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Hi, I am analysing the influence of cognitive and emotional response on purchase intent.
I have a collection of Likert Scales (1= totally agree, 5=totally disagree) rating the phrases 'This makes me feel happy', 'this makes me feel inspired', 'this makes me feel sad', 'this makes me feel bored' etc. These were answered in response to a Facebook post.
the participants of the study then answered on another Likert scale (also 1= totally agree, 5 totally disagree) rating how the post influenced their purchase intent -rating the phrase 'This makes me want to purchase the product'
I am trying to find a relationships between the emotions and purchase intent, but unsure exactly which analysis on SPSS is more appropriate for this. I attempted a spearman correlation but not sure if it is the right fit and I am not sure how to read the results.
Any suggestions? Thank you!
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Hello Phi,
If it's just pairwise relationships you're interested in, then gamma or spearman rho could suffice. If, on the other hand, you were interested in what ensemble of the "emotion" variables accounts for differences on the reported intent to purchase, then ordinal regression might be suitable.
Good luck with your work.
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Hello All
I'm trying to synchronize imu sensor with the Motion Capture system. Is this possible? If so, how?
thanks for answering
Alireza
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Hi Alireza,
First, what is the type of motion capture system do you have? Most of them actually have their own synchronization box, which serve as trigger in or trigger out for other external device including IMU. However, if your IMU sensor is a standalone sensor without any base to connected, then you can try an option to synchronize it by using some movement that cause spike on IMU signal like jumping.
Hope this helps you
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There is a paper on it [Reference: Grim. O "Die Schwingungen Von Schwimmender Zweidimensionalen", korpern, HSVA, Report 171,1959] but sorry to say that is in 'German language'.
It will be nice of you if you help me to find another article or theoretical source.
(Thanks)
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Dear Mohammed,
maybe it would help to make your question a bit more specific. The plots seems to refer to solution using conformal mapping.
Please mention the reference (in English) from which you took the figure and the short part of the text defining the amplitude ratio.
For some classical references you can take a look at these:
Lewis, F.M., 1929. The inertia of the water surrounding a vibrating ship, in: 37th Meeting of The Society of Naval Architects and Marine Engineers, SNAME.
Ursell, B.F., 1949. On the heaving motion of a circular cylinder. Q. J. Mech. Appl. Math. II, 218–231.
Frank, W., 1967. Oscillation of cylinders in or below the free surface of deep fluids. Naval Ship Research and Development Center, Washington
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We already have transformed accelerometer and gyroscope into position. Our remaining challenge is to calibrate the Y axis correctly for a golf swing (this is the axis that measures perpendicular distance to the golf target. The Y axis 0 point is calculated based on the first 50- 100 miliseconds of activity. If this first movement is in the wrong plane the whole curve will be calculated incorrectly and the first movement will always be counted as zero. Instead we want the correct swing to be zero and any movement outside this correct swing to be either positive on the Y axis or negative. We know the movement of the correct swing plane in the first 100 miliseconds for a golfer, we can measure deltas or delta ratios. I suspect we need to make a fusion metric between accerometer data and gyroscope data and compare the deltas to the right backswing (in first 100 mileseconds). Looking for some scientific insight into this challenge we face please.
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I would like to be able to import footage from 2 or more cameras to analyze the motion of mammals. Lmbs is what mainly interests me.
I know of MOKKA and SkillSpector but SkillSpector has been crashing.
Have you got more suggestions?
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Kinovea
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Looking to automate the process of analyzing video data from CPA experiments in rats. Currently looking into DeepLabCut and Tracktor, but I was wondering if there are any others that allow for analysis of time spent within multiple areas of video. Thanks in advance!
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Hello;
I agree that is the most used in that case.ht the software : EthoVision XT
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What is the best wall color of the lab to use with a IR cameras MoCap system (Qualisys, Vicon, Optitrack...)? We have always used white walls, without any problems. I read that blue color is the best option to use with the IR systems/spectrum. What is your opinion? Any color in particular? (please add pantone-color number)
Thanks
Best,
Jose Heredia-Jimenez Human Behavior & Motion Analysis Lab. HubemaLab. University of Granada in Ceuta.
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Thank you for the answer Dr. Jokstad
Best,
Jose Heredia-Jimenez
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in general, for healthy people, in the 3D motion analysis to define the anatomical coordinate system on segments, one frame in static position is taken by the camera, which will make segment angular changes based on this. Now consider a patient with pelvic abnormalities. The pelvic anatomical frame in this case is defined as zero for a healthy person. It will be different now if a patient completes a corrective exercise. If these exercises affect on the pelvic inclination,our anatomical coordinate system will change in post test. As a result, may the effect of exercise be eliminated in the final results of the comparison of pelvic kinematic pre and post test.
