Raspberry Pi - Image processing for UAV navigation

Thanks Eduardo,

I have been away for the weekend but will be trying out your code tomorrow, it looks like that may fix my problem, or maybe I really want it to.

James, think that link is broken now, did you mean Texas in QLD or USA?

Anyway, I'll be on tomorrow to reveal if the problem is fixed and if so I'll post the max frames per second I can get my program running at.

Cheers,

Dan

I hope you don't live in Texas. Although, it is a great Q.

http://www.popsci.com/technology/article/2013-02/privacy-and-drones

I had that same problem. I'm not completely sure but I think it's like a buffer in which images have to be retrieved in order, as they are captured. What I did was manage every interaction with the user with the OpenCV WaitKey function and keep reading and showing the image.

This is a test program for the laser range finder. I modified it from somewhere but I've lost the link. It takes a couple of images, differences them, and makes some other processing to find the laser pointer position. You might need to make some changes for the specific version of OpenCV you are using. (Sorry about formatting, I didn't find how to quote code, if you tell me I will edit this)

#! /usr/bin/env python

import sys

# import the necessary things for OpenCV
from opencv import cv
from opencv import highgui


def TakePic(capture):
    highgui.cvNamedWindow ('camera', highgui.CV_WINDOW_AUTOSIZE)
    while 1:
        img = highgui.cvQueryFrame(capture)
        
        size = cv.cvGetSize(img)
        centerx = size.width/2
        centery = size.height/2
        crosslen = 4

     cv.cvLine(img,cv.cvPoint(0,centery),cv.cvPoint(size.width,centery),cv.cvScalar(255,255,0))
     cv.cvLine(img,cv.cvPoint(centerx,0),cv.cvPoint(centerx,size.height),cv.cvScalar(255,255,0))
     cv.cvLine(img,cv.cvPoint(centerx-crosslen,centery),cv.cvPoint(centerx+crosslen,centery),cv.cvScalar(255,255,0),2)
     cv.cvLine(img,cv.cvPoint(centerx,centery-crosslen),cv.cvPoint(centerx,centery+crosslen),cv.cvScalar(255,255,0),2)

        highgui.cvShowImage('camera',img)
        k = highgui.cvWaitKey(5)
        if k >= 0:
            return img



if __name__ == '__main__':

    # a small welcome
    print "OpenCV Python capture video"

    # first, create the necessary window
    highgui.cvNamedWindow ('1', highgui.CV_WINDOW_AUTOSIZE)
    highgui.cvNamedWindow ('2', highgui.CV_WINDOW_AUTOSIZE)
    highgui.cvNamedWindow ('3', highgui.CV_WINDOW_AUTOSIZE)

    # move the new window to a better place
    #highgui.cvMoveWindow ('Camera', 10, 10)

    device = 0

    capture = highgui.cvCreateCameraCapture (device)

    # check that capture device is OK
    if not capture:
        print "Error opening capture device"
        sys.exit (1)

    img1 = TakePic(capture)
    simg1 = cv.cvCloneImage(img1)
    cv.cvSmooth(img1,simg1)
    imgg1 = cv.cvCreateImage(cv.cvGetSize(simg1), cv.IPL_DEPTH_8U, 1)
    cv.cvCvtColor(simg1,imgg1, cv.CV_RGB2GRAY)
    highgui.cvShowImage ('1', simg1)
    
    img2 = TakePic(capture)
    simg2 = cv.cvCloneImage(img2)
    cv.cvSmooth(img2,simg2)
    imgg2 = cv.cvCreateImage(cv.cvGetSize(img2), cv.IPL_DEPTH_8U, 1)
    cv.cvCvtColor(simg2,imgg2, cv.CV_RGB2GRAY)
    highgui.cvShowImage ('2', simg2)

    img3 = cv.cvCloneImage(img1)
    imgg3 = cv.cvCreateImage(cv.cvGetSize(img2), cv.IPL_DEPTH_8U,1)
    bitimage = cv.cvCreateImage(cv.cvGetSize(img2), cv.IPL_DEPTH_8U, 1)

    #cv.cvAbsDiff(simg2,simg1,img3)
    #cv.cvCvtColor(img3,imgg3, cv.CV_RGB2GRAY)
    print cv.cvAbsDiff(imgg2,imgg1,imgg3)
    simg3 = cv.cvCloneImage(imgg3)
    cv.cvSmooth(imgg3,simg3)
    cv.cvThreshold(simg3,bitimage,16,255,cv.CV_THRESH_BINARY)
    eimg3 = cv.cvCloneImage(bitimage)
    cv.cvErode(bitimage,eimg3)

