Preprocess Error

[連振宇]

Dear community,
I follow the tutorial 1 of youtube, and I change the pictures (Img000000) into my own (the cal folder as shown below). In the pyPTV program, when I press "High pass filter", there is no blue cross. Then, when I press "Image coord", the program will pop up with the following error. What is the reason for this?  

[Alex Liberzon]

please upload somewhere or attach here some images, better a complete working folder with the parameters and some images. we could then recommend a different set of parameters.

if it's not possible, try to change the grey scale threshold, size of the blobs (x,y,total pixels) until you get some crosses.

[連振宇]

My image is in the attached compressed file
thank you

alex.l...@gmail.com 在 2022年12月13日 星期二凌晨3:23:29 [UTC+8] 的信中寫道：

[Alex Liberzon]

These images are binary, 0, and 1. The code that analyzes them is written in C, and it expects 8-bit greyscale TIFF. So first, the highpass cannot do a thing on these images and second - you could theoretically set your grey scale threshold to 1 and try to detect particles, but it won't be very effective, I think.

Plus don't forget to change the parameters of the image size, etc.

there is one more limitation that I see - is the way the files are numbered. I'd suggest to use 10000, 10001, etc. then you can set Sequence with img/Stack#.tif and in the values to give 10000 and 100010. When we set 0000.tif - it fails to understand how many digits are required.

I can recommend to use plugin and write in Python a small code that identifies those blobs and stores their pixel position in the _target files. Then use in the Main parameters [Use existing targets] option and here you go.

Since this is just a 2D case, maybe using trackpy can be a faster solution. OpenPTV is actually faster, but it's less robust in terms of the blob detection

[Alex Liberzon]

I mentioned trackpy, but I think also MyPTV would be simpler in this case, though I'm not sure it works in 2D

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[しょうことう]

Hello Alex,

This Zitao, sorry to bother again.

As you mentioned MyPTV, I am wondering what's the difference bettwen MyPTV and OpenPTV?

I saw the introduction on Github of MyPTV says:
The main difference is that the code is written in Python, thus making it accessible to a wider scientific community. Furthermore, MyPTV uses several new adaptations of the traditional algorithms that have been introduced in recent years, e.g. [2-6], and several novel algorithms that we are using were developed here.

It looks like the main difference is OpenPTV uses C, while MyPTV uses python, and MyPTV includes several new algorithms. Is this understanding correct?

The ultimate goal of our research is to apply PTV in indoor ventilation study and also wind tunnel.

Limited by the cemeras, we are currently testing the 2-D PTV/PSV.

Do you have any suggestions on the software? Is it better to use MyPTV or OpenPTV?

[Alex Liberzon]

Hi Zitao

i cannot recommend one or another. You would have to try it yourself and see which one is more suitable to your case. Each one ( there are other options as well that we didn't mention) has its pros and cons. Depending on the main use case - some pros might be more beneficial. 

in 2D case both software are "overkill" - we focus on 3D and most of the time the calculation is about how to find and track 3D particles in turbulence. 

regards

Aelx

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Subject: Re: Preprocess Error

 

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[しょうことう]

Hi Alex

Thank you for your quick reply. I will try both OpenPTV and MyPTV first.

We definitely would like to do 3D particle track, but we don't have experience on the post-processing of PTV,

I am still exploring the OpenPTV/MyPTV.

If the 2D works, we will buy more cameras and do 3D track.

Regards 

Zitao

[Alex Liberzon]

Please, write here about your experience with both - this audience is really interested in the opinion of our new users. That's the way to improve open-source software.

I'm sure that the author of MyPTV would like to know about which things are better done in his software.