Shape recognition

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Socoder -> Blitz -> Shape recognition
Sat, 14 Apr 2007, 13:48
Blitz3Dman	For school I and my other classmates were assigned to come up with a project (like a science fair except this year it didn't have to be science) and do it. I programmed this program that takes a photo of a green shape on a red background and, using linear regression, finds the slopes of two of the lines and some fancy equations to find the angle with that information finds out if it is my square or my equilateral triangle. (sorry never got around to uploading the images and they're on a floppy that I turned in to my teacher, not on my machine :/ sorry) I thoroughly enjoyed the headaches this project gave me not really but I learned a lot and I couldn't have done it without some help from my grandpa to find the equations and to think up some algoritms to iron out the last of the bugs. (My grandpa, by the way, used to program in BASIC, you know, on those computers that you had to write the code on notecards and feed them into a machine with no screen? yea, those computers. LOL) ;references: ; ;This program reads an image with a green shape on a red background. It will recognize an equilateral ;triangle and a square/rectangle. It does so by construcing the best fit line using linear regression ;from the collection of points on one side of the shape. It first checks the bottom line and then the ;left side line. Using the slopes of the two lines the program calculates the angle and determines ;which of the shapes it is accordingly. Const gw=400,gh=300 ;file Global file=WriteFile("log.txt") Type pt Field x,y End Type Const steppit=1 ;line variables Global n% ;SIGMA values Global Sxy# ;SIGMA (xy) Global Sx# ;SIGMA x Global Sy# ;SIGMA y Global S_x2# ;SIGMA (x^2) Global Sx2# ;(SIGMA x)^2 ;m values Dim m#(2) m(1)=0.000 ;angle Global PHI#=0.000 ;setup the window Graphics gw,gh,0,2 SetBuffer BackBuffer() ;pick image randomly SeedRnd MilliSecs() todo=Rand(0,0) Select todo Case 0:image=LoadImage("tri.bmp") Case 1:image=LoadImage("square.bmp") End Select SetBuffer ImageBuffer(image) ;find the bottom line For x=1 To gw Step steppit For y=1 To gh Step steppit GetColor(x,400-y) If ColorGreen()>ColorRed() Then p.pt=New pt WriteLine(file,"Edge found at x "+x+", y "+y) p\x=x p\y=400-y Exit EndIf lastr=ColorRed() lastg=ColorGreen() lastb=ColorBlue() Next Next WriteLine(file,"points to calculate m1 retrieved") Gosub sigmas ;calculate variables to use in calculating m ;calculate m 1 m(1)=((nSxy)-(SxSy))/((nS_x2)-(Sx2)) WriteLine(file,"m1 is equal to "+m(1)) ;delete all the points For p.pt=Each pt Delete p Next ;find the left side line For y=1 To gh Step steppit For x=1 To gw Step steppit GetColor(x,y) If ColorGreen()>ColorRed() Then p.pt=New pt WriteLine(file,"Edge found at x "+x+", y "+y) p\x=x p\y=y Exit EndIf lastr=ColorRed() lastg=ColorGreen() lastb=ColorBlue() Next Next WriteLine(file,"points to calculate m2 retrieved") Gosub sigmas ;calculate variables to use in calculating m ;calculate m 2 m(2)=((nSxy)-(SxSy))/((nS_x2)-(Sx2)) WriteLine(file,"m2 is equal to "+m(2)) ;find the angle WriteLine(file,"Calculating PHI") PHI=ATan((m(1)-m(2))/(1+(m(1)m(2)))) WriteLine(file,"PHI is equal to "+PHI) ;main loop SetBuffer BackBuffer() Color 255,255,255 Repeat Cls DrawImage image,0,0 Text 10,10,"slope of bottom line is "+m(1) Text 10,25,"slope of left line is "+m(2) Text 10,40,"the measure of the angle is "+PHI+" degrees" If PHI>80 And PHI<100 Then Text 10,240,"the read angle is approximately 90 degrees." Text 10,255,"therefore the figure is a square/rectangle." EndIf If PHI>50 And PHI<70 Then Text 10,240,"the read angle is approximately 60 degrees." Text 10,255,"therefore the figure is an equilateral triangle." EndIf Flip Until KeyDown(1) CloseFile file End .Sigmas ;calculate SIGMA (xy), SIGMA x, SIGMA y, SIGMA (x^2), (SIGMA x)^2, and n n=0 Sxy=0 Sx=0 Sy=0 S_x2=0 Sx2=0 a=0 aa=0 For p.pt=Each pt a=a+1 Next For p.pt=Each pt aa=aa+1 If aa>5 And aa<a-5 Then Color 255,255,255 Plot p\x,p\y n=n+1 Sxy=Sxy+(p\xp\y) Sx=Sx+p\x Sy=Sy+p\y S_x2=S_x2+(p\x^2) Sx2=Sx2+p\x EndIf Next ;finish calculating (SIGMA x)^2 Sx2=Sx2^2 WriteLine(file,"number of points used in calculation is equal to "+n) WriteLine(file,"SIGMA (xy) is equal to "+Sxy) WriteLine(file,"SIGMA x is equal to "+Sx) WriteLine(file,"SIGMA y is equal to "+Sy) WriteLine(file,"SIGMA (x^2) is equal to "+S_x2) WriteLine(file,"(SIGMA x)^2 is equal to "+Sx2) Return ;references: ;https://tpub.com/math2/5.htm ;https://phoenix.phys.clemson.edu/tutorials/excel/regression.html --v -=-=- There are 10 kinds of people in this world - ( Insert 16 remarks about to what extent people know hex here )