What is the proposed solution?
Is there a resource to fully explain this?
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I follow the question.
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in general, for healthy people, in the 3D motion analysis to define the anatomical coordinate system on segments, one
frame in static position is taken by the camera, which will make segment angular changes based on this. Now consider a patient with pelvic abnormalities. The pelvic anatomical frame in this case is defined as zero for a healthy person. It will be different now if a patient completes a corrective exercise. If these exercises affect on the pelvic inclination,our anatomical coordinate system will change in post test. As a result, may the effect of exercise be eliminated in the final results of the comparison of pelvic kinematic pre and post test.
What is the proposed solution?
Is there a resource to fully explain this?
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I am using Vicon system and trying to answer you according to Vicon.
Your concern is correct. The static frame will be used to zero the offset angle and regard it as the anatomical neutral position. If you do the standard procedure for normal subject, it will be wrong for abnormal offset angles.
If possible, you may do the calculation by "Body Builder", a software for Vicon data modelling.
If not, you may import the trails after intervention into the old data session. You trick the system they are data in the same session. Then, the angle change will be the difference between the old and new static frame.
Hope it helps
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Hi,
I'm working on organ motion modeling specifically for radiation therapy. We do 4D MR acquisition to extract the characteristics of a subject respiratory motion, which is essential for planning of the therapy.
I'm wondering if the intra-subject variability of the respiratory or cardiac motion is also important for some sort of diagnosis. To the best of my knowledge, current dynamic CT or dynamic MR based methods only reconstruct single average motion cycles.
As I'm not a clinician this question might sound quite naive. However, I'm happy for any hints and answers.
Best
Christoph
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Thank's for your answers Fokko and Galya. As I understand you correctly, for your mentioned applications an average cycle or even for looking only onto the heart rate a simple ECG would be enough. I still wonder, if real time resolved 3D images over several respiratory or cardiac cycles are relevant for diagnosis. Or would that open new diagnostic opportunities?
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Hi,
I currently running a study and want to examine one particular aspect, I recorded data using scales of addiction of both cocaine and tobacco users, while also in conjunction with scales of positive affect, negative affect and effortless control. I want to assess the difference between 3 groups of my DV (Cocaine Users, Tobacco Users and Non-drug users) against my 3 independent variables. I have been currently trying to run a ANOVA but due to the way I have coded it, with DrugScores being one variable in SPSS containing the scores of tobacco and cocaine users, followed by the drug scores of non drug users, which are 0 (as they did not do complete either drug scales understandable) , however spss does not appear to let me run this, even after I have dummy coded DrugScores so SPSS knows what scores are what (e.g 1= cocaine users, 2= tobacco users and 3= non drug users) What statistical analysis would you think is the best?
Thank you
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I suppose that your IVs are continuos variables.
Thus you can use determinant analysis: this will predict the appartenance of participants to one of the three groups based on the scores obtained on the 4 IVs.
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The test carried out in ELISA for ANA and CLIA for anti-dsDNA showed negative ANA and positive anti dsDNA result. Is there any condition for such scenario?
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regardless of test method, is there possibility of having this kind of clinical scenario??
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Hi,
I need to estimate the velocity of a series of points. I have the 3D coordinates of these points over time, recorded at 60 frames/s during a a weightlifting movement.
What are the standards in the field of biomechanics for this type of estimation (filter, derivation methods) ?
What are the errors if I simply use a numerical derivation method such as velocity = diff(position)./diff(time).
Best regards.
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From what you have written, I assume that these points you are referring to are 3D coordinates of markers placed on the subject during weightlifting task. Also I am assuming that these points are labelled such that you have a continuous array of 3D coordinates for each marker.
There will be some error in the detected positions due to noise. There are generally two ways how to filter out this noise, either by using Butterworth filter (en.wikipedia.org/wiki/Butterworth_filter) with typically 10 Hz cutoff frequency. You can adjust the cutoff frequency according to the task itself - slower movements = higher cutoff frequency.
The second method to filter the noise is to use Savitzky-Golay method (en.wikipedia.org/wiki/Savitzky–Golay_filter). Here you will have to adjust the order and the frame length. These values are highly dependent on your data and you will just have to test few values to see which give the best results.