    #highgui.cvShowImage ('3', bitimage)
    highgui.cvShowImage ('3', simg3)
    highgui.cvNamedWindow ('th', highgui.CV_WINDOW_AUTOSIZE)
    highgui.cvShowImage ('th', bitimage)
    highgui.cvNamedWindow ('eroded', highgui.CV_WINDOW_AUTOSIZE)
    highgui.cvShowImage ('eroded', eimg3)

    moments = cv.CvMoments()
    cv.cvMoments(eimg3,moments,0)
    moment10 = cv.cvGetSpatialMoment(moments,1,0)
    moment01 = cv.cvGetSpatialMoment(moments,0,1)
    area = cv.cvGetCentralMoment(moments,0,0)
    posX = int(moment10/area)
    posY = int(moment01/area)
    print "laser at "+str(posX)+","+str(posY)

    cv.cvCircle(simg2,cv.cvPoint(posX,posY),15,cv.cvScalar(0,255,0),2)
    cv.cvCircle(simg2,cv.cvPoint(posX,posY),2,cv.cvScalar(0,255,0),2)
    highgui.cvShowImage ('2', simg2)

    cv.cvSave("diff.png",bitimage)
 
    print "Bye"
    # handle events
    k = highgui.cvWaitKey (100000)
    #cv.cvReleaseCapture(capture)

Hi all,

I have got openCV working for python and C, just using python for now. But I have ran into problems and need help since I've tried everywhere and everything I can think of.

-Using python with openCV but can use C instead

-Running Raspberry Pi, 512Mb model B

-Using a logitech QuickCam Communicate MP/S5500 Webcam

Now, my ultimate goal is to capture an image, wait some time, capture another image, merge (add) the images together, save the output.

The issue is the second image captured is just like the first, dispite the program correctly waiting, the camera does not wait to capture the next image. I have tried in both python and C and had the same issue so I believe I must be missing some key element.

Here is the Code:

# PudFish
# cvTest.py
# 11 Feb 13

from cv import *

SIZE=(HEIGHT,WIDTH)=(640,480) # Image capture size
CAMERA_INDEX=-1 # -1 means any camera attached
WAIT_TIME=10 # In seconds

cam=CaptureFromCAM(CAMERA_INDEX) # Initializes capturing a video from a camera
SetCaptureProperty(cam,CV_CAP_PROP_FRAME_WIDTH,WIDTH) # Set the capture image width
SetCaptureProperty(cam,CV_CAP_PROP_FRAME_HEIGHT,HEIGHT) # Set the capture image height

img1=QueryFrame(cam) # Capture an image and store as img
print "img1 captured"
SaveImage("img1.png",img1) # Save the img to file
print "img1 saved"

# Delay, indexed for debugging
for i in range(0,WAIT_TIME):
print "i: %d" %i # Print the current index
WaitKey(1000)

img2=QueryFrame(cam) # Capture an image and store as img
print "img2 captured"
SaveImage("img2.png",img2) # Save the img to file
print "img2 saved"

# Print the data types and ID's for debugging
print "img1 Type: %s" %type(img1) # Print the data type of the img variable
print "img1 ID: %d" %id(img1) # Print the unique ID of the img1 object
print "img2 Type: %s" %type(img2) # Print the data type of the img variable
print "img2 ID: %d" %id(img2) # Print the unique ID of the img2 object

And the Output:

VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
VIDIOC_QUERYMENU: Invaild argument
img1 captured
img1 saved
i: 0
i: 1
i: 2
i: 3
i: 4
i: 5
i: 6
i: 7
i: 8
i: 9
img2 captured
img2 saved
img1 Type: <type 'cv2.cv.iplimage'>
img1 ID: 1147448688
img2 Type: <type 'cv2.cv.iplimage'>
img2 ID: 1147448712

So, I had the webcam facing the monitor for debugging:

-img1 shows the last line as "VIDIOC_QUERYMENU: Invaild argument"

-img2 shows the last line as "i: 2"

Now the odd thing which occurs, I comment out the capturing of img1, and then img2 is captured at the correct time, i.e. the last line in the picture is i: 9

Let me know if you need any more info or to clear things up, thanks in advance for any help.

Dan.

Thanks Eduardo,

That's a big help, and yeah I can't wait till the CSI camera, just have to put up with the webcam for now.

Thanks,

Dan.