implement own Haar-Cascade

Please post the steps of what exactly you did.

i download and insert path of xml file in script
when i want run script in raspbian return this error

Can you run it from the terminal so we can see the error ?

here I converted the file for you. (12.9 KB)

Is there any tutorial to learn this topic like this??

No the script should work out of the box though, anyway we’re going to add a built-in cascade converter to the IDE it’s just a matter of time.

It looks like you have html in your script… i.e. you didn’t download it right…

thanks for replying

How to write the xml file to the script or in the other words how to Introduce xml file to script?

Hi, you pass the xml file after the script name.

I put the xml name in the script or in the terminal ?
if i must put in script
It is possible to place the modified file?

Hi download the script like so:


Then run it like this:

python2.7 cascade_file.xml

Thank you so much

hai,i got a problem here,when i try to convert the xml file using converter as here :
i got an error. So here i attach the xml file.Seem i stuck to convert to cascade file.After that,does the cascade embedded directly to camera or i need to transfer the cascade into internal memory to load on another script.
myhaar.xml (1.75 KB)

The converter doesn’t work on Windows, try the attached cascade.

You need to copy the cascade to flash or sd card, see examples and replies to this post. (222 Bytes)

it all done,thanks to you.But the detection still low rate,does i need to add more positive image during making a cascade?.here i attach the video and also coding

import sensor, time, image

lens_mm = 2.8 # Standard Lens.
average_spool_height_mm = 360.0 #
image_height_pixels = 240.0 # QVGA
sensor_h_mm = 2.952 # For OV7725 sensor - see datasheet.
offest_mm = 100.0 # Offset fix…

focal length - How do I calculate the distance of an object in a photo? - Photography Stack Exchange

def rect_size_to_distance®: # r == (x, y, w, h) → r[3] == h
return ((lens_mm * average_spool_height_mm * image_height_pixels) / (r[3] * sensor_h_mm)) - offest_mm

Reset sensor


Sensor settings


HQVGA and GRAYSCALE are the best for face tracking.


Load Haar Cascade

By default this will use all stages, lower satges is faster but less accurate.

spool_cascade = image.HaarCascade(“myhaar.cascade”, stages=1)

FPS clock

clock = time.clock()

while (True):

Capture snapshot

img = sensor.snapshot()

Find objects.

Note: Lower scale factor scales-down the image more and detects smaller objects.

Higher threshold results in a higher detection rate, with more false positives.

objects = img.find_features(spool_cascade, threshold=0.75, scale_factor=1.25)

Draw objects

for i in range(len(objects)):
img.draw_string(objects[0] - 16, objects[1] - 16, “Distance %d mm” % rect_size_to_distance(objects))

img.draw_cross(img.width()//2, img.height()//2, size = min(img.width()//5, img.height()//5))

Print FPS.

Note: Actual FPS is higher, streaming the FB makes it slower.

print(“FPS %f” % clock.fps())_

I’m not sure, maybe try a lower scaling factor (1.15).

it’s done.thanks…Now i’m designing alignment algorithm for AGV.Openmv camera as input,then arduino as controller also encoder for each mecanum wheels as feedback for positioning agv.Btw can i make that openmv determine the spool position either left or right side plus with distance from camera(already done) to tell AGV position(Camera) against spool(target) ?

@aqeelyaacob Please post a new topic for that with as much details as possible.