Once you filter the data, you can then proceed with obtaining the velocity the usual way, i.e. "velocity = diff(position)./diff(time)" as you wrote.
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I want to detect motor units and specify their recruitment thresholds during 10s ramp contractions. At the moment, during our pilot work, our participants are doing the ramp contractions with visual feedback, since we are using a transparency that we attached to the screen with a triangle. Does anyone know any other alternative for this, such as using a script to insert the triangles in the software itself? Software: Spike 2.
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Hei,
I am so sorry for not answering you sooner but I did not have time yet.... ☹️ It is good to hear that you managed to solve the problem! 😀
Have a nice day!
Annamaria
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Is there any software that can convert an video taken in 360o in to a 3d surface with triangular meshes to enable me to find out its surface area 
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thanks David and Alasdair
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Can somebody explain the process behind obtaining ground truth values from a motion capture device, which can be used for comparison with our proposed system like for eg: Kinect? tell me whether we have to do our work in the presence of both the 3D motion capture (ground truth) and our proposed system(Kinect)
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Hi All, 
Like what Senthil is saying, there is no real gold standard but the closest to that would be motion capture systems such as Vicon or optotrak.  To compare your method you will need to capture the same motion using one gold standard and your technique. In addition you can run these motions multiple times to test repeatability. Then you can get the RMS error or standard deviation as measures of how tour technique measures with these gold standards. Your technique could match the accuracy of gold standards but offer measurement outside structured environments. 
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Is it possible to use Divergence and curl of vectors as a local feature for 3D face recognition?
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Hi
See the given paper, you can get your answer
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Dear all,
  Greetings, I am interested in creating a full body model for Vicon (With Marker set) using the clusters to find the joint center unlike the plug in gait model which has got individual and wand markers.
The idea is to find the reliable joint center for all the major joints thereby reducing the error percentage in the 3D motion analysis (especially in terms of angle interpretations).
While post capturing the same data can be imported into matlab to find the angles and associated graphs for the same.
I will be more than happy to go on with a collaborative study on this. 
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Vasanth,
The marker placement strategy can certainly dictate how you determine the underlying skeletal kinematics.  There are, for example, the point cluster method by Andriacchi et al and minimum marker (less than 3 per body segment) method we developed which would use mathematical optimization to enforce the rigidity of underlying linkage.  Hope this helps.
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Dear all,
Will be happy to know about the performance analysis (the areas to be looked into) in archery and Shooting to improve performance. Have planned for a 2D video analysis (3 Cameras, aerial, Lateral and posterior) and force distribution Center of Pressure (COP) between the foot using AMTI Force plates. However, need more literature support on this and any possibilities of incorporating 3D Mocap technology and any other additional available technology to this?
Available normative data and any further guidance will be of great support. 
Thanks in Advance.
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Hope some of this can help. Especially work of Mr.Ertan.
You can also look for unpublished doctoral thesis "The analysis of shooting dynamics in archery" by Tinazci C.  and  "Total Archery" book (Samick Sports) by Lee K. and Bondt R. 
I hope You will find some of this information helpful.
Kind regards,
Jan Homolak
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Studying elite baseball players and I understand the problems with the plug in gait model for issues including the location and reference of the glenohumeral joint centre, the definition of the anatomical coordinate system of the humerus, and the shoulder joint angle decomposition. Further, there appears no standardized model for throwing in research in this area, despite the ISB standards for upper limb modelling. Any help would be greatly appreciated! 
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Hello Peter,
I would say that it depends on the level of accuracy you want to get and the general purpose of computing these variables (for discriminating different phases of a particular movement, f.ex.). If these are simple kinematic quantities (angular motion of joint angles or limb accelerations...) ,  I think you can either use the upper limb models you mentioned. The variations in the limb/joints during movement execution would follow a pattern close to real, I assume. Otherwise, I would recommend to create your own model (for throwing) by yourself in Nexus.
I would be curious to see the distortions between such a model and the ISB standards.
Halim
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For my dissertation I am lucky enough to research 3D MOT(multiple object tracking) software to identify progression in MOT. 3D MOT has a great clinical background with improving peripheral awareness, pedestrian avoidance for elders, recover from injury and it also boasts the ability to improve decision making. As the software I will be using is up and coming in the professional sporting environment I would like to test the relationship of MOT and decision making skills however the question arises as to is it possible to test decision making skills in a sport environment? And if so how? Is it academically backed?
