Faces, Bodies and Rectangles

I have finally got Viola-Jones implemented in OpenCV in Python evern if the faces it detects on the PETS 2009 data sets are not very accurate. As I am sure grass does not have a face. I will work on fine tuning it and maybe even combining it with HoG(histogram of orientated gradients) person detection.

Thats another thing I have implemented, using some of OpenCVs example code but tweaked to be a little more modular. HoG person detector can now pick up people in images with a reasonable degree of accuracy. Both this, Viola-Jones and any future implementations will be checked against the ground truth for the set of images. This will give me an idea of how accurate the implementations are when values are changed or my own combinations/implementations are used.

HoG detection green boxes, Viola-Jones in blue boxes

I have also written tests for my files that I have made such as img_handler.py, viola_jones.py and hogDetector.py using pytest. This allows me to test all the methods to make sure they do what they are meant to and will not break when passing certain data. This makes them good for regression tests or if I ever need to change something in them. There are some parts which I have not tested as they require user input. I am currently looking it to simulating this to be able to test them.

Showing my tests completing successfully

The only ground truth file I have come across for PETS 2009 is one from this site for scenario S2.L1. This comes in a .xml file so I will be looking at parsing this to get the relevant data for comparison. I am also looking at other data sets to test more. As well as this I am looking into creating my own small test data set of around 6 people, a plan of what will be acted is currently being drafted up.

I have encountered a few problems over the past few days one of which being OpenCV on Ubuntu 14.04... again. I think due to a recent install of some software I damaged the OpenCV install that I had previously done. After following the steps from this website again it was up and running. As well as this the HoG detector was not picking up al people but after a few tweaks with some settings to do with it I am now picking up most of the samples with a few false positives. As well as making it more accurate in certain aspects it has also increased the time taken to process images. Viola-Jones needs some tweaking with its settings as it is detecting faces where there are definitely not faces, such as the grass.

I have also altered the file I was using to manually step through the images to do it automatically and put the results from both Viola-Jones and HoG detector. These are then saved and will be turned it to a video which will be linked on this site when up and running. It will have a voice over explaining what is going on and what each rectangle is .


 My next tasks if I manage to get that all done as well as a few improvements to files is to work on optical flow tracking. This will require me to compare positions of people in a previous image to current image and map their movement over time. This will be done in a different colour that will hopefully get darker the faster they appear to be moving. When I have that working I will post a video on YouTube and some images on here.

So that's it for this week, got a lot to crack on with hopefully won't be too bad and hopefully OpenCV won't mess up again.