Progress Report - 12/20/15

• Progress:
• I downloaded the jimp module, an alternative/complement to opencv whose library seems to be documented and explained more thoroughly.
• The file I required in the node test program is weird, called index.js or something. I couldn’t find a file named jimp.js, which would usually signal the file with all the others required. However, it seems to work; I’ve tried a few methods w/o error-"not a function".
• I created a rudimentary tracking function given an single image (the image type [.png] matches the images which the drone should feed to the computer):
• 1) I use opencv to threshold the image for red
• 2) Then I feed that output to jimp
• 3) I use jimp to analyze the pixels and their neighbors (for now, horizontally) at a set distance
• 4) I use jimp to find average X and Y of retained pixels
• 5) I now have the marker’s location in the image, along with its horizontal and vertical limits (I draw a point at that location).
• 6) I can now approximate the radius of the marker by finding the average difference between each limit and the center.

• Problems: (Crossed out, because I resolved the problem)
• I tried testing jimp, but the png image I read which was the output of an opencv method came up undefined in pixel color when I tried to read pixel(0,0).
• I think it’s because png images can be formatted in different ways, with different numbers of bytes per pixel.
• I also tried jpg, but that also came up as undefined. I haven’t researched jpg formatting, but perhaps there’s a similar problem.
• Perhaps there’s a way to convert an image to rgba before reading it with jimp.
• Perhaps there’s a way to output an image with a specific data format.
• Solution:
• the color RGBA values returned are not stored in a matrix; they are stored as properties of the color object. 
• So color[0] = undefined, but color.r = the amount of red in the image 
• :)

• Plans:
• Test
• stream = new opencv.ImageStream()
• stream.on(‘data’, function(matrix) {
• //image conversion
• //image analysis (retrieve marker location)
• }
• ardrone.createPngStream().pipe(stream)
• //Perhaps learn how to output the imageStream to a window display OR send the imageStream to a web browser to display. I know for a fact that the latter is possible; I’ve seen it done.
• Improve Tracking Function
• Incorporate vertical neighbors
• Check neighboring pixels at intermediate distances to improve erosion function’s accuracy, so I can lower the distance
• Incorporate ardrone.createPngStream() to input video
• Display video output in browser?
• This isn't really necessary, but would be nice
• Drone
• Test command loops in the drone by putting land() and takeoff() in a repeating loop
• Use location and marker radius in command sequence for drone
• put location.x in center of image by setting yaw value
• move until marker.radius is greater than a certain value
• I assume marker.radius graphed per distance from marker would be a “1/x” kind of function...
• Fix leaning in drone flight
• HOW???
• Try another drone?
• Perhaps leaning is OK, once the drone starts following a marker path to correct is drifting
• Pseudocode for Final Program
• Store command string specified by user
• Take off
• variable: Image = empty
• variable: radius = 0
• variable: Y = constant //used to spin un a direction until marker is found
• for (command in command string) {
• while (no marker is detected in the following image) {
• Get image from drone
• Detect marker location, using the tracking function
• Send image to user //Maybe; not necessary
• Yaw += Y
• }
• while (radius < R) {
• if (location.y is too far from equator) change height
• if (location.x is too far from meridian) change yaw
• if (neither of the above) move forward
• while no marker is detected in the following image {
• Get image from drone
• Detect marker location
• Send image to client
• Yaw += Y
• }
• }
• Stop
• if (command == end) {
• Land
• }
• else if (command == left/right) {
• Change yaw left/right
• }