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Sorry - I inluded the wrong link in my previous post. The link should be:
The link I mistakenly put might also be useful to you however, since it deals with the related problem of tracking objects whose trajectories are not straight (i.e. that involve turns, etc.).
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I am working on 3D Explicit Dynamic model of in bore analysis of gun barrel in ABAQUS. My loading condition is pressure which varies with time.Now I have define magnitude as 1 and in amplitude I have defined the pressure time value which is varying with time .But I am not getting the desired displacement of bullet.
Thanks in advance
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In Abaqus  solver, load (pressure) can be applied as a function of time and space. For defining space variation, you need to define it as a function. However there are various ways in which one can define pressure/time relation. you can add any amplitude (Pressure vs time ) data as a CAE input. amplitude can be added in number of ways like tabular, periodic etc.
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Please elaborate or refer a source:
How is procedural Generated Animation (PGA) using procedural programming techniques, as used in Games industry, different form Physics or Dynamics based Animation techniques for biped or quadruped locomotion?
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A procedural animation is any animation controlled by programmer goal, not real-life one. Examples: procedural generation of plants, particle systems, movement along motion graph, etc. Often such applications are designed just to provide nice look and widely use random elements. But still in the simulation Physics and Dynamics can be used.
If planning of the next group of steps in your case of locomotion depends on game events and interaction with the scene objects, this is not “procedural-based” animation. If the actor or animals walk through the scene in random direction this is a kind of procedure generated animation. In any case algorithm of locomotion simulation still is based on Dynamics or Inverse Kinematics.
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I need to configure Osprey Digital RealTime System of Motion Analysis to my Laptop. If you have experience on initial configuration settings please be kind enough to share them. 
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I am not sure whether you want to know about software or hardware configuration settings. There is a Quick Start Guide that comes along with the Users Reference manual that describes the software settings and how to aim and focus the Osprey cameras. Appendix A in the Reference Manual describes how to connect the cameras to a computer.
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Basically, I am new to 3D motion analysis and trying to figure out how to do it. This said, I lack basic knowledge regarding the issue. I only have experience with 2D gait analysis.
Say I already have video recording from multiple angles (and this is all I have), including video recordings for calibration purposes, and I now want to analyze a quadrupedal animal's motion, mainly focusing on joint movements of the limbs, and gait.
How would I proceed with this? What skills should I learn, what software should I use? File formats?
I am aware of this program:
But we do not have the budget to acquire it. So I am looking for workarounds and open-source/free programs.
I don't mind the learning curve or the requirements, I just need to figure out a way to do this.
Many thanks for your help. I am looking forward to your suggestions and comments.
P.S. I have tried SkillSpector, but I cannot import the videos. I tried several codecs/containers, but it just won't recognize them.
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hello Nikolaos
I used Kinovea (freeware) to retrieve the target coordinates in 2D on both camera.
Then I concatenate two 2D data with a DLT (direct linear transformation) to obtain 3D with matlab, labview or openCV (freeware) script
Abdel- Aziz Y. I, Karara H.M., 1971. Direct Linear Transformation from Comparator Coordinates into ObjectSpace Coordinates.ASP Symposium on Close- Range Photogrammtery, Falls Church, VA, pp.1-18.
enjoy
Patrick
Institut of Mouvement SciencesMarseille, France
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I am about to undertake some residual analysis to select a cut of frequency to smooth some 3D coordinate data I have collected. 
The question I have is what trials I should use for the residual analysis. Should I select a number of random trials for each subject, mean for each marker and use that data? So the filter will be consistent between subjects and potentially different for each marker. Or run each subjects trials separately, so the filter can potentially be different between subjects and each marker? 
Any help will be greatly appreciated, I've been unable to find any literature for guidance.
Thanks
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Mr. Richardson
I utilize an example for better comprehension.
In gait analysis, because of different movement linear and angular velocity in different segment for optimum cut off frequency, according to the winter, (1) researchers should apply residual analysis for each of the markers attached to the body. The only problem of such process is time consuming, so there is another way for finding optimum cut off frequency is classifying the markers into segments which means, (2) utilizing one marker of each segment as reference for finding the optimum cut off frequency. For example in the plugin gait marker placement we have three markers on the ankle segment which we can use one of the markers as apply residual analysis for obtaining the appropriate cut off and apply to the other marker of the the ankle segment as well (not the other segments). (3) Another approach is utilizing one cut off frequency for all of the markers. In this process we should apply the residual analysis for at least two of markers, one with lesser velocity and the other with maximum velocity of the trial and then average them to find the most suitable cut off frequency.
