理論上は
位置を時間で微分すると速度
速度を時間で微分すると加速度
ってなりますよね。
映像分析では、映像から任意の点の位置座標を算出することができますので、映像から加速度を求められないか試してみました。
映像の座標の単位
腕を真下から肩の高さくらいまで振るという単純な運動を行いました。
任意の点を自動追尾（トラッキング）を行います。
今回は同時に加速度計も使用したので、加速度計を自動追尾させました。
その点の位置情報を座標として表示。
さぁ、ここまではいいのですが、映像座標の単位って「ピクセル」ですよね…。
そこで、映像中に映っている加速度計の幅4.2cmを基準としcmで表示しました。
さらに原点は出発（開始）地点に設定。
得られた位置座標が
Excelで微分って…
なので、差分をとる方法で行いました。
映像は1/60秒での時間軸なので、誤差は大きくなりますが今回は試しなのでこのまま続行。
加速度計から得られた加速度データのX成分と、映像から得られた加速度のX成分を比較したのが下図です。
※赤線が加速度計、濃青が映像からのデータで30区間移動平均
加速度計は重力によるセンサ誤差がある？
今回はX成分のみで比較しました。
映像からのデータはただ差分をとっただけなので、バラつきが大きいことがわかります。
しかし、理論上から推測される加速度に近似するのは映像からのデータではないでしょうか。
映像からのデータはほぼ±1Gを振幅しています。
これに対し、加速度計のX成分は-1Gを極小とした振幅。
加速度のX成分の平均は計算するまでもなくマイナスとなるので、位置はどんどんマイナス方向に下がることになります。
ここで、重力の1Gを考慮しても波形は映像と異なります。
もっと単純な運動で違いができる原因を検討
今回は映像からのデータから加速度の値を求め、それがどれほど加速度計の値と相違するのかがぼんやりとわかりました。
次回はもっと単純な横だけの運動などで、さらに検討してみたいと思います。
ただ、加速度計も映像からも波形は似たものが出ているので、単位や重力の考慮など誤差がわかればいいのでは、と考えます。
映像は2次元平面ですが、加速度はX,Y,Zの3次元ですので、使い分けが必要ですね！
Thanks for this post, I am a big big fan of this site would like to continue updated.
That is the proper blog for anybody who wants to seek out out about this topic. You realize a lot its nearly hard to argue with you (not that I really would want…HaHa). You positively put a brand new spin on a topic thats been written about for years. Nice stuff, just great!
Viagra Und Cialis Forum cheap cialis Vmax Viagra
Thanks for ones marvelous posting! I really enjoyed reading it,
you are a great author.I will always bookmark your blog and will
eventually come back later on. I want to encourage one to continue your great work, have a
nice evening!
This is the perfect web site for everyone who really wants to understand this topic.
You realize so much its almost hard to argue with you (not that
I personally will need to…HaHa). You definitely put a new spin on a topic which has been discussed for a long time.
Excellent stuff, just wonderful!
Hi, all is going fine here and ofcourse every one is sharing data, that’s truly excellent, keep up writing.
It’s not my first time to pay a quick visit this web page, i am visiting this
web site dailly and take good data from here every day.
Levitra Pastiglie Acquisto Sildenafil 100mg levitra with dapoxetine reviews Sumatriptan Amoxil Kill Strep
I’m really enjoying the theme/design of your blog.
Do you ever run into any browser compatibility problems?
A handful of my blog audience have complained about my site not operating
correctly in Explorer but looks great in Firefox. Do you have any suggestions to help fix this
issue?
Your style is so unique compared to other folks I have read stuff from.
Many thanks for posting when you’ve got the opportunity, Guess I will just bookmark this site.
Hello! This is my first visit to your blog! We are a team of volunteers and starting a new initiative in a community in the same niche.
Your blog provided us useful information to work on. You have done a marvellous job!
What i do not understood is if truth be told how you
are no longer really much more smartly-appreciated than you might
be now. You are very intelligent. You understand therefore significantly when it comes to this subject, produced
me for my part believe it from so many varied
angles. Its like women and men don’t seem to be fascinated except it is
something to accomplish with Girl gaga! Your personal stuffs outstanding.
All the time take care of it up!
What a information of un-ambiguity and preserveness of valuable
knowledge concerning unpredicted feelings.
Hello, just wanted to mention, I loved this article.
It was practical. Keep on posting!
What’s up to every one, the contents existing at this web site are actually amazing for people
experience, well, keep up the nice work fellows.
Hi, always i used to check web site posts here early in the dawn, since
i love to gain knowledge of more and more.
Simply desire to say your article is as astonishing.
The clarity in your post is simply cool and i can assume you are an expert
on this subject. Fine with your permission let me to grab your RSS feed to keep
updated with forthcoming post. Thanks a million and please continue the enjoyable work.
This is the perfect web site for anybody who really wants to
find out about this topic. You realize so much its almost hard to argue with you (not that I actually
will need to…HaHa). You definitely put a new spin on a topic that has been discussed for
many years. Great stuff, just wonderful!
Thanks for a marvelous posting! I seriously enjoyed reading it, you could be a great author.I
will make certain to bookmark your blog and will often come
back at some point. I want to encourage yourself to continue your great writing, have a nice
morning!
Keep this going please, great job!
Hello just wanted to give you a quick heads up.
The words in your post seem to be running off the screen in Firefox.
I’m not sure if this is a format issue or something to do with browser compatibility but I thought I’d post to let you know.
The layout look great though! Hope you get the issue fixed soon. Kudos