop or something to see how accurate it would be and what is influencing the results precision?

Re: measure area of certain color

Hi Joan


The "paint" version would be nice indeed but has the downside of being labour intensive if you want to compare multiple positions.

The green screen solution has a margin or error, this mainly depends om the lighting of the subject (and clothing choise) and the background, but in general I this this margin will be small enough. Green or blue screen is higly tested in film and profided you set it up correctly works very well


http://bioraceraero.com/en/home#en/frontal-area

is a software tool that uses a webcam (and is way to expensive for me ;-)  )

There where some apps for Apple as far as I know but couldn't find a working app for  Android.

And in PS one could use the histogram to count the pixels or percentage of a color(range)