I should mention that from approach 1 to approach 3, the diminution of accuracy and precision will be seen, and should analyzed, which the differences will not statistically significant. In the gait example winter find the optimum cut off as 6 Hz for all of the markers. So the quota of accuracy and precision you need is the key to find the way that detects the optimum cut off frequency.
Hope that it helps you.
Yours truly
Alighanbari
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Give me an example to compute the velocity of motion in video.
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You can use vision.OpticalFlow object.
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I have come across lots of non-linear stability measures used in fall prediction of the elderly, however these all require a large volume of gait cycles. Has anybody come across gait stability measures which can be used on say 5-10 gait cycles? I'm also interested in stabiltiy measures which utilise kinetic information. Thanks.
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Hi Paul, 
Indeed, as Sina points out, a lot of measures are mentioned in my thesis. However, most of that is also published, and the best article to get you started would be this one :"Assessing the stability of human locomotion: a review of current measures.
Bruijn SM, Meijer OG, Beek PJ, van Dieën JH.
J R Soc Interface. 2013 Mar 20;10(83):20120999.". It's also online here on researchgate. In it, you will read that it's also possible to use short data series for these stability analysis. For this, I would highly recommend the work of Kim van Schooten. 
Best,
Sjoerd
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Is it through an inverse dynamics approach? How reliable/accurate are the joint moments? I want to determine if the plug-in-gait moments can be used as control parameters for a muscle force algorithm.
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Hi jacobus
sorry for the delay of my answer.
I never compare plugin gait and opensim model. I should do it.
You have to know that kinematic calculations of these models are different.
opensim considers a-priori definite joint axes and uses an inverse kinematic optimization (Lu, T., & O’connor, J. (1999). Bone position estimation from skin marker co-ordinates using global optimisation with joint constraints. Journal of Biomechanics, 32, 129–134.)
Plugin gait only considers ball joint at all articulation and extracts cardanic angles.
No model can be a golden approach !
regards
Fabien
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Does anyone know any special program to analyze 3D staples of cells (detected with an 510 ... Zeiss CLSM)? Imaris is to expensive. Has anyone a freeware suggestion. It would be great if this program produces files where you can zoom into the cell.
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You can try BioImageXD (http://www.bioimagexd.net/).
Hope it work...............
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We are working with Vicon Nexus system, studying sprint and jump kinematics. The model we use is plug-in-gait full body and we are interested to obtain the subject's center of mass, but sometimes one or more markers are lost due to high speed of these actions. Is there any way to calculate CoM if any marker is missing?
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I think its possible.
First you should find and fix the "gaps" for the specific marker with a fourth order polynomium. This works well for gaps until 6 to 7 frames. If your frame rate is to high, you probably have more missing frames, but if the suggested path looks well, you may accept it.
You should try to set lower frame rates (100 Hz e.g.) and try this option.
Good luck with your work.
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I would like to calculate the three dimentional angles for some joints like shoulder and elbow. i know what it's mean but I don't know how to calculate them practically. I can calculate them with a IR base motion analysis system(Motion Analysis Corporation- Santa Rosa) but my current motion analysis system is "SIMI". It is a video base system. Unfortunately i don't know how to use that for this purpose, and it has a really bad manual, because u can't understand any thing in that.
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Dear David,
A way to understand 3D angles is to think of the idea of the orientation of one object to another - take a plane in the air. its orientation relative to the airport tower is described as the planes yaw - or horizontal rotation about a vertical axis of the plane , its Pitch , or the rotation about the lateral axis through the wings, and its roll - its rotation about the long axis of the body of the plane . So basically its the relationship of the axis system in the body relative to another axis system - now in Biomechanics we just replace the plane with a limb segment and then translate the terminology into clinical terminology. These angles are calculated from a 3x3 matrix called the orientation matrix, rotation matrix, and other names. The angles can be derived from this matrix are called Euler angles or Cardan angles . There are a couple other methods using Quarternions, and Helical axes but these have a bit more clinical translation challenge.
Anyway it is possible to calculate these angles easily with matlab for example.
The best way to learn and understand about 3d angles is to have a simple model with markers creating and XYZ reference frame - and move the model around in space in known orientation then calculate and observe the 3d Angles. There are lots of tricky things with 3d angles ( ie Gimbal lock) . I recommend a book called intro to robotics by Craig - he does a really nice job explaining the whole orientation issue and the matrices. Hope this helps ,
